Palaeontological Society of Japan

ISSN 0031 -0204

Transactions and Proceedings

of the Palaeontological Society of Japan

New Series No. 147

Palaeontological Society of Japan October 30.1987 Co-Editors Hisayoshi IGO and Tsunemasa SAITO

Officers for 1987-1988

President: Tatsuaki KIMURA Honorary President: Teiichi KOBA YASH I Councillors: Kiyotaka CHINZEI, Takashi HAMADA, Yoshikazu HASEGAWA, Itam HAYAMI, Hisayoshi lGO, Junji lTOIGAWA, Tadao KAMEl, Tatsuaki KIMURA, Tamio KOTAKA, Kei MORI, Ikuwo OBATA, Tsunemasa SAITO, Yokichi TAKAYANAGI, Kazushige TANABE, Toshimasa TANAI Members of Standing Committee: Kiyotaka CHINZEI (Membership), Takashi HAMADA (For eign Affairs), ltaru HAYAMI (Finance), Hisayoshi lGO (Co-Editor of Transactions), lkuwo OBATA (General Affairs), Sumio SAKAGAMI (Co-Editor of Special Paper), Kazushige TANABE (Planning), Yokichi TAKAYANAGI (Editor of "Fossils"), Juichi YANAGIDA (Co-Editor of Special Paper) Secretaries: Katsumi ABE (Planning), Takeshi ISHIBASHI (Special Paper), Kunihiro ISHIZAKI ("Fossils"), Tomoki KASE (General Affairs and Membership), Hiroshi NODA (Editor of Transactions), Terufumi OHNO (Membership), Tatsuo OJ! (Planning), Kazuhiko UEMURA (General Affairs), Toshiyuki YAMAGUCHI (Finance) Auditor: Noriyuki lKEYA

The fossil on the cover is Vicarya yokoyamai Takeyama, an Early Middle Miocene gastropod from the Kurosedani Formation at Kakehata, Yatsuo-cho, Nei-gun, Toyama Prefecture, central Japan (Collected by T. Kotaka and K. Ogasawara, lGPS No. 99075, photo by S. Ohtomo and Y. Kikuchi, xO.9).

All communication relating to this journal should be addressed to the PALAEONTOLOGICAL SOCIETY OF JAPAN % Business Center for Academic Societies, Yayoi 2-4-16, Bunkyo-ku, Tokyo 113, Japan Trans. Proc. Palaeont. Soc. Japan, N. S., No. 147, pp. 91-108,7 Figs., October 30,1987

832. CRETACEOUS EOMIODON AND COSTOCYRENA (BIVALVIA) FROM SOUTHWEST JAPAN

MASA YUKI TASHIRO

Department of Geology, Faculty of Science, Kochi University, Kochi 780

Abstract. In this paper 4 species of Eomiodon and 8 species and 2 subspecies of Costo cyrena (including Costa cyrena oh n ish ii, sp. nov., Costocyrena hojiensis, sp. nov. and Costo cyrena otsukai obsoleta, subsp. nov.) belonging to the Family Neomiodontidae are described from the Cretaceous at various localities in southwest Japan. Geographic distribution of Eomiodon and Costocyrena species seems to change through the Cretaceous time in southwest Japan. In the Lower Cretaceous, Eomiodon species restricted ly occur from the southern side of Kurosegawa Tectonic Belt, while all Costocyrella species are known from the northern side of that belt, Northern Chichibu Belt. In the Upper Cretaceous, the geographic distribution of the two genera becomes overlap, and they occur together even at the same localities especially in central Kyushu. This may not mean habitat change of these bivalves, but seems to support the hypothesis of the Early Cretaceous movement of a large lateral fault in the Chichibu Belt.

Introduction da of Kochi Pref. for their supply of material. The studied specimens (KSG) are kept in the Many species of Eomiodon and Costocyrena Faculty of Science, Kochi University. belonging to the Family Neomiodontidae widely thrived during the Cretaceous times in Japan. Systematic descritpion They occur abundantly from the various strati graphic horizones characterized by the so-called Family Neomiodontidae Casey, 1955 brackish water facies, ranging from Hauterivian Subfamily Eomiodontinae Hayami, 1965 to Cenomanian, at many localities in Southwest Japan. Genus Eomiodoll Cox, 1935 Eomiodon and Costocyrena species described Eomiodon sakawanus (Kobayashi et Suzuki) in this paper seem to be important for the corre Figures 1-7-12 lation of the Cretaceous strata in Japan. Chang ing of the geographic distribution of Eomiodol1 1939. Astarte sakawana Kobayashi et Suzuki, Japan. and Co:.,tocyrena species through the Cretaceous Jour. Ceol. Ceogr., vol. 13, nos. 3-4, p. 219, pI. times also involve interesting problems both on 13, fig. 11 (non pI. l3, figs. 12 and 13). 1973. Eomiodon sakawanus (Kobayashi et Suzuki); palaeoecology and tectonic developments of Ohta, Bull. Fukuoka Univ. Educ., vol. 22, no. 3, eastern Asia. p. 250, pI. 1, figs. 1-11. I wish to express my sincere thanks to Miss 1975. Eomiodon sakawanus (Kobayashi et Suzuki); Takako Ohnishi of Kagawa Pref., Mr. Hideyuki Hayami, Univ. Mus., Ulliv. Tokyo, Bull., 10, p. Yanagisawa of Fukui Pref. and Mr. Seiji Matsu- 138. 1976. Eomiodon sakawanus (Kobayashi et Suzuki); *Received September 16, 1986; revised manuscript Ohta, Atlas of Japanese fossils, vol. 44, Meso accepted July 6, 1987; read June 15, 1985 at Osaka zoic bivalves (3), figs. 7-9. City University.

91 92 Masayuki TASHIRO

Materials:-KSG 3803 and KSG3804,external figs. 1-7. 1981. Eomiodon matsumotoi Ohta; Ohta, Bull. Fuku moulds of right valves, from Uchiyama of Aioi, oka Univ. Educ., vol. 31, no. 3, p.103, pI. 7, figs. Tokushima Prefecture. KSG 3805 and KSG 1-8. 3806, external moulds of right and left valves, from Yonenomoto of Ittku, Kochi City. Materials:-KSG 3807-KSG 3810, external Measurements:-(in mm.) moulds of left valves; KSG 3811, external mould Specimens Length Height Thickness of right valve; all from Ohta of Tanoura, Ashi KSG 3803, r. ext. mol. 13.0 11.0 2.5 kita-gun in Kumamoto Prefecture. KSG 3812 - KSG 3804, r. ext. mol. 10.0 9.0 1.5 KSG 3813, external moulds of left valves, from KSG 3805, r. ext. mol. 14.1 11.5 2.5 Uchiyama of Aioi, Naka-gun in Tokushima KSG 3806, I. ext. mol. 18.0 15.0 2.0 Prefecture. Remarks:-The holotype was occurred from Measurements:-(in mm.) the Kaisekiyama Formation of Kamo, Sakawa in Specimens Length Height Thickness Kochi Prefecture. Two species, treated in this KSG 3807,1. ext. mol. 29.5 23.0 4.0 study (Figures 5-1, II and 12), preserved in the KSG 3809, I. ext. mol. 10.5 88.0 2.0 Fossil Museum of Sakawa (not registered), were KSG 3811, r. ext. mol. 22.0 16.0 3.0 also collected from the type locality. Remarks: - This species is characterized by the This species is characterized by more broadly very fine concentric striae which are developed spaced concentric ribs on the disk and less in on the interspaces of the concentric ribs on the flated valve than other Japanese Eomiodon disk. Although this species resembles Eomiodon species. About 5 concentric ribs are countable sakawanus (Kobayashi et Suzuki) in its roundly on the adult stage. They are narrower than their subtrigonal outline of the valve and distinct con interspaces and roof-shaped on the top. centric ribs on the disk, it difers from E. sakawa Occurrence and geological age: - Fine-grained nus in its more inflated valve, numerous and sandstone of the Nakaizu Formation at Uchi more or less irregularly spaced concentric ribs, yama of Aioi, Naka-gun in Tokushima Prefec and fine concentric striae on their in terspaces. ture; Aptian. Very fine-grained sandstone of the Occurrence and geological age: -Gray siltstone Funadani Formation at Ittku of Kochi City, of the Kawaguchi Formation at Ohta of Tanoura, Kochi Prefecture; Aptian. Sandy mudstone of Ashikita-gun, Kumamoto Prefecture; Hauterivian. the Kaisekiyama Formation at Kaisekiyama of Fine-grained sandstone of the Shobu Formation Sakawa, Kochi Prefecture. This species is also at Uchiyama of Aioi, Naka-gun in Tokushima known from the upper part of the Yamabu Prefecture; Hauterivian. This species had been Formation at Yamabu, Minami-Amabe-gun in reported from the lower member of Doganaro Oita Prefecture; Aptian(?). Formation of the Shimanto Belt in Kochi Prefec ture (Katto and Tashiro, 1979) and from the Eomiodon matsumotoi Ohta lower part of Yamabu Formation of the Chichi Figures 1-1-6 bu Belt in Ohita Prefecture (Tashiro, 1985a), both in the Hauterivian in age. This is also known 1973. Eomiodon matsumotoi Ohta, Bull. Fukuoka from the Uminoura Formation in central Kyushu Univ. Educ., vol. 22, no. 3, p. 245, pI. 2, figs. l (Ohta and Monji, 1976). The geological age of B. 1975. Eomiodon matsumotoi Ohta; Hayami, Univ. the Uminoura Formation is probably the earliest Mus., Univ. Tokyo, Bull., 10, p. 139. Cretaceous. 1976. Eomiodon l1latsul1lotoi Ohta; Ohta, Atlas of Japanese fossils, vol. 44, Mesozoic bivalves (3), Eomiodon matsubasensis Tamura figs. 10-15. 1979. Eomiodon matsul1lotoi Ohta; Katto and Tashiro, Figures 1-13-25 Res. Rep., Kochi Univ., vol. 27, Nat. Sci., pI. 2, 832. Cretaceous Eomiodon and Costocyrena 93

1977. Eomiodon matsubasensis Tamura, Mem. Fac. gun in Kumamoto Prefecture. This is also known Educ. Kumamoto Univ., no. 26, Nat. Sci., p. 107, from the Fukigoshi Formation of the Sotoizumi pI. 6, figs. 9-19. Group at Nagase of Odochi, Monobe-mura of 1982. Eomiodon matsubasensis Tamura; Tashiro and Matsuda, Trans. Proc. Palaeont. Soc. Japan, N.S., Kami-gun in Kochi Prefecture (Lower Ceno no. 127, p. 410, pI. 65, figs. 14-15. manian) (Tashiro and Matsuda, 1982). 1985. Eomiodon matsubasensis Tamura; Matsuda, Fos sils, no. 39, pI. 2, figs. 9-10. Eomiodon? kumamotoensis Tamura

Materials:-KSG 3814-KSG 3815, external 1959. Eomiodon kumamotoensis Tamura, Trans. Proc. moulds of left and right valves, from Higashi Palaeont. Soc. Japan, N.S., no. 33, p. 115, pI. 12, machi (Shishijima island) in Kagoshima Prefec figs. 17-18. ture. KSG 3816-KSG 3818, external moulds of 1960. Eomiodon kumamotoensis Tamura; Tamura, left and right valves, from Karakizaki (Goshono Mem. Fac. Educ. Kumamoto Univ., vol. 8, Nat. Sci., p. 240. ura island) in Kumamoto Prefecture. KSG 3819 1975. Astarte? kumamotoensis (Tamura); Hayami, - KSG 3810, external moulds of left and right Univ. Mus., Univ. Tokyo, Bull., 10, p. 128. valves, from Chikaraishi, Kami-mashiki-gun in 1986. Eomiodon kumamotoensis Tamura; Tashiro and Kur-.amoto Prefecture, KSG 3821-KSG 3830, Katto, Res. Rep., Kochi Univ., vol. 34, Nat. Sci., external moulds of left and right valves, from pI. I, figs. 15-17. Furuyashiki (Goshonoura island) in Kumamoto Material:-KSG 3931, conjoined valves, from Prefecture. Tainokawa of Obama, Susaki City in Kochi Measurements:- (in mm.) Prefecture. Specimens Length Height Thickness Remarks:-The typical specimen of this KSG 3816, r. ext. mol. 15.0 14.0 4.0 species was described from the Upper Jurassic KSG 3818, r. ext. mol. 9.0 8.0 2.0 Sakamoto Formation of the Torinosu Group at KSG 3814, I. ext. mol. 13.0 11.5 3.0 Sakamoto in Kumamoto Prefecture, by Tamura KSG 3823,1. ext. mol. 11.0 8.0 2.0 (1959). KSG 3819, I. ext. mol. 4.0 3.5 1.0 Occurrence and geological age:-Dark greenish KSG 3825, 1. ext. mol. 6.5 6.5 2.0 gray mudstone of the basal part of Doganaro Remarks:-Numerous specimens are undoubt Formation of the Shimanto Belt at about 350 m edly conspecific with Eomiodon matsubasensis west of Tainokawa of Obama, Susaki City in Tamura (1977) are collected from the Mifune Kochi Prefecture; Uppermost Jurassic or lowest Group in central Kyushu. Cretaceous. Occurrence and geological age:-Dark gray to greenish gray mudstone of the lower member of Genus Costocyrena Hayami, 1965 Mifune Group at Chikaraishi, Mashiki-machi of Costocyrena radiatostriata (Yabe et Nagao) Shimo-mashiki-gun in Kumamoto Prefecture; Figures 2-13 - 22 Middle Cenomanian. Very fine-grained sandstone of the S-I1 Formation of Goshonoura Group at 1926. Cyrena radiatostriate Yabe et Nago, in Yabe, Tateishi, Higashimachi (Shishijima island) of Nagao and Shimizu, Sci Rep., Tohoku Imp. Izumi-gun in Kagoshima Prefecture; Lower Ceno Univ., Ser. 2, vol. 9, no. 2, p. 51, pI. 12, figs. 29-35. manian. Greenish gray mudstone of the Upper 1965. Costocyrena radiatostriata (Yabe et Nagao); (III) Formation of Goshonoura Group at Kara Hayami, Mem. Fac. Sci., Kyushu Univ., Ser. D, kizaki, Goshonoura-machi (Goshonoura island) Geol., vol. 17, no. 2, p. 73, pI. 19, figs. 1-7. of Amakusa-gun in Kumamoto Prefecture; Lower 1975. Costocyrena radiatostriata (Yabc et Nagao); Cenomanian. This species is common in the Hayami, Univ. Mus., Univ. Tokyo, Bull., 10, p. 140. lower member of the Mifune Group at Magano, 1976. Costocyrena radiatostriata (Yabe et Nagao); Subayashi and Katashida areas of Shimo-mashiki- 94 Masay uki TASHIRO

5 3 2 4

30 13

29 27 26

32 37 36 832. Cretaceous Eomiodon and Costocyrena 95

Ohta, Atlas of Japanese fossils, vol. 44, no. 3, species to Costocyrena. The present species figs. 22-26. undoubtedly belongs to Costocyrena radiato 1977. Costocyrena radiatostriata (Yabe et Nagao); striata (Yabe et Nagao) by the diagnostic char Matsukawa, Jour. Ceol. Soc. Japan, vol. 83, no. 2, pI. 1, fig. 8. acters of which were well defined by Hayamai 1979. Costocyrena radiatostriata (Yabe et Nagao); (1965). Matsukawa, Ibid., vol. 85, no. 1, pI. 1, figs. 3,4 Occurrence and geological age:-Dark-gray and 9. mudstone of the lower member of Yunoki For 1979. Costocyrena sp. B aff. C. radiatostriata (Yabe et mation of the Monobegawa Group at Todorono Nagao); Matsukawa, Ibid., vol. 85, no. 1, pI. 1, figs. 1-2. taki of Hibihara (Monobe area), Kami-gun in 1980. Costocyrena radiatostriata (Yabe et Nagao); Kochi Prefecture; Upper Barremian. Tashiro et al., in Taira and Tashiro eds. Ceology and paleontology of the Shimanto Belt, pI. 10, Costocyrena matsumotoi Hayami fig. 18. Figures 5-1-13 Materials:-KSG 3831-KSG 3835, right valves: KSG 3836-KSG 3840, left valves; all 1965. Costocyrena matsumotoi Hayami, Mem. Fac. from Todoronotaki of Hibihara, Monobe-mura, Sci., Kyushu Univ., Ser. D, Ceol., vol. 17, no. 2, Kami-gun in Kochi Prefecture. p. 133, pI. 18, figs. 2-12. 1975. Costocyrena matsumotoi Hayami; Hayami, Univ. Measurements:-(in mm.) Mus., Univ. Tokyo, Bull., 10, p. 140, pI. 7, figs. Specimens Length Height Thickness 10-11. KSG 3836, r. v. 9.5 7.0 2.5 1976. Costocyrena matsumotoi Hayami; Ohta, Atlas KSG 3837, r. v. 9.5 7.5 1.0 of Japanese fossils, vol. 44, Mesozoic bivalves, no. 3, Cr. 26. KSG 3838, r. v. 14.5 13.5 3.6 1981. Costocyrena matsumotoi Hayami; Ohta, Bull. KSG 3834, 1. v. 10.5 9.0 4.5 Fukuoka Univ. Educ., vol. 31, no. 3, p. 103, pI. KSG 3839, r. v. 16.5 12.5 2.0 8, figs. 8-12.

Remarks:-This species was described original Materials:-KSG 3841-KSG 3843, external ly from the Sebayashi Formation of Sanchu in moulds of right valves; KSG 3844-KSG 3853, central Japan. Hayami (1965) referred this external moulds of left valves; all from Jhoguzan

~ Figures 1-1-6. Eomiodon matsumotoi Ohta, xl 1, KSG 3807; 2, KSG 3811; 3, KSG 3808;4, KSG 3809; 5, KSG 3810; Loc. Ohta of Tanoura, Ashikita-gun, Kumamoto Pref., 6, KSG 3812; Loc. Mamidani of Nakaizu, Kami-katsu-gun, Tokushima Pref. 7-12. Eomiodon sakawanus (Kobayashi et Suzuki) 7, KSG 3803; 8, KSG 3804; x1.5, Loc. Uchiyama of Aioi, Naka-gun, Tokushima Pref., 9, KSG 3805; 10, KSG 3806; xl, Loc. about 200 m south of Yonenomoto, Kochi City, Kochi Pref., 11 and 12, x1.5, Loc. Kaisekiyama of Kamo, Sakawa, Takaoka-gun, Kochi Pref. 13-25. Eomiodon matsubasensis Tamura, x2 13, KSG 3816; 14, KSG 3817; 15, KSG 3818; Loc. Karakizaki, Goshonoura-jima, Amakusa-gun, Kumamoto Pref., 16, KSG 3814, Loe. Higashimachi, Shishijima, Izumi-gun, Kagoshima Pref., 17, KSG 3821; 18, KSG 3822; 19, KSG 3823; 21, KSG 3824; 22, KSG 3825; 23, KSG 3826; 24, KSG 3829; 25, KSG 3830; Loc. Furuyashiki of Hongo, Goshonoura-jima, Amakusa-gun, Kumamoto Pref., 20, KSG 3819, Loc. Chikaraishi of Miyanomoto, Kamimashiki-gun, Kumamoto Pref. 26-30. Costocyrena otsukai otsukai (Yabe et Nagao), x2 26, KSG 3910, Loc. Tatsukawa of Katsuura, Kamikatsu-gun, Tokushima Pref., 27, KSG 3907, Loc. Yoneno moto of Ittku, Kochi City, Kochi Pref., 28, KSG 3912; 30, KSG 3905; Loc. Kaganoi of Kuma, Kochi City, Kochi Pref., 29, KSG 3913, Loc. Kami-Koshigoe, Minami-Amabe-gun, Ohita Pref. 31-37. Costocyrena otsukai obsoleta, subsp. nov., x2 31, KSG 3896, holotype; 32, KSG 3899, paratype; 33, KSG 3900, paratype; 34, KSG 3901, paratype; 35, KSG 3897, paratype; 36, KSG 3902, paratype; 37, KSG 3898, paratype; Loc. Idaira of Inasa, Shizuoka Pref. All the specimens are gum cast of the external moulds, except for 11 and 12. 96 Masayuki TASHIRO of Miyaji (type locality of this species by Haya moulds of right valves; KSG 3857-KSG 3859, mi, 1965), Yatsushiro City in Kumamoto Prefec external moulds of left valves; both from Doiban ture. of Yunoki (Monobe area), Kami-gun, Kochi Measurements:-(in mm.) Prefecture. KSG 3860-KSG 3862, external Specimens Length Height Thickness moulds of left and right valves, from Imaizumi of KSG 3841, r. ext. mol. 20.0 16.5 4.5 Yatsushiro City in Kumamoto Prefecture. KSG 3842, r. ext. mol. 11.0 8.5 2.3 Measurements:-(in mm.) KSG 3843, r. ext. mol. 10.0 9.0 2.0 Specimens Length Height Thickness KSG 3845, I. ext. mol. 14.5 11.5 3.5 KSG 3857, 1. ext. mol. 5.0 4.5 1.0 KSG 3850, I. ext. mol. 21.0 18.0 4.5 KSG 3858, I. ext. mol. 6.0 5.5 1.0 KSG 3852, I. ext. mol. 15.0 11.0 4.0 KSG 3854, r. ext. mol. 5.5 5.0 1.0 Remarks:-Many external and internal moulds KSG 3859, I. ext. mol. 6.5 5.5 1.4 of this species are at hand. This specis resemblts KSG 3860, r. ext. mol. 6.0 4.8 1.0 Costocyrena radiatostriata (Yabe et Nagao), in its KSG 3862, r. ext. mol. 5.0+ 5.0 1.2 subtrigonal outline, but it differs clearly from the latter by its less numerous and distinct concen Remarks:-The specimens from the Monobe tric ribs on the disk, and less numerous and area in Kochi Prefecture, are somewhat larger stronger radial striae on the disk. than the specimens from the Yatsushiro area in Occurrence and geological age:-Dark gray Kumamoto Prefecture. Other features between mudstone of the Yatsushiro Formation at the specimens from the two areas, are entirely Jhoguzan of Miyaji, Yatsushiro City in Kuma identical in each others. This species is discrimi moto Prefecture; upper part of the Lower Albian nated from Costocyrena radiatostriata (Yabe et by Matsumoto etal. (1981). Nagao), in its very smaller valve, and more dis tinct concentric ribs on the disk. Costocyrena minor Ohta Occurrence and geological age:-Dark greenish gray mudstone of the basal part of Hibihara Figures 2-29-33 Formation at Yunoki of Odochi, Kami-gun in 1981. Costocyrena minor Ohta, Bull Fukuoka Univ. Kochi Prefecture (Monobe area); Aptian. Dark Educ., vol. 31, no. 3, p. 103, pI. 8, figs. 19-36. gray mudstone of the Miyaji Formation at Ima izumi Yatsushiro City in Kumamoto Prefecture Materials:-KSG 3854-KSG 3856, external (Yatsushiro area); Aptian(?). This species is also

~ Figures 2-1-12. Costocyrena ohnishii, sp. nov., x2 1, KSG 3884, paratype; 2, KSG 3881, paratype; 3. KSG 3882, paratype; 4, KSG 3885, paratype; 5, KSG 3880, holotype; 6, KSG 3883, paratype; Loc. Tatsukawa of Katsuura, Kamikatsu-gun, Tokushima Pref., 7, KSG 3887, paratype; 8, KSG 3892, paratype; 9, KSG 3893, paratype; 10, KSG 3891, paratype; 11, KSG 3886, para type; 12, KSG 3888, paratype; Loc. idaira of inasa, Shizuoka Pref. 13-22. Costocyrena radiatostriata (Yabe et Nagao), x2 13, KSG 3831; 14, KSG 3836; 15, KSG 3837; 16, KSG 3838; 17, KSG 3839; 18, KSG 3840; 19, KSG 3832; 20, KSG 3833; 21, KSG 3834; 22, KSG 3835; Loc. Todoronotaki of Yunoki, Odochi area, Kami-gun, Kochi Pref. 23-28. Costocyrena mifunensis Tamura, x2 23, KSG 3864; 24, KSG 3865; 26, KSG 3866; 27, KSG 3867; 28, KSG 3863; Loc. Karakizaki of Goshonoura jim a, Amakusa-gun, Kumamoto Pref., 25, KSG 3868; Loc. Higashimachi of Shishijima, Izumi-gun, Kagoshima Pref. 29-33. Costocyrena minor Ohta, x2 29, KSG 3857; 30, KSG 3858; 31, KSG 3854; 32, KSG 3859; 33, KSG 3855; Loc. Doiban of Yunoki, Odochi area, Kami-gun, Kochi Pref. All the specimens are gum casts of the external moulds. 832. Cretaceous Eomiodon and Costocyrena 97

1 5

11 2 6

8 12

13 15 16

21 20

23 18 22 27 28

24 33

29 30 31 32 98 Masayuki TASHIRO known from the basal part of the Hinagu Forma (Shishijima island), Izumi-gun in Kagoshima tion (Aptian) at Koda of Yatsushiro City in Prefecture; Lower Cenomanian. The type speci Kumamoto Prefecture. men (KE2669) by Tamura (1977), was recorded from the Lower Formation of Mifune Group Costocyrena mifunensis Tamura (Middle Cenomanian), in central Kyushu. Figures 2-23-28 Costocyrena hojiensis, sp. nov. 1977. Costocyrena mifunensis Tamura, Mem. Fac. Figures 3, 5-28-37 Educ. Kumamoto Uiz iv. , no. 26, Nat. Sci., p. 107, pI. 12, figs. 12-20. Materials:-Holotype, KSG 3869, left external 1985. Costocyrena mifunensis Tamura; Matsuda, Fos mould; paratypes, KSG 3870-KSG 3871, right sils, no. 39, pI. 2, fig. 8. external moulds; paratypes, KSG 3872-KSG Materials:-KSG 3863-KSG 3867, external 3875, left external moulds; KSG 3877-KSG moulds of right and left valves, from Furuyashiki 3879, internal moulds of left and right valves; of Hongo, Goshonoura island in Kumamoto all from Tatsukawa of Katsuura-machi, Toku Prefecture. KSG 3868, right external mould, shima Prefecture. from Higashi-machi, Shishijima island in Kago Diagnosis:-Shell trigonally ovate; umbo shima Prefecture. strongly prosogyrous, located at about one Measurements:-(in mm.) fourth or less from front of valve; surface with Specimens Length Height Thickness numerous concentric ribs; posterior carina weak. KSG 3863, r. ext. mol. 15.0 10.0 2.0 Description:-Shell moderate in size, trigonal KSG 3864, r. ext. mol. 11.5 7.0 3.0 ly ovate or roundly subtrigonal in outline, weak KSG 3865, I. ext. mol. 19.0 13.0 4.0 ly inflated, longer than high; umbo small, a little KSG 3866, r. ext. mol. 16.0 8.0 3.0 prominent, strongly prosogyrate for the genus, KSG 3867, I. ext. mol. 11.0 8.0 2.0 located at about one fourth or one fifth from KSG 3868, r. ext. mol. 16.0 9.5 2.0 front of valve; anterior dorsal margin short, weakly concave; anterior margin nearly straight, the specimens from the Remarks:-Although forming a blunt angle about 110° with broadly Goshonoura Group, treated in this paper, are de arched ventral margin; posterior margin weakly fonned, they are undoubtedly identified with convex; posterior dorsal margin long, slightly Costocyrena mifunensis Tamura, from the convex; posterior carina weak; escutcheon nar Mifune Group in central Kyushu, by its strongly row but elongated; lunule very narrow, distinctly elevated concentric ribs on the disk and broad ened area behind the posterior carina. This species is easily discriminated from other species of Costocyrena, e.g., C. radiatostriata (Yabe et Nagao), C. minor Ohta or C. otsukai (Yabe et Nagao), in its very strong concentric ribs, less numerous but strong radial striae, and broadened posterior slope (area) behind the posterior carina. Occurrence and geological age:-Dark gray mudstone of the upper formation (III) of Gosho noura Group at Furuyashiki of Hongo, Goshono ura-machi (Goshonoura island), Amakusa-gun in Kumamoto Prefecture; Lower Cenomanian. Fine grained sandstone of the SolI (Katasoba) Forma Figure 3. Sketch of the holotype, Costocyrena tion of the Goshonoura Group at Higashi-machi hojiensis, sp. nov. 832. Cretaceous Eomiodon and Costocyrena 99 depressed from the disk; surface ornamented with crowded concentric ribs; ribs roof-shaped, narrower than their interspaces, number about 20 on adult specimens; hinge of lucinoid, cardi nal 2 and 3b large, oblique; cardinal 3a small, subvertical; inner margin smooth. Measurements:-(in mm.) Specimens Length Height Thickness KSG 3872, I. ext. mol. 12.0 10.0 2.0 KSG 3873, I. ext. mol. 15.0 11.0 2.0 KSG 3869, I. ext. mol. 13.0 9.0 3.0 KSG 3874, I. ext. mol. 13.0 9.5 2.0 KSG 3870, r. ext. mol. 16.0 13.0 3.5 KSG 3875, I. ext. mol. 16.5 12.0 3.5 KSG 3871, r. ext. mol. 17.5 13.0 5.0 Figure 4. Sketch of the hoiotype, Costocyrena ohnishii, sp. nov. Observation:-On some specimens of this species very fine and numerous radial striae to two fifths from front of valve; surface orna appear subinternally on the interspaces of the mented by strongly prominent and crenulated concentric ribs on the disk. The posterior carina concentric ribs which are very widely spaced; is very weak except for umbonal region. posterior carina distinctly angulated. Comparison: - The immature forms of this Description:-Shell moderate in size, trigonal species are closely similar to the mature forms of ly ovate or elliptically sub trigonal in outline, Costocyrena minor Ohta, in having its sub trigo more or less inflated, slightly longer than high; nal outline of the valve and remarkable concen umbo prominent, strongly prosogyrous for the tric ribs on the disk. This species is probably genus, located anteriorly at one fourth to two related to Costocyrena minor. fifths in shell length; anterior dorsal margin Occurrence and geological age:-Fine-grained weakly concave; anterior margin very short, sandstone of the basal part of the Hoji Forma nearly straight, forming nearly a right angle with tion of the Monobegawa Group at Tatsukawa of broadly arcuated ventral margin; posterior mar Katsuura-machi, Kami-katsu-gun in Tokushima gin short, subvertical, very weakly convex; pos Prefecture; Aptian. terior dorsal margin very long, nearly straight or very weakly arched; posterior carina strongly Costocyrena ohnishii, sp. nov. angulated, extended nearly straight from umbo to postero-ventral corner; lunule distinctly sepa Figures 2-1-12, 4 rated from the disk, deeply depressed; escutch Materials:-Holotype, KSG 3880, external eon very narrow but elongated; surface orna mould of left valve; paratypes, KSG 3881-KSG mented with about 7 strong concentric ribs 3883, external moulds of right valves; KSG 3884 which are narrower than their interspaces and -KSG 3885, external moulds of left valves; all very finely crenulated; hinge with typical Luci from Tatsukawa of Katsuura, Tokushima Prefec noid; inner margin smooth. ture. Paratypes, KSG 3886-KSG 3888, ex Measurements:-(in mm.) ternal moulds of left valves; KSG 3889-KSG Specimens Length Height Thickness 3895, external moulds of right valves; both from KSG 3884, I. ext. mol. 13.5 10.0 2.0 Idaira of Inasa, ShizuokaPrefecture. KSG 3881, r. ext. mol. 15.0 9.5 2.0 Diagnosis:-Shell trigonally ovate; umbo KSG 3882, r. ext. mol. 16.0 15.0 4.0 strongly prosogyrate, located at about one fourth KSG 3885, I. ext. mol. 15.0 14.0 4.0 100 Masayuki TASHIRO

Bull. Fukuoka Univ. Educ., vol. 22, no. 3, p. 256, KSG 3880, I: ext. mol. 13.0 11.0 2.0 pI. 3, figs. 1-11. 2.0 KSG 3889, r. ext. mol. 11.0 8.5 1973. Costocyrena crellatus Ohta, Ibid., vol. 22, no. 3, KSG 3890, r. ext. mol. 11.5 9.0 3.0 p. 258, pI. 3, fig. 12. KSG 3891, r. ext. mol. 14.5 11.5 3.0 1975. Costocyrena otsukai (Yabe et Nagao); Hayami, KSG 3886, I. ext. mol. 10.5 7.0 3.0 UniJ'. Mus., Univ. Tokyo, Bull., 10, p. 139. 1976. Costocyrena otsukai (Yabe et Nagao); Ohta, KSG 3892, r. ext. mol. 15.0 9.0 3.0 Atlas of Japanese fossils, vol. 44, Mesozoic Observation:-The concentric ribs on the disk bivalves, no. 3, Cr. 26, figs. 16 - 20. 1977. Costocrena otsukai (Yabe et Nagao); Matsukawa, are somewhat variable in strength but are rather Jour. Ceol. Soc. Japan, vol. 83, no. 2, pI. 1, figs. uniform in number. On some specimens, very 7,10 and 11. fine radial striae which are concerned with the 1979. Costocyrena otsukai (Yabe et Nagao); Matsu crenulations on the concentric ribs, appear on kawa,Ibid., vol. 85, no. 1, pI. 1, figs. 5-6. the outsklits of the ribs (see Figure 2-10). 1981. Costocyrena otsukai (Yabe et Nago); Ohta, Bull. Comparison: - This species resembles Costo Fukuoka Univ. Educ., vol. 31, no. 3, p. 103, pI. 7, figs. 13-34. cyrena otsukai (Yabe et Nagao in Yabe, Nagao and Shimizu, 1926), from the Shiroi Formation Materials:-KSG 3903-KSG 3904, external of the Sanchu area in central Japan, in its less moulds of left and right valves, from Yoneno developed radial striae on the disk, but the moto of Ittku, Kochi City in Kochi Prefecture. former differs from the latter in its strong and KSG 3905-KSG 3908, external moulds of left less numerous concentric ribs and more or less and right valves, from Kaganoi of Higashi-kuma, prominent umbo. Kochi City. KSG 3909-KSG 3912, external Occurrence and geological age:-Dark gray moulds of right and left valves, from Tatsukawa mudstone of the Tatsukawa Formation at Tatsu of Katsuura, Katsuura-gun in Tokushima Pre kawa, Katsuura-gun in Tokushima Prefecture; fecture. KSG 3913-KSG 3916, external moulds Upper Hauterivian. Dark gray shale of the Idaira of right valves, from Kami-koshigoe, Minami Formation at Inasa, Inasa-gun in Shizuoka Pre Amabe-gun in Ohita Prefecture. fecture; Barremian(?) or Upper Hauterivian. Measurements:-(in mm.) Specimens Length Height Thickness Costocyrena otsukai otsukai (Yabe et Nagao) KSG 3906, I. ext. mol. 16.0 12.5 2.5 KSG 3907, r. ext. mol. 17.0 11.5 3.5 Figures 1-26-30 KSG 3909, I. ext. mol. 14.0 9.5 2.5 1926. Cyrena otsukai Yabe et Nagao, in Yabe, Nagao KSG 3910, r. ext. mol. 16.0 11.5 2.0 and Shimizu, Sci. Rep. Tohoku Imp. Univ., Ser. KSG 3911, r. ext. mol. 18.0 11.0 2.0 2, vol. 9, no. 2, p. 50, pI. 2, figs. 20-24. KSG 3913, I. ext. mol. 15.5 9.0 2.5 1973. Costocyrella otsukai (Yabe et Nagao); Ohta, KSG 3912, I. ext. mol. 18.0 13.5 3.0

~ Figures 5-1-13. Costocyrena matsumotoi Hayami, x2 1. KSG 3844; 2, KSG 3845; 3, KSG 3841; 4, KSG 3846; 5, KSG 3842; 6, KSG 3847; 7, KSG 3848; 8, KSG 3843; 9, KSG 3849; 10, KSG 3850; 11, KSG 3851; 12, KSG 3852; 13, KSG 3853; Loc. Jhogusan of Miyaji, Yatsushiro City, Kumamoto Pref. 14-27. Costocyrena sp. cf C. peikangellsis Hayami, x2 14, KSG 3917; 15, KSG 3920; 18, KSG 3918; 20, KSG 3922; 21, KSG 3923; 22, KSG 3924; 26, KSG 3919; 27, KSG 3921; Loc. Kasanokawa of Okho, Ryoseki area, Nangoku City, Kochi Pref., 16, KSG 3929; 25, KSG 3928; 17, KSG 3930; 19, KSG 3927; Loc. Todai of Hasc, Kami-ina-gun, Nagano Pref., 23, KSG 3926; Loc. Idaira of lnasa, lnasa-gun, Shizuoka Pref., 24, x3, showing surface ornamentation, Loc. Kasanokawa. 28-37. Costocyrella hojiensis, sp. nov., x2 28, KSG 3876; 29, KSG 3872, paratype; 30, KSG 3871, paratype; 31, KSG 3870, paratype; 32, KSG 3875, paratype; 33, KSG 3873, paratype; 34, KSG 3869, holotype; 35, KSG 3877, paratype; 36, KSG 3879, paratype; 37, KSG 3878, paratype; Loc. Kawanishi of Kami-katsu-gun, Tokushima Pref. All the specimens are gum casts of the internal and external moulds. 832. Cretaceous Eomiodon and Costocyrena 101

9 7

12 15 11 6

20 16 22

17 27 24

30 26 18 28 25

33 31 102 Masayuki TASHIRO

Remarks:-This subspecies is one of the well known Early Cretaceous bivalves, representative of the so-called Ryoseki Fauna in southwest Japan. The concentric ribs on the disk are variable from 8 to 15 in number. Very fine radial striae or crenulations are often observable on the top or outsklits of the concentric ribs. The crenulations on the concentric ribs are described as the sub specific characters which were discriminated Cos to cyrena otsukai crenatus Ohta from C. otsukai otsukai by Ohta (l973). In so far as I can see the distinctions between them are one of the varieties of C. otsukai otsu Figure 6. Sketch of the hoiotype, Costocyrena kai. otsukai obsoleta, subsp. nov. Occurrence and geological age:-Fine-grained Diagnosis:-Shell trigonal ovate; umbo proso ~'1ndstone or silty mudstone of the upper mem gyrate, weakly prominent; surface nearly smooth ber of Ryoseki Formation of the Monobegawa except for several weak concentric ribs near Group, at Yonenomoto of Ittku and Kaganoi of umbo; posterior carina distinctly angulated. Higashikuma, both in Kochi City; Hauterivian. Description:-Shell medium in size, trigonally Dark greenish gray mudstone of the upper mem ovate, longer than high, moderately inflated; ber of the Ryoseki Formation at about 1600 m umbo small, weakly prosogyrate, a little promi north of Suita, Kami-gun in Kochi Prefecture; nent, pointed at two fifths from front of valve; Hauterivian. Greenish gray sandy mudstone of anterior dorsal margin nearly straight; anterior the Tatsukawa Formation of the Monobegawa margin well rounded; ventral margin broadly Group at Tatsukawa of Katsuura, Katsuura-gun arched; posterior margin short, nearly straight in Tokushima Prefecture; Hauterivian. Dark gray or very weakly convex; posterior dorsal margin mudstone of the upper member of Koshigoe elongated with about twice length of the anterior Formation (Haidate II Formation by Tashiro dorsal margin, weakly convex; surface nearly et al., 1983) at Kami-koshigoe of Honjho, smooth except for several weak concentric ribs Minami-Amabe-gun in Ohita Prefecture; Hau which are very narrower than their interspaces, terivian. Dark gray mudstone of the Kawaguchi occupied near the umbonal region; postero Formation at Kami-tanoura of Tanoura-machi, ventral corner obtusely angulated with nearly Ashikita-gun in Kumamoto Prefecture. The holo right angle; posterior carina distinctly angulated, type was recorded from the Shiroi Formation of extended from umbo to postero-ventral corner; the Sanchu area in central Japan. This species is escutcheon very narrow but elongated; lunule also known from the Yuasa Formation at Yuasa very narrow and short; posterior area or slope in Wakayama Prefecture. rather broad for the genus; hinge identical with that of Costocyrena otsukai otsukai (Yabe et Costocyrena otsukai obsoleta, subsp. nov. Nagao); inner margin smooth; adductor scars Figures 1-31-37,6 very weakly impressed. Measurements.-{in mm.) Materials:-Holotype, KSG 3896, external Specimens Length Height Thickness mould of left valve; paratypes, KSG 3897 - KSG KSG 3896, I. ext. mol. 16.0 11.0 4.0 3898, external moulds of left valves; KSG 3899 KSG 3897, I. ext. mol. 13.0 11.0 3.5 - KSG 3902, external moulds of right valves; all KSG 3898, I. ext. mol. 11.0 6.5 2.0 from Idaira of Inasa, Inasa-gun in Shizuoka Pre KSG 3899, r. ext. mol. 18.0 12.5 3.0 fecture. KSG 3900, r. ext. mol. 15.5 10.0 3.5 832. Cretaceous Eomiodon and Costocyrena 103

KSG 3901, r. ext. mol. 15.0 10.5 3.0 flated; umbo small, prosogyrous, weakly promi KSG 3902, r. ext. mol. 17.0 9.5 3.5 nent, located at about one third from front of valve; anterior dorsal margin shori, weakly con Observation:-In this new subspecies, the cave; anterior margin narrowly rounded; ventral umbonal concentric ribs are variable in number margin broadly arched and gradually changing and strength, and usually occupied about one into subvertical posterior margin; posterior dorsal third from the umbo in the shell height. The margin long, very weakly convex; surface orna hinge structure and internal features of the valve mented with regularly spaced concentric ribs and are entirely identical with those of Cos to cyrena very fine numerous radial striae; posterior carina otsukai otsukai (Yabe et Nagao), from the Lower weak for the genus; escutcheon narrow and Cretaceous of southwest Japan (Yabe, Nagao and lanceolate; lunule very narrow and short, dis Shimizu, 1926; Hayami, 1965; Ohta, 1973, tinctly separated from the disk by angulated 1981 ). ridge. Comparison: - This new subspecies differs Measurements:-(in mm.) from Costocyrena otsukai otsukai (Yabe et Specimens Length Height Thickness Nagao), in its nearly smooth external surface at KSG 3917, 1. ext. mol. 10.0 8.0 2.0 their adult stage. their younger stages this In KSG 3918, 1. ext. mol. 13.0 10.0 3.5 subspecies is, however, difficult to discriminate KSG 3920, 1. ext. mol. 8.0 6.0 1.0 from C. otsukai otsukai in the same diagnostic KSG 3922, r. ext. mol. 9.0 8.5 1.5 features. Although this subspecies resembles KSG 3923, r. ext. mol. 10.0 9.0 2.0 Costocyrena ohnishii, sp. nov. in its sub trigonal KSG 3930, 1. ext. mol. 8.5 7.0 1.5 outline, the former differs from the latter by its smooth surface. Observation:-Abundant specimens, mostly Occurrence and geological age:-Dark gray external and internal moulds, of this species are mudstone of the Idaira Formation at Idaira of at hand. This species is characterized by rounded Inasa, Inasa-gun in Shizuoka Prefecture; Bar outline of the valve, and weak posterior carina remian or Hauterivian. for the genus Costocyrena. The concentric ribs are somewhat variable in number, but countable Cos to cyrena sp. cf. C. peikangensis Hayami to about 15 in some specimens. They are very narrower than their interspaces and roof-shaped Figures 5-14-27 on the top. About 5 on umbonal ones are dense Compared with:- ly crowded but the other ones are widely spaced. 1965. Costocyrena peikangensis Hayami, in Matsumoto, The radial striae on the disk generally appear on Hayami and Hashimoto, Petrol. Ceol. Taiwan, no. the interspaces of the concentric ribs and its 4, p. 12, pI. 2, figs. 5 -6. number is about 4 in the breadth of 1 mm. 1975. Costocyrena peikangensis Hayami; Hayami, Univ. Comparison: - This species is very similar to Mus., Univ. Tokyo, Bull., 10, p. 140. Costocyrena peikangensis Hayami (1965) from Materials:-KSG 3917-KSG 3921, external the Lower Cretaceous of Taipei in Taiwan, in moulds of left valves; KSG 3922-KSG 3925, its nearly identical features of the valve. The external moulds of right valves; both from Kasa umbonal concentric ribs are somewhat more nokawa of Okho, Nangoku City in Kochi Prefec crowded in this species than in C. peikangensis. ture. KSG 3927 -KSG 3930, external moulds of This resembles Costocyrena minor Ohta (1981) right and left valves, from Todai of Hase, Nagano from the Miyaji Formation of central Kyushu Prefecture. KSG 3926, external mould of right in its small valve and very fine radial striae on the valve, from Idaira of Inasa, Inasa-gun in Shizuoka disk, but the former differs from the latter in Prefecture. the rounded outline and weak posterior carina. Description:-Shell small, roundly ovate in Occurrence and geological age: - Very fine outline, slightly longer than high, weakly in- grained sandstone of the upper part of Monobe 104 Masayuki TASHIRO

Formation of the Monobegawa Group at Hoku tion (Kochi), Funadani Formation (Kochi) ryo of Kasanokawa, Ryoseki area, Nangoku City and basal part of the Nakaizu Formation in Kochi Prefecture. Dark gray siltstone of the (Tokushima) of the Nankai Group in Shikoku. Ogurogawa Formation at Todai of Hase, Kami * Eomiodon matsubasensis Tamura (Lower ina-gun in Nagano Prefecture. Dark gray siltstone Cenomanian to Middle Cenomanian), Fuki or very fine-grained sandstone of the Idaira For goshi Formation (Kochi) of the Sotoizumi mation at Idaira of Inasa, Inasa-gun in Shizuoka Group in Shikoku; Mifune Group (Kuma Prefecture; Lower Barremian and Hauterivian(?). moto) and Goshonoura Group (Kumamoto), in central Kyushu. Distribution of Eomiodon and Costocyrena II. Costocyrena I. Eomiodon The stratigraphical and geographical distribu The stratigraphical and geographical distribu tions of all species of Costocyrena in the Creta tions of all species of Eomiodon from the Creta ceous of Japan are summarized as follows. ceous of Japan are summarized as follows. * Costocyrena ominensis (Nakazawa et Murata, * Eomiodon? kumamotoensis Tamura (Upper 1966) ("Neocomian": not treated in this most Jurassic or Lowest Cretaceous), Saka paper), Ohshima Formation (Miyagi) of the moto Formation (Kumamoto) of the Tori Kamihei Group in north Honshu. nosu Group in Kyushu; basal part of the A * Costocyrena otsukai otsukai (Yabe et Nagao) Member of Doganaro Formation (Kochi) of (Hauterivian) Ryoseki Formation (Kochi) and the Shimanto Terrain in Shikoku. Tatsukawa Formation (Tokushima) of the * Eomiodon matsumotoi Ohta (Lower Hau Monobegawa Group in Shikoku; Kawaguchi terivian to Barremian), "Kawaguchi" Forma Formation (KumaI!loto) and Koshigoe Forma tion (Kumamoto) of the Nankai Group(?), tion (Ohita) of the Monobegawa Group in lower part of the Yamabu Formation (Ohita), Kyushu; Yuasa Formation (Wakayama), Ogu Uminoura Formation (Kumamoto) in Kyu rogawa Formation (Nagano) and Shiroi For shu; Shobu Formation (Tokushima) of the mation (Nagano) in central Honshu. Nankai Group in Shikoku; sandstone of the * Costocyrena otsukai obsoleta Tashiro (Low "Torinosu Group" at south of Birafu (Kochi) ere?) Barremian), Idaira Formation (Shizuoka) in Shikoku; middle part of the A Member of of the Monobegawa Group(?) in central Hon Doganaro Formation (Kochi) of the Shimanto shu. Terrain in Shikoku. * Costocyrena ohnishii Tashiro (Hauterivian), * Eomiodon nipponicus Ohta ("Neocomian": Idaira Formation (Shizuoka) of the Monobe not treated in this paper), Yoshimo Forma gawa Group(?) in central Honshu, Tatsukawa tion (Yamaguchi) of the Toyonishi Group in Formation (Tokushima) of the Monobegawa west Honshu. Group in Shikoku. Eomiodon hayamii Ohta ("Neocomian": not * * Costocyrena sp. cf. C. peikangensis Hayami treated in this paper), Yoshimo Formation (Hauterivian(?) to Lower Barremian), Oguro (Yamaguchi) of the Toyonishi Group in west gawa Formation (Nagano) and Todai Forma Honshu. tion (Shizuoka) in central Honshu; Monobe * Eomiodon sakawanus (Kobayashi et Suzuki) Formation (Kochi) of the Monobegawa Group (Aptian), upper part of the Yamabu Forma in Shikoku. tion (Ohita) in Kyushu; Kaisekiyama Forma-

---+ Figure 7. Map showing the distribution of EomiC{don and Costocyre~ during Hauterivian to Ceno~ania~ in southwest Japan. C: Costocyrena. E: Eomiodon. E: Uppermost JurassIc or lowest Cretaceous Eom/Odo~. from the Torinosu and Shimantogawa Groups. Dotted line: Northern border line of the Kurosegawa TectOnIC Belt. 105 832. Cretaceous Eomiod on and Costocyrena

.1.

APTIAN

I / / f I

3 -/-;>~. .) 106 Masayuki TASHIRO

* Costocyrena radiatostriata (Yabe et Nagao) Formation of the Sotoizumi Group in Shikoku, (Upper Barremian), Yunoki Formation (Ko Eomiodon matsubasensis occurs characteristi chi) of the Monobegawa Group in Shikoku; cally but Costocyrena species are entirely lack Sebayashi Formation (Nagano) of central ing. Honshu. Temporal change of geographic distributions * Costocyrena minor Ohta (Aptian), Miyaji of two genera, Eomiodon and Costocyrena, Formation (Kumamoto), basal part of the during the Cretaceous time seem to be one of the Hinagu Formation (Kumamoto) in Kyushu; important clues to testify the presence of the basal member of the Hibihara Formation Early Cretaceous lateral fault movement of the (Kochi) of the Monobegawa Group in Shi Kurosegawa Tectonic Belt in the Chichibu koku. Terrain of Southwest Japan (Tashiro, 1985, * Costocyrena hojiensis Tashiro (Aptian), Hoji 1986). Formation (Tokushima) of the Monobegawa Group in Shikoku. References * Costocyrena matsumotoi Hayami (Albian?), Yatsushiro Formation of the Monobegawa(?) Hayami, I. (1965): Lower Cretaceous marine pele Group in Kyushu. cypods of Japan, Pt. 2, Mem. Fac. Sci., Kyushu * Costocyrena mifunensis Tamura (Lower Ceno Univ., Ser. D, Ceol., vol. 17, no. 2, p. 221-349, pIs. 27-52. manian to Middle Cenomanian), Mifune --(1975): A systematic survey of the Mesozoic Group (Kumamoto) and Goshonoura Group Bivalvia from Japan. Univ. Mus., Univ. Tokyo, (Kumamoto) of central Kyushu. Bull., no. 10, p. 1-249, pIs. 1-10. Katto, J. and Tashiro, M. (1979): A study on the mol III. Concluding remarks luscan faunas of the Shimanto Terrain, southwest In the Lower Cretaceous of Japan, the species Japan, Pt. 1: On the bivalve fauna of the Doganaro Formation in Susaki area, Kochi Prefecture. Res. of Eomiodon occur from the uppermost part of Rep., Kochi Univ., vol. 27, Nat. Sci., p. 143-150, Torinosu Group, Nankai and Shimantogawa pIs. 1-2. Groups in Southwest Japan (all of which are Kobayashi, T. and Suzuki, K. (1939): The brackish located in the southern side of Kurosegawa Welden fauna of the Yoshimo beds in Provo Naga Tectonic Belt), and Toyonishi Group in western to, Japan. Japan Jour. Ceol. Ceogr., vol. 16, nos. 3-4, p. 213-224, pIs. 13-14. Honshu. On the contrary, Costocyrena species Matsuda, T. (1985): Biostratigraphy of the Cretaceous distribute in the Monobegawa Group which Goshonoura Group of Shishijima island, Kago seems to be located in the northern side of the shima Prefecture. Fossils, no. 39, p. 1-15 (Palae Kurosegawa Tectonic Belt, in southwest Japan, onto Soc. Japan). and Shiroi and Sebayashi Formations of Sanchu Matsukawa, M. (1977): Cretaceous System in the east ern part of the Sanchu "Graben", Kwanto, Japan. area in central Japan, and Kamihei Group in Jour. Ceol. Soc. Japan, vol. 83, no. 2, p. 115-126, northeast Japan. Geographic distribution of pIs. 1-2. Eomiodon species is in a sharp contrast to that --(1979): Some problems on the Cretaceous Shiroi of Costocyrena species, separated by the Kurose Formation of the Sanchu "Graben", Kwanto gawa Tectonic Belt, particularly in the Lower Mountainous, Japan. Ibid., vol. 85, no. 1, p. 1-9, pI. 1. Cretaceous strata of southwest Japan, except Matsumoto, T., Hayami, I. and Hashimoto, W. (1965): for the Toyonishi Group which is located at Some molluscan fossils from the buried Cretaceous northern side of the Median Tectonic Line. of western Taiwan. Petrol. Ceol. Taiwan, no. 4, p. The Upper Cretaceous species of Eomiodon 1-24, pIs. 1-2. --, Kanmera, K. and Ohta, Y. (1980): Cephalopod and Costocyrena occur together at some locali faunule from the Cretaceous Yatsushiro Forma ties in central Kyushu: i.e., the Goshonoura and tion (Kyushu) and its implications. Trans. Proc. Mifune Groups. In these areas, Eomiodon is more Palaeollt. Soc. Japan, N. S., no. 118, p. 325-338, predominant than Costocyrena. In the Fukigoshi pI. 37. 832. Cretaceous Eomiodon and Costocyrena 107

Nakazawa, K. and Murata, M. (1966): On the Lower stratigraphy of the Cretaceous in Japan. Ceol. Cretaceous fossils found near the Omine mine, Soc. Japan, Mem., no. 26, p. 43-75. Iwate Prefecture, northeast Japan. Mem. Coil. --(1985b): The Cretaceous System of the Chichibu Sci., Univ. Kyoto, Ser. B, vol. 32, no. 4, p. 303- Belt in Shikoku - On the Early Cretaceous lateral 333, pIs. 3-6. fault in the Chichibu Belt -. Fossils, no. 38, p. Ohta, Y. (1973): Pelecypod family Neomiodontidae 23-35 (Palaeont. Soc. Japan). from the Lower Neocomian of Japan. Bull. Fuku --(1986): Paleobiogeography and paleoecology of oka Univ. Educ., vol. 22, no. 3, p. 245-273, pIs. the Cretaceous System of Southwest Japan. Ibid., 1-4. no. 41, p. 1-16. --(1976): Atlas of Japanese fossils, vol. 44, Meso --and Katto, J. (1986): Upper Jurassic molluscan zoic bivalves (3), Tsukiji-shokan. fossils from the Shimanto Belt in Shikoku. Res. --(1981): Some Lower Cretaceous Corbiculidae and Rep., Kochi Univ., vol. 34, p. 121-127, pI. 1. Neomiodontidae (Bivalvia) from Japan. Bull. Fuku --, Kozai, T., Okamura, M. and Katto, J. (1980): A oka Univ. Educ., vol. 31, no. 3, p. 103-134, pIs. biostratigraphical study of the Lower Cretaceous 1-8. Formations of Monobe area, Kochi Prefecture, --and Monji, N. (1976): On the Lower Cretaceous Japan. Ceol. Paleont. Shimanto Belt, Taira and Uminoura Formation in Kyushu. Ibid., vol. 26, no. Tashiro eds., Kochi, p. 71-82, pIs. 10-11. 3,p.117-136. - and Matsuda, T. (1982): The bivalve fossils from Tamura, M. (1959): Trigoniidae, Ostreidae, Bakevel the Cretaceous Fukigoshi Formation of the Mono Iiidae, Pteriidae, Cardiidae and Astartidae from the be area, Shikoku. Trans. Proc. Palaeont. Soc. Upper Jurassic Sakamoto Formation in central Japan, N. S., no. 127, p. 393-418, pIs. 62-65. Kyushu, Japan. Trans. Proc. Palaeont. Soc. Japan, --, Tanaka, H. and Matsuda, T. (2983): The strati N. S., no. 33, p. 23-32, pI. 5. graphy of the Cretaceous System of Haidate-yama --(1960): Upper Jurassic pelecypods from the Tori area, Oita Prefecture. Res. Rep., Kochi Univ., vol. nosu Group in Shikoku, Japan. Mem. Fac. Educ., 32,Nat. Sci., p. 47-54. Kumamoto Univ., vol. 8, p. 227 -244, pI. 2. Yabe, H., Nagao, T. and Shimizu, S. (1926): Cretaceous --(1977): Cenomanian bivalves from the Mifune molluscan from the Sanchu Graben in the Kwanto Group, Japan. Part 2, Ibid., vol. 26, p. 107-144, mountainland, Japan. Sci Rep., Tohoku Imp. pIs. 1-13. Univ., Ser. 2, vol. 11, no. 1, p. 27-100, pIs. 3-9. Tashiro, M. (1985a): The bivalve faunas and their bio-

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833. THE THIRD ADDITION TO THE SILURIAN TRILOBITE FAUNA OF YOKOKURA-YAMA, SHIKOKU, JAPAN

TEIICHI KOBAYASHI The Japan Academy, Ueno Park, Tokyo

and TAKASHIHAMADA Department of Earth Science and Astronomy, College of Arts and Sciences, University of Tokyo

Abstract Seven species of trilobites including two new genera and three new species are here described from Mt. Yokokura. Metaleiolichas and Paraleiolichas are two new genera, each represented by a new species. A new species of Japonoscutellum is added to them. Two pygidia are new to the two known species and one pygidium is so well preserved that it is capable of emending the existing description. Finally, a free cheek is a new find of a species for its locality. Thus the previous knowledge of the Yokokura-yama fauna is well advanced with all of these specimens.

A new collection of trilobites from Mt. Yoko the cephalon has been imperfect. Therefore its kura contains 7 species in 7 genera and 5 fami description is here emended with a better speci lies, i.e. the Scutelluidae, Illaenidae, Cheiruridae, men. Encrinuridae and Lichidae as follows: All specimens of the collection were derived 1: Japonscutellum tunidum, sp. nov. from Gomi limestone quarry except for the free 2. Bumastus glomerosus Kobayashi and Hamada, cheek of Encrinurus subtrigonalis from Sugihara. 1974 This new occurrence confIrms the contention 3. Cerauroides orientalis Kobayashi and Hamada, that the Gomi and Sugihara trilobites horizons 1973 are inseparable. 4. Encrinurus subtrigonalis Kobayashi and The authors record here their best thanks to Hamada, 1985 Dr. Jiro Katto, Professor Emeritus of Kochi 5. Metaleiolichas tuberculatus, gen. et sp. nov. University for presentation of the new collec 6. Paraleiolichas globulus, gen. et. sp. nov. tion. 7. Dicranopeltis tricorn is Kobayashi and Hamada, 1986 Family Scutelluidae R. and E. Richter, 1955

Thus the collection contains three new species Genus Japonoscutel!um Pl'ibyl and Van~k, 1971 and two new genera, namely, Metaleiolichas and Japonoscutel!um tumidum, Paraleiolichas of the Lichidae. Among the known sp. nov. species pygidia have been unknown of Cerauroi Figures 3-3a-c des orientalis and Dicranopeltis tricorn is. Of Description:-Pygidium semiparabolic in out Bumastus glomerosus the associate pygidium to line and distinctly vaulted with the top at about one-fourth from anterior margin and depressed *Received October 29,1986; Studies on Japanese Trilo near periphery; axial lobe sub trigonal, one-fifth bites and Associated Fossils-XLVIII.

109 110 Teiichi KOBA YASHI and Takashi HAMADA

as broad as anterior margin; its median part dis Family Cheiruridae Hawle and Corda, 1847 tinctly elevated above lateral parts; median rib Genus Cerauroides Prantl and Pl'ibyl, 1946 similar to seven lateral ones on each side in breadth and prominence in anterior, but more Cerauroides orienta lis Kobayashi and Hamada broadened and bifurcate in posterior; all ribs Figures 1-C, 2-3 crossed by concentric lirae; pleural furrows narrower than ribs near axial lobe, but becoming 1973. Cerauroides orientalis Kobayashi and Hamada, Proc. Japan Acad., v. 47, no. 8, p. 547, text-figs. much wider near postero-Iateral margin. 1-5. Comparison:-This pygidium is tentatively 1974. Cerauroides orienta lis Kobayashi and Hamada, referred to Japonoscutellum, because it resem Palaeont. Soc. Japan, Spec. Pap., no. 18, p. 84, bles Japonoscutellum japonicum and J. genicula pI. 6, figs., 1-4, text-fig. 6A. tum in outline and some other aspects. The pyg The pygidium is composed of four segments; idium is slanting at about one-third from the pos axial lobe a little broader than one-third of pyg terior periphery in J. genicula tum Kobayashi idium, but its relative breadth reducing posteior and Hamada, 1985. Incidentally, the median rib ly; first pleura very large and produced back into is bifurcate in this specimen as well as J. japon a long spine; second pleura of moderate size ter icum as seen in the pygidia in fig. 5, pI. 4 and fig. minating at a minute spine; succeeding two 15, pI. 5 (Kobayashi and Hamada, 1974). pleurae fused and embracing posterior part of Occun-ence:-Limestone, Gomi Quarry, KochL axis; two large posterior spines only a little diver gent backwards; test smooth. Family Illaenidae Hawle and Corda, 1849 Compared to Cerauroides lunshanensis Genus Bumastus Murchison, 1839 (Grabau, 1924) the first pair of pleural spines Bumastus glomerosus Kobayashi and Hamada are not so widely divergent and the second pair of spines rudimentary in this species. Otherwise Figures 1-A, 2-1a-d both of them have the construction very similar 1974. Bumastus glomerosus Kobayashi and Hamada to each other. In the slight divergence of the pos Palaeont. Soc. Japan, Spec. Pap., no. 18, p. 47: terior spines it is nearer to the pygidium of pI. 1, figs. 3 -8, text-fig. 2A. Ceraurinium intermedium (Kielan, 1955) from the Ashgillian of Poland, but the spines are Pygidium more or less elliptical, but more well straight and the posterior margin of the pygidium rounded on posterior side than the other, its is entire in that species. ratio of length to breadth being 11 to 25; maxi This pygidium belongs probably to either mum breadth through near one-third of length Cerauroides orientalis or C. elongatus both of from anterior margin where it is most convex· which occur at Gomi quarry where the pygidium convexity there corresponding to about a half of was collected. It is provisionally located in the pygidial length; axial lobe limited by distinct former species simply because, it is more com depressions on its lateral sides half as wide as mon and better known than the latter species. It pygidium. is noted here that the hypostoma of Cerauroides The pygidium here described is better pre orientalis is closely allied to that of Ceraurinium served than the two above cited (1974). The intermedium, although the posterior margin is anterior margin is broadly arcuate, instead of sinuated in C. orientalis. straight as previously restored in text-fig. 2A. Occun-ence:-Limestone, Gomi Quarry. This pygidium is simply convex without flat tened marginal border as in the previous descrip Family Encrinuridae Angelin, 1854 tion. Only very fine striae are discernible near the margin. Otherwise the test is smooth. Genus Encrinurus Emmrich, 1844 Occun-ence:-Limestone, Gomi Quarry. Encrinurus subtrigonalis Kobayashi and Hamada 833. Silurian Trilobites of Shikoku 111

Figure 1. Reconstruction of five trilobite species from Yokokura-yama. A. Bumastus glomerosus Kobayashi and Hamada, 1974, x6; B. Metaleioleichas tuberculatus, gen. et sp. nov., x5; C. Cerauroides orienta lis Kobayashi and Hamada, 1973, x3; D. Dicranopeltis tricorn is Kobayashi and Hamada, 1986, x3; E. Paraleiolichas globulus, gen. et ep. nov., x8.

Figures 3-2a, b A right free cheek of Encrinurus has an eye 1985. Encrinurus subtrigonalis Kobayashi and Hamada, of medium size from which the proparian facial Trans. Proc. Palaeont. Soc. Japan, N. S., no. 139, suture extends to the lateral margin of the cepha p. 210, pI. 28, figs. 4a-c, pI. 29, figs. 2a-d. Ion. It is densely granulate and most granules; 11 2 Teiichi KOBA YASHI and Takashi HAMADA 833. Silurian Trilobites of Shikoku 113 have a central pit. This is the characteristic tex in the inner side in Paraleiolichas. ture of the cephalon of Encrinurus subtrigonalis. Therefore this is the new find of this species at Genus Metaleiolichas, gen. nov. Sugihara. Occurrence: -Tuffaceous sandy shale; Sugi Generic characteristics are included in the hara. description of the monotypic species.

Family Lichinae Hawle and Corda, 1874 Metaleiolichas tuberculatus, sp. nov. The group of Leiolichas Schmidt, 1885 in the Figures I-B, 3-4a-c Lichidae was represented only by Lichas illae An imperfect cranidium having median lobe, noides Nierzkowsky, 1857 which occurs in the a narrow bicomposite left lobe and a small left Upper Ordovician in East Baltic region and also basal lobe which are all outlined clearly by per in North Germany in Ordovician boulders. Its sistent furrows; median lobe strongly convex, shield is quite smooth and the furrows are weak, broad and much more expanded in anterior although they are distinct in casts. Later Warburg than posterior; bicomposite lobe narrowing back (1939) described Leiolichas illaenoides from the ward, strongly convex, but its top near longitudi Macrourus limestone of Oland found in boulders. nal furrow a little below median lobe; basal lobe The two genera, Metaleiolichas and Paraleio fusiform, elongated laterally. Axial furrow, pos lichas, proposed here best agree with Leiolichas terior marginal furrow and terminus of OCCipital in the fundamental configuration of the crani furrow are all preserved. Surface ornamented dium, but they are different from that genus in with tubercles of different sizes except for fron the median lobe much larger, the median, bicom tal rim and furrows. posite and basal lobes each forming a swell, their This· cranidium agrees with Leiolichas in the boundary furrows all strongly excavated in their fundamental configuration, but the median lobe whole length and the surface densely granulate. is incomparably developed, longitudinal furrow In Leiolichas, on the contrary, the test is smooth, persistent in its whole length and the test densely the median lobe relatively narrow, this lobe con tuberculate. stitutes the same dome with lateral and basal Occurrence:-Limestone, Gomi Quarry. lobes and the longitudinal furrows become obso lete near the occipital ring. Genus Paraleiolichas, gen. nov. These two new genera differ from each other in the general outline of the cranidum and the Paraleiolichas globulus, sp. nov. mode of its division into lobes, as detailed later. Figures l-E, 2-4, 3-1a-b An additional distinction is found in the periph ery of the cephalon. It is represented by non Cranidium globular; median lobe subcylin tuberculate rim and strong marginal furrow in drical in middle part, but a little expanded in Metaleiolichas and by a depressed and tubercu posterior and remarkably flaring in anterior; bi late band on the outer side and the linear furrow composite lobe semiglobular and medium sized;

+- Figures 2-1a-d. BUTlUlstus glomerosus Kobayashi and Hamada, 1974, dorsal, anterior, posterior and left lateral views of a well-preserved pygidium. x6.S PA18089. . .. 2. Dicranopeltis tricorn is Kobayashi and Hamada, 1986, a dorsal view of an Incomplete pygldlllm. x3.4 PA 18092. 'd' 3 5 3. Cerauroides orientalis Kobayashi and Hamada, 1973, a dorsal view of an incomplete pygl mm. x . PA 18090. 4. Paraleiolichas globulus, gen. et sp. nov., a posterior view of the holotype caranidium. x6.S PA 18094. (vide Figures 3-1a, b) 114 Teiichi KOBAYASHI and Takashi HAMADA 833. Silurian Trilobites ofShikoku 115

basal lobe relatively large and trigonally ovoid; side, there is the posterior band of the third these glabellar lobes and fixed cheek all granulate pleura. All of them are, however, exfoliated in and completely separated from one another by posterior where the doublure of similar breadth deep furrows; frontal border flat, depressed, as that of D. scabra is exposed. In tracing terrace granulate and limited inside by linear furrow. lines it is recognizable that the third pleura is Compared to Metaliolichas this cranidium is ending at a short spine. The most important dis longer in outline, its basal lobe much larger in tinction of this pygidium from D. scabra lies in comparison with the bicomposite lobe. Neverthe the possession of a stout spine as shown by its less, they have same pattern and quite distinct scar on the third axial ring. Like the cephalon of from Leiolichas in the development of the this species fine granules are distributed densely median lobe, persistent glabellar furrrows and on the surface. dense granulation or tuberculation. Occurrence:-Limestone, Gomi Quarry. Occurrence:-Limestone, Gomi Quarry. References Genus Dicranopeitis Hawle and Cords, 1974 Dicranopeltis tricomis Kobayashi and Hamada Grabau, A. W. (1924): Stratigraphy of China, Part 1, Palcozoic and Supplement. 538 pp., 6 pis. Figures 1-0, 2-2 --(1925): Summary of the fauna from the Sintan shale. Bull. Ceol. Surv. China, no. 7. 1986. Dicranopeltis tricorn is Kobayashi and Hamada, Kielan, Z. (1955): A ncw trilobite of the genus Ceraurus Trans. Proc. Pal. Soc. Japan, N. S., no. 143, p. and the significance of cephalic spines in the onto 458, pI. 92, figs. la-g, text-figs. CI-3. geny and phylogeny of trilobites. Acta Ceol. PoL, v. 5, (2), p. 215-240. This species was instituted with a cephalon --(1959): Upper Ordovician Trilobites from Poland resembling Dicranopeitis scabra, but having a and some related forms from Bohemia and Scan median spine issuing from the top of the glabella dinavia. Palaeont. Pol., no. 11, 198 pp., 36 pis. besides a pair of long genal spines. The pygidium Kobayashi, T. and Hamada, T. (1973): Brief notes on Silurian trilobites from Mt. Yokokura, Shikoku now at hand is such a fragmentary specimen in Island. Proc. Japan A cad. , v. 49, no. 7, p. 540-544. which only the axial part is preserved. It is, how --and -- (1974): Silurina Trilobites of Japan in ever, astonishing that it coincided with the pyg comparison with Asian, Pacific and other faunas. idium of D. scabra so nicely as shown in text Palaeont. Soc. Japan, Spec. Pap., no. 18, 155 pp., fig. 4. 12 pis. - and -- (1985): Additional Silurian trilobites to The axial lobe of this pygidium consists of the Yokokura-yama fauna from Shikoku, Japan. two axial rings which are very short (sag.) and Trans. Proc. Pali1eont. Soc. Japan, N. S., no. 139, well defined by deep ring furrows, the third axial p. 206-217, pis. 28-30. ring which is so large that two rings can be fused - and -- (1986): Thc second addition to the Silurian Trilobites Fauna of Yokokura-yama, and the long terminal piece which is gradually Shikoku, Japan. Ibid., no. 143, p. 447-462, pis. tapering back without any lateral expansion as 90-92. seen in D. scabra. The third pleura is divided into Phleger, F. B. Jr. (1936): Lichian trilobites. Jour. Pale two bands by an interpleural furrow as seen on ont., v. 10, p. 593-615, figs. 1-83. the left side of the terminal piece. On the other --(1937): Further notes on thc Lichadacea. Ibid., v.

~ Figures 3-1a, b. Paraleiolichas globuills, gen. ct sp. nov., dorsal and frontal views of the holotype crani 'dium. x6.5 PA 18094. (vide Figure 2-4). 2a, b. Encrinurus subtrigol1alis Kobayashi and Hamada, 1985, a free cheek (inner mOUld). x3.5 PA 18091. 3a-c. Japonoscutellum tunidum, sp. nov., dorsal, left lateral and posterior views of hte holotype pygidium. x3.3 PA 18088. 4a-c. Metaleiolichas tllberculatlls, gen. et sp. nov., frontal, dorsal and left lateral views of the holotype cranidium. x6.6 PA 18093. 116 Teiichi KOBA YASHI and Takashi HAMADA

11, p. 253-256. Schmidt, Fr. (1885): Revision der Ostaltischen Silurien -(1937): New Lichadacea in the collection of the Trilobiten, Abt. 2, Acidaspiden und Lichiden. Museum of Practical Zoology. Harvard Univ. Mus. Mem [,Acad. Imp. de Sci. St.-petersbourg, VIle, Compo Zool. Bull., v. 80, p. 415-425, pIs. 1-2. Ser. Tom. 31, no. 1,127 pp., 6 pIs. Plibyl A., Vanek, J. and Pek, I. (1985): Phylogeny and Warburg, E. (1939): The Swedish Ordovician and Lower taxonomy of Family Cheiruridae (Trilobita). Acta Silurian Lichidae. KungL Sevenska Veten.-Akad. Univ. Aoakckiana Olomucensis, Rac. Rerum Natur. Handl., 3 Ser, Bd. K7, no. r, 162 pp., 14 pIs. Geogr.-Geol., 24, v. 83, p. 107-193 (8 pIs.).

~oo~*w~~~e~~~W~~.3~~:*~~K~5W7~K~~~7~~E~L~~~o -t~ ? ~~::. 2 fi~ Metaleiolichas, Paraleiolichas iJ~~ IJ, ~t::.fi~~::.£--::)\"~ \" ~o -t~ff!!t::. 1 fi~iJ~~~o ~~~ 4 ~JfI~::.~~tlRiJ~fit.:t::.~U-? t.: ~ ~ 2~, ~tlR~~ff'&Rrt.ct.:6bt::'JlUD~Bc ~~fftnE~~ ~ ~, -t L ~£::!tl!.!: L ~fi L\" ~ OJt.c CiJt~ IJ, foJ.tL ~ iJtfi%IJ!~#1.m L ~\"~o 'J':fHi-, ~EE~± Trans. Proc. Palaeont. Soc. Japan, N. S., No. 147, pp. 117-130,5 Figs., October 30,1987

834. EARLY CARBONIFEROUS EOSTAFFELLA (PRIMITIVE FUSULINACEA) FROM THE ICHINOTANI FORMATION, FUKUJI DISTRICT, CENTRAL JAPAN*

SHUn NIKO

Department of Earth Science and Astronomy, College of Arts and Sciences, The University of Tokyo, Komaba, Tokyo 153

Abstract. The lower part of the Ichinotani Formation at Fukuji, Gifu Prefecture, central Japan contains a very rich assemblage of foraminifers. Eostaffella (primitive fusulinacea) is described here to provide a basis for the precise biostratigraphic su bdivision and age-determina tion of the lower Ichinotani Formation. The eostaffelloids consist of eight species including three new species, i.e., Eostaffella excavata, E. igoi and E. subulba. This assemblage permits recognition of Igo's Eostaffella kanmerai zone ranging from latest Visean to early Serpukhovian (Namurian A) in age.

Introduction

Eight species of eostaffelloid fusulinaceans are described in this paper from the lower part of the Ichinotani Formation in the Fukuji dis trict, Gifu Prefecture, central Japan. The Ichino tani Formation is exposed mainly in the Ichino tani Valley, Mizuboradani Valley and lower course of the Mizuyagadani Valley in a series of NEE-SWW trending small faulted blocks, and comprises about 350 m thick of predominatingly carbonate rocks of late Early Carboniferous to Early Permian in age. Material for systematic study was collected from two localities as listed below and shown in Figure 1. Locality A: Middle course of the Ichinotani Valley. Locality B: On the mountain slope facing south of the same valley. The continuous outcrops at the locality A allow 1km to measure a complete columnar section and to CONTOUR determine the occurrence-boundary of many INTER VA L 50M fossils, although in the locality B outcrops are Figure 1. Map showing the fossil localities. *Received October 30, 1986; reviscd manuscript ac cepted Septembcr 18, 1987.

117 118 Shuji NJKO

~NS61 ~ o o

~NS54 "'-- NS48 - s ma II fa ult- "'- NS 19 l- L NS40 "'- NS46

~ "'--NS18 ~NS35 "'--NS41 :::l

~ "'---- N 5 42 oq: - ""--- T2 5 " I- I- o ~

- "'-- NS 12

v v v 1 S "'-- NS43 ~ m "'--NS 10 2 l:o~ T I6 ~ 0'· .~ . 0

7 ~3 v v Dv

122~:J--- fa u I t --- 4 ~NS10 8

Figure 2. Columnar sections showing the lithology and stratigraphic positions of samples at locality A, the middle course o f the Ichinotani Valley. 1: thick-bedded limestone; 2 : thin bedded limestone; 3 : thin alternating beds of limestone and shale; 4 : shale; 5 : limestone with chert concretions; 6 : conglomerate ; 7: dyke rock; 8 : sample number and locatio n, 834. Eostaffella from the Jchinotani Formation 119

poor due to thick vegetation. The other purpose conglomerate is characterized by the predomi of this article is to analyze stratigraphic distribu nance of ill-sorted and sub angular volcanic frag tion of foraminifera for a basis of biostratigraph ments of acidic composition (Niko et al., 1984). ic subdivision and precise correlation with the Most of the carbonates of Unit 1 is made up of faunal successions in the standard areas of Upper skeletal grains, peloids, and with extra clast and Lower Carboniferous boundary in West (acidic volcanic fragments), and are predomi Europe and U.S.S.R. natingly packstone and wackestone with minor Accounts of the foraminiferal successions of amounts of grainstone and lime mudstone. this formation have been presented by Igo (1956, Besides the rich assemblage of foraminifers, 1957), Niikawa (1978, 1980), Igo and Adachi these limestones contain many corals including (1981a), Igo, Adachi and Igo (1984), Adachi Kueichouphyllum, Dibunophyllum, Hetero (1985) and Niko (1985, 1986). Further, litho caninia, Neokoninckophyllum, Siphonodendron stratigraphically, Igo and Adachi (1981a) and and others (Kato, 1959; Igo and Adachi, 1981b Adachi (1985) divided the Ichinotani Formation etc.), and such other fossils as productid brachio into three members, 61 Unit-beds. The primitive pods (Tazawa and Kato, 1986), bryozoans (Saka fusulinacean assemblage of the present study is gami, 1960), trilobites, crinoids and ostracods. related with the lowest Unit 1 ofIgo and Adachi's Specimens used in this study are stored in the scheme, and thus it falls within the lowermost following institutions: fusulinacean zone of Eostaffella kanmerai zone, IGUT Institute of Geoscience, The Univer which probably ranges from latest Visean to sity of Tsukuba. early Serpukhovian (Namurian A) in age (Niko, UMUT University Museum, The University of 1986). Tokyo. At the type section (locality A) Unit 1 of this formation is 9.5 m thick, and is composed of a Systematic paleontology (basal?) conglomerate bed of 1.5 m thick being succeeded by a thin bedded black to dark-gray Family Eostaffellidae Mamet in Mamet, limestone (6.3 m) and further by an alternation Mikhailov and Mortelmans, 1970 of limestone and thin shale (1.7 m). The (basal?) Genus Eostaffella Rauzer-Chernousova, 1948

Table 1. Occurrences of Eostaffella in the Ichinotani Formation. The stratigraphic positions of samples are shown in Figure 2, except for samples from "float blocks" (*) of limestone.

Locality A Locality B Sample No.

* Taxon OM N N co \D 0 co "

Eostaffella excavata x x x x x x x x x x x x x E. igoi x x x E. kanmerai x x x E. mosquensis x x x x

E. cf. postmosquensis x x E. subulba ? x x E. tenebrosa x x

E. sp. x 120 ShujiNIKO

Type species:-Staffella (Eostaffella) para Description :- Test is small , discoidal, with struvei Rauzer-Chernousova, 1948. broadly umbilicate on both sides. Periphery is bluntly pointed in the inner volutions but the Eostaffella excavata Niko, sp. nov. last volution of the mature specimens has a Figures 3-A- H rounded periphery. The holotype (Figure 3-A) contains 5 volutions that is 0.l95 mm in length Material studied:-Holotype, UMUT PF 18013 and 0.46 mm in width; form .ratio is 0.42. Radius (sample NS 40, Figure 3-A); para types UMUT PF vectors of the third to fifth volutions of the holo 18014 (sample NS 40, Figure 3·B), 18015 (sam type are 0.08, 0.l5 , and 0.26 mm, respectively. ple NS 42, Figure 3-F), 18016 (sample T2 5, The initial 1 to 1 1/2 volutions are skew at nearly Figure 3-C), 18017 (sample T2 5, Figure 3-E), 90 degrees to the remaining essentially planispiral 18018 (sample T2 5, Figure 3-D), 18019 (sample whorls. The last volu tion is partially evolute. NS 41 , Figure 3-H), 18020 (sample T2 5, Figure Proloculus is nearly constant in size in the ex 3-G). In addition to the holotype and paratypes, amined specimens, being 0.017 to 0.019 mm in some other specimens were studied. All the speci· its inside diameter. Wall , approximately 0.008 mens were obtained from loc. A. mm thick in the outer volutions, consists of a Diagnosis: - Small Eostaffella with discoidal tectum, and lower and upper tectoria. Septa are test, broadly umbilicate on both sides, and long, slightly curved , and inclined forward. rounded periphery in the last volution. Coiling Septal counts of the second to forth volutions plectogyroid in juvenarium, becoming planispiral of a paratype (Figure 3-H) are 9 , 11 , and 12, in outer volutions. Septa long, slightly curved. respectively. Tunnel is low and narrow. Asym-

Figure 3. A- H, Eostaffella excavata, sp. nov. A, axial section of the holotype, UMUT PF 18013. B, tangential section of a paratype, UMUT PF 18014 . C, axial section of a paratype, UMUT PF 18016. D, axial se ction of a paratype, UMUT PF 18018. E, axial section of a paratype, UMUT PF 18017. F, axial section of a para type, UMUT PF 18015. G, neary sagittal section of a paratype, UMUT PF 18020. H, sagittal section of a paratype, UMUT PF 18035 . I-K, Eostaffella cf. postmosquensis Kireeva. I, axial section, UMUT PF 18035. J, slightly diagonal section, UMUT PF 18036. K, axial section, UMUT PF 18037. All specimens XI00. 834. Eostaffella from the Ichinotani Formation 121 metrical chomata are present in the outer volu straight to slightly concave lateral slopes. Coil tions. Aperture is low and basal. ing more or less planispiral. Spirotheca relatively Remarks:-This new species belongs to Eostaf thick. Septa short and straight. Chomata well fella of the group E. pseudostruvei that consists developed. of the following species: Description:-Test of Eostaffella igoi, sp. nov. pseudostruvei (Rauzer-Chernousova and is larger for the genus, and discoidal to lenticular Beljaev, 1936) shape with umbilicate on both sides. Umbilicus p. var. angusta Kireeva, 1951 is relatively well-developed in the last volution. p. var. chomatifera Kireeva, 1951 Periphery is pointed in axial section and lateral p. var. elegantissima Manukalova, Il'ina and slopes are nearly straight to slightly concave. Serezhikova, 1969 Mature specimens of 5 1/2 volutions are 0.36 to p. var. losovskensis Manukalova, Il'ina and 0.38 mm in length and 0.65 to approximately Serezhikova, 1969 0.73 mm in width, giving form ratios of approxi excavata Niko (this report) mately 0.52. Radius vectors of the first to fifth Eostaffella excavata is most closely allied to volutions of the holotype (Figure 4-C) are 0.04, E. pseudostruvei var. angusta Kireeva from the 0.08,0.12,0.20, and 0.32, respectively. Proloc lower Bashkirian of the Donetz Basin and Rus ulus is approximately 0.030 mm in inside diam sian Platform of U.S.S.R. in essential features, eter. Coiling is more or less planispiral. Septa but the former is different from the latter in are short, straight and usually inclined forward. having smaller proloculus. The present species Septal sutures are slightly depressed in the outer somewhat resembles E. pseudostruvei var. volutions. Septal counts of the first to fifth volu chomatifera Kireeva, but E. excavata differs in tions of a paratype (Figure 4-E) are 5,9,10,13, its smaller size and by its weaker chomata, and and 14, respectively. Wall is calcareous, micro more round·ed periphery in the last volution. granular and approximately 0.010 to 0.013 mm Evolute coiling of the last volution suggests thick in the outer volutions. It is differentiated an assignment of this species to other genera, into thin tectum, and lower and upper tectoria. especially Millerella and Zellerina. However, this Supplemental deposits, in form of an asymmet form differs from Millerella by its plectogyroid rical chomata, are well-developed in the outer coiling in juvenarium and less numerous septal volutions. Tunnel is relatively high and narrow. counts; and from Zellerina by its bluntly pointed Aperture is low, basal and simple. periphery in the inner volutions and well differ Remarks:-Eostaffella igoi somewhat resem entiated spirotheca. bles E. kanmerai (I go) from the Ichinotani For mation and E. oregonensis Sada and Danner from Eostaffella igoi Niko, sp. nov. the Late Mississippian (Chesterian) Coffee Creek Formation of central Oregon. E. kanmerai, how Figures 4-A-E ever, has a smaller shell and lower form ratio, Material studied:-Holotype, UMUT PF 18021 and its coiling is somewhat irregular. E. oregon (sample T2 5, Figure 4-b); paratypes, UMUT PF ensis has a lower form ratio, weaker chomata, 18022 (sample T2 5, Figure 4-A), 18023 (sample and deeper umbilical depression. In the general T2 5, Figure 4-D), 18024 (sample T2 5, Figure shape of E. columbiana Sada and Danner from 4-C), 18025 (sample T2 5, Figure 4-E). In addi British Columbia somewhat resembles examined tion to the holotype and paratypes, some other specimens which nevertheless have smaller num specimens were studied. All specimens from loco bers of shorter septa. Illustrated specimens of A except for two ill-oriented specimens that E. columbiana suggest the presence of diapha were obtained from loco B. notheca. There would be some possibility that Diagnosis:-Large Eostaffella with discoidal to this species might belong to a genus Pseudoendo lenticular test, pointed periphery and nearly thyra. 122 ShujiNIKO 834. Eostaffella from the Ichinotani Formation 123

Eostaffella kanmerai (Igo) Eostaffella mosquensis Vissarionova, 1948, p. 222, pI. 14, figs. 4-6; Ganelina, 1951, p. 188-189, pI. 2, Figures 4·H-J figs. 1-2; Brazhnikova et al., 1956, pi. 15, figs. 9- 11; Golubtsov, 1957, p. 165-166, pI. 9, figs. 20-21; Millerella kanmerai Igo, 1957, p. 175-177, pI. 1, figs. Durkina, 1959, p. 196-197, pI. 20, fig. 10; Bogush 20-26, pI. 2, fig. 14. and Iuferev, 1962, p. 172, pI. 6, fig. 26; Rozovskaia, Eostaffella kanmerai (Igo): Sada, 1964, p. 230-231, pI. 1963, p. 93-94, pI. 16, figs. 16-17,pl.I7,figs. I- 21, figs. 8,16-17; Sada, 1967, p. 144-145, pI. 12, 5; Manukalova-Grebeniuk, Il'ina and Serezhnikova, figs. 1-10; Sada, 1969, p. l20-121, pI. 12, figs. 1- 1969, p. 25, pI. 9, figs. 9-12; Malakhova, 1972, p. 12, 13?, pl. 13, figS. 1-2; Reitlinger, 1973, p. 62, 40, pi. 7, figs. 1-3; Ivanova, 1973a, pI. 7, fig. 6; Wu, pI. 10, figS. 18-19, pI. 11, figs. 5-6; Sada and Chang and Ching, 1974, pl. 4, fig. 10; Ozawa, 1976, Danner, 1974, p. 259-261, pI. 37, figs. 1-3,5,18- p. 121-122, pI. 22, figs. 1-15, 16?, 17-19; Nii 19; Sada, 1975, p. 35-36, pl. 8, figs. 1-5; Niikawa, kawa, 1978, p. 538, pI. 1, figs. 5-7, 15; Rich, 1980, 1978, p. 538, pI. 1, figs. 11-12; Sada, 1980, p. 68- p. 41, pI. 18, figs. 13, 15-16, 20, 25; Matsusue, 69, pI. 1, figs. 1-5, 11-13; Rich, 1980, p. 40-41, 1986, pI. 6, figs. 1-2. pI. 18, figs. 6, 8-12, 14?; Sada, Nomura and Oho, Eostaffella mosquensis mosquensis Vissarionova: 1984, p. 390-391, pI. 75, figs. 1-8. Vachard, 1977, pI. 5, fig. 23. Eostaffella cr. kanmerai (lgo): Massa and Vachard, Eostaffella mosquensis acuta Rauzer-Chernousova, 1948, 1979, pi. 6, fig. 5. p. 236-237, pI. 14, fig. 5; Ganelina, 1951, p. 190- Material studied:-Four specimens (UMUT PF 191, pi. 2, figs. 3-4; Brazhnikova et al., 1956, pI. 15, figs. 5-7; Golubtsov, 1957, p. 166-167, pI. 9, 18026, sample NS 18, Figure 4-H; 18027, sample figs. 22-25; Vachard, 1977, pI. 5, fig. 22. NS 54, Figure 4-1; and two unfigured specimens) Eostaffella acuta Rauzer-Chernousova: Armstrong and are referred to this species. Marnet, 1977, p. 85. Remarks:-Here no description of this species is given, because none of the well-oriented and Material studied:-Specimens induding four axial sections (UMUT PF 18032, sample NSR 5, complete materials were recovered during the Figure 5-G; 18033, sample DC 19, Figure 5-D; present study even they came from the type 18034, sample NSR 5, Figure 5-F; and one un locality. figured specimen), one tangential section, and The combination of morphological features of one sagittal section (UMUT PF 18070, sample this species suggest a relationship to the follow NSR 5, Figure 5-H) of questionable assignment ing species; Eostaffella igoi Niko (this report), to this species were examined. All specimens E. infulaeformis Ganelina, E. oregonensis Sada were obtained from loco A except for UMUT PF and Danner, E. pseudostruvei (Rauzer-Chernou 18033 from loco B. sova and Beljaev), E. toriyamai Ozawa, but E. Description: -Test is moderately large for the kanmerai is recognized by its somewhat irregular genus, involute, and umbilicate on both sides. coiling of volutions and weak chomata. Periphery is rounded to bluntly pointed in axial Igo's holotype (1957, pI. 1, fig. 20) is re section, and lateral slopes are broadly convex. illustrated in this report in order to show its Mature specimens contain 5 1/2 volutions that complete morphology. are 0.32 to 0.37 mm in length and 0.56 to 0.62 mm in width. Form ratio ranges from 0.58 to Eostaffella mosquensis Vissarionova, 1948 0.60. Radius vectors of the first to sixth (5 1/2) Figures 5-D, F, G, H? volutions of the typical specimen (Figure 5-G)

+- Figure 4. A-E, Eostaffella igoi, sp. nov. A, diagonal section of a paratype, UMU~ PF 18022. B, incom plete axial section of the holotype, UMUT PF 18021. C, axial section of a paratype (Immature), UMUT PF 18024. D, axial section of a paratype (immature), UMUT PF 18023. E, sa~ittal se~tion of a paratype, UMUT ~F 18025. F. G, Eostaffella tenebrosa Vissarionova. F, axial (slightly tangential) sec.hon, UMUT PF 18040. G, ax~al section, UMUT PF 18038 .. H-J, Eostaffella kanmerai (lgo). H, diagonal sechon, UMUT P~ 18026. ~, aXial (slightly tangential) section of the holotype, IGUT 20369 (reillustration of Igo, 1957, pI. 1, fig. 20). J, I~complete tangenha. I sec t'iOn, UMUT PF 18027., K Eostafj'l'ellaJ' sp. , axial section, UMUT PF 18041. All specimens X100. 124 Shuji NIKO 834. Eostaffella from the !chinotani Formation 125 are 0.02(?), 0.06,0.10,0.16, 0.25, and 0.32, re pI. 7, fig. 3; Brazhinikova et al., 1967, pI. 21, fig. 7; spectively. The initial 1 to 1 1/2 volutions are Manukalova-Grebeniuk, lI'ina and Serezhikova skew at approximately 40 degrees to the remain 1969, p. 25-26, pI. 6, figs. 9-11; Watanabe, 1973: p. 377-378, pI. 51, figs. 9-14; Ivanova, 1973a, pI. ing essentially planispiral volutions. Proloculus is 2, figs. 5-7, pI. 4, figs. 11-12; Reitlinger, 1973, p. 0.024 to 0.033 mm in inside diameter. Chamber 62, pI. 10, figs. 1-2; Matsusue, 1986, pI. 6, fig. 8. increases in height uniformly throughout the E. postmosquensis postmosquensis Kireeva: Grozdilova growth. Wall consists of a thin tectum, and lower and Lebedeva, 1954, p. 114-115, pI. 14, fig. 9. and upper tectoria; it is 0.010 to 0.014 mm thick E. ex. gr. postmosquensis Kireeva: Ivanova, 1973a, pI. 30, fig. 17. in the final volution. Tunnel is low and narrow except for the ultimate volution which is wider Material studied:-Description is based on two than the penultimate one. Weak, slightly asym axial sections (UMUT PF 18035, sample NS 31, metrical chomata are present in the outer 2 or 3 Figure 3-1; 18037, sample NSR 5, Figure 3-K) volutions, its both (tunnel side and poleward and one slightly diagonal section (UMUT PF side) sides are relatively gentle, occasionally ex 18036, sample NSR 5, Figure 3-1). All specimens tending to poles. were obtained from loco A. Remarks:-This species has considerably wide Description:-Test is small for the genus, variation in the shape of periphery in the outer deeply umbilicate on both sides. Periphery is volutions. However, in the immature stage the rounded in axial section through all growth stage size and skewness of coiling of examined speci of the shell. Lateral slopes are broadly convex. mens are nearly equal. Specimen having Mature specimens contain 4 1/2 volutions that pointed periphery (Figure 5-D) could be classi are 0.17 to 0.22 mm in length and 0.35 to 0.37 fied as Eostaffella mosquensis acuta Rauzer mm in width. Form ratio ranges from 0.50 to Chernousova, but Rozovskaia (1963) has shown 0.59. The initial 1 to 2 volutions are skew to the that E. mosquensis acuta is synonymous with E. remaining essentially planispiral volutions. The mosquensis. Her classification is followed in this last volution is partially evolute. Proloculus is paper. approximately 0.020 mm in inside diameter. Wall This species has been recorded from the in the earlier volutions appears three layered Upper Visean (Alexinsky to Michailovsky hori because of an upper tectorium produced by sec zons) of the Russian Platform and Urals, from ondary deposits on the chamber floors. Chomata the Lower Serpukhovian (C~) of the Donetz are weak and sometimes absent. Tunnel is very Basin, from the Upper Visean (V 3b-V 3C) of West low and narrow. Europe, and from the Upper Chesterian (Zone Remarks:-Eostaffella postmosquensis was 18) of North America. originally described by Kireeva in Rauzer Chernousova et al. (1951) from the Vereisky and Eostaffella cf. postmosquensis Kireeva, 1951 Kashirsky horizons (Lower Moscovian) of the Russian Platform and later this species was Figures 3-I-K identified from the Upper Serpukhovian (Zapal tubinsky horizon) of the Donetz Basin. The Compare:- Kireeva's types generally have much smaller shell Eostaffella postmosquensis Kireeva, 1951, p. 48-49, pI. at corresponding volutions. However, so far as 1, figs. 1-2; Bogush and Iuferev, 1962, p. 178-179, the general shell shape (rounded periphery, deep

+- Figure 5. A-C, E?, Eostaffella subulba, sp. nov. A, tangential section of thc holotype, UMUT PF 18028. B, tangential section of a paratype, UMUT PF 18029. C, oblique section of a paratypc, UMUT PF 18030. E, incomplete diagonal section of questionably assignment to this species, UMUT PF 18031. D, F, G, H?, Eosta[ fella mosquensis Vissarionova. D, axial section, UMUT PF 18033. F, axial section, UMUT PF 18034. G, axial section, UMUT PF 18032. H, sagittal section of questionably assignment to this species, UMUT PF 18070. I, Eostaffella tenebrosa Vissarionova, sagittal (slightly diagonal) section, UMUT PF 18039. All specimens XI00. 126 ShujiNIKO umbilication on both sides) and weaker chomata ness of spirotheca of the last volution of the are concerned examined specimens well agree holotype is approximately 0.015 mm. Asym with the type specimens. metrical chomata are well-developed in the outer This species resembles Eostaffella cooperi volutions. Tunnel is .low and narrow, but in the (Zeller) from the Kinkaid Limestone of Illinois, last volution it becomes wider rapidly than in the but it differs in having smaller proloculus and penultimate volution. Aperture is very low, basal well-developed umbilical depressions. and slit like. The internal morphology of this species Remarks:-Eostaffella subulba somewhat re exemplifies very close relationship to Eostaffella sembles E. hohsienica Chang from the Hochow and Zellerina, but I have assigned the materials Limestone of Anhui Province, China, but this to Eostaffella because they have well-differ new species differs from the latter in having entiated spirotheca. loosely coiled shell, weaker chomata and fewer septa at corresponding volutions. E. endothy Eostaffella subulba Niko, sp. nov. roidea described by Chang (1962) from the Hochow Limestone and E. mosquensis have Figures 5-A-C, E? smaller shell than E. subulba. Material studied:-Holotype, UMUT PF 18028 Unfortunately, it is impossible to determine (sample NS 61, Figure 5-A); paratypes, UMUT the proloculus size and characters of the juvena PF 18029 (sample NSR 6, Figure 5-B), 18030 rium volutions of this form owing to ill-orienta (sample NS 61, Figure 5-C), and a specimen of tion. questionable assignment to this species 18031 (sample NS 10, Figure 5-E) were examined. All Eostaffella tenebrosa Vissarionova specimens were obtained from loco A. Figures 4-F, G, 5-1 Diagnosis.-Large Eostaffella with discoidal to elliptical test, rounded periphery and rapid ex Eostaffella ikensis tenebrosa Vissarionova, 1948, p. pansion of the last volution. Septa short and 220-221, pI. 13, figs. 11-13; Ganelina, 1951, p. straight. Chomata well-developed. 182-183, pI. 1, figs. 2-3; Grozdilova and Lebedeva, 1954, p. 124, pI. 13, fig. 18; Brazhnikova et aZ., Description : -Test is large for the genus, dis 1956, pI. 16, fig. 6; Durkina, 1959, p. 199-200, pI. coidal to elliptical and umbilicate on both sides. 20, figs. 21-22; Rozovskaia, 1963, p. 98, pI. 18, Periphery is rounded in axial section and lateral figs. 1-2; Manukalova-Greboniuk, I1'ina and Serezh slopes are broadly convex. The holotype (Figure nikova, 1969, p. 32-33, pI. 9, figs. 13-14; Mala 5-A) contains at leat 5 volutions that is 0.38 mm khova, 1973, pI. 6, fig. 5; Ivanova, 1973a, pl. 17, fig. 2, pI. 24, figs. 1-3, pI. 30, fig. 14; Sosnina and in length and 0.71 mm in width. Form ratios of Nikitina, 1976, pI. 9, fig. 29. the outer 4 volutions of the holotype are ap Eostaffella cf. ikensis tenebrosa Vissarionova: Chang, proximately 0.53, 0.56, 0.54, and 0.54, respec 1962, p. 437-438, pI. 1, figs. 14-15. tively. A paratype (Figure 5-B) contains at least Eostaffella tenebrosa Vissarionova: Bogush and luferev, 4 volutions is 0.33 mm in length and 0.65 mm in 1962, p. 174, pI. 11, fig. 29. width, giving form ratio 0.51. The largest speci Material studied:-Specimens including two men (Figure 5-C) attains to 0.90 mm in width. axial sections (UMUT PF 18038, sample T2 5, Septa are short and straight except for the last Figure 4-G; 18040, sample NS 40, Figure 4-F), three ones, which are relatively long and faintly three oblique sections, and one sagittal section curved. Septal counts of the last two volutions of (UMUT PF 18039, sample T2 5, Figure 5-1) were a paratype (Figure 5-C) are 14 and 13. Wall studied. All sepcimens were obtained from loco appears three layered because of an upper tecto A. rium produced by the secondary deposits on the Description: -Test is lenticular to rhomboidal chamber floors; in the last volution the wall with arched poles. Outer periphery is pointed in consists of tectum and lower tectorium. Thick- axial section, and lateral slopes are nearly straight 834. Eostaffella from the Ichinotani Formation 127 to slightly concave. Mature specimens contain the last volution, hence this may represent a new 5 1/2 to 6 volutions that are 0.31 to 0.36 mm in species. Test is moderately large for the genus, length, and 0.57 to 0.77 mm in width. Form involute with slightly umbilicate on both sides. ratio ranges from 0.52 to 0.55. In a typical speci Periphery is pointed in the outer three volutions men (Figure 4-F) radius vectors of the second to and more or less rounded in the last volution. six volutions are 0.04,0.08,0.15,0.25, and 0.37 The specimen contains 5 volutions that is 0.33 mm, respectively. Proloculus is approximately mm in length and 0.66 mm in width, giving form 0.021 to 0.025 mm in inside diameter. The initial ratio 0.50. The initial volution is skewed at angle 1 to 1 1/2 volutions are plectogyrally coiled, but of about 48 degrees to the remaining essentially the rest are planispiral. Septa are short, straight planispiral volutions. The last volution inflates and slightly inclined forward. Septal counts of more rapidly than the inner volutions. Proloculus the third to fifth volutions of a specimen (Figure is approximately 0.025 mm in inside diameter. 5-1) are 10, 14, and 16, respectively. Outer pe Wall consists of a tectum, and lower and upper riphery of septal sutures is smooth. Wall is cal tectoria. Low asymmetrical chomta occur in the careous, microgranular and 0.008 to 0.009 mm outer volutions. Tunnel is relatively high and thick in the penultimate volution; it is differ wide in the last volution. entiated into a thin tectum and tectoria. Tunnel is low and narrow in the inner five volutions, but Acknowledgments rather broad in the last volution. Asymmetrical chomata are well-developed through shell except I thank Dr. Y. Okimura of Hiroshima Univer for the juvenarium. Tunnel sides of chomata sity for his valuable suggestions and critically are steep, but poleward slopes are very gentle reviewing the manuscript. This paper is benefited and extending to poles. substantially from the constructive criticism and Remarks:-Eostaffella tenebrosa was original advice of Dr. T. Hamada of The University of ly described by Vissarionova as a variety of E. Tokyo. Dr. H. Igo of The University of Tsukuba ikensis, and was reported from the Michailovsky helped me by supplying type specimen for this (Late Visean) to Steshevsky horizons (Middle study. I would like to thank Dr. K. Sada of Hiro Serpukhovian) of the Donetz Basin, Russian shima University and Dr. K. Ishii of Kobe Univer Platform, Urals, and Sikhote Alin. The Vissario sity for their providing the informaitons. nova's original types have a more pointed periph ery and tightly coiled than examined specimens. References However, it is identical in the general shell shape, and short and straight septa. Adachi, S. (1985): Smaller foraminifers of the Ichino Eostaffella tenebrosa has about the same tani Formation (Carboniferous-Permian), Hida dimensions with E. ikensis and E. enormis. But Massif, central Japan. Sci Rep., Inst. Ceosci., Univ. Tsukuba, Sec. B, vol. 6, p. 59-139, pis. 8- E. ikensis has a more rounded periphery in the 23. outer volutions, and E. enormis has a larger shell Armstrong, A. K. and Mamet, B. L. (1977): Carbon and well-developed chomata. iferous microfacies, microfossils, and corals, Lisburne Group, Arctic Alaska. U.S. Ceol. Survey, Eostaffella sp. Prof Paper 849, 144 p., 39 pis. Bogush, O. l. and Iuferev, O. V. (1962): Foraminifery i Figure 4-K stratigrafiia kamennougol'nykh otlozhenii Karatau i Talasskogo Alatau. Akad. Nsuk SSSR, Sibirskoe Material studied:-Description is based on Otdel., Illst. Ceol. i Ceo[iz., Izdatel, Nauk, Moskva, only one specimen (UMUT PF 18041, sample 234 p., 9 pis. (in Russian). NSR 1) from loco A. Brazhnikova, N. E., Ishchenko, A. M., Ischenko, T. A., Descriptive remarks: - This differs from other Novik, E. O. and Shul'ga, P. L. (1956): Fauna i flora kamennougol'nykh otlozhenii Galitsiisko specimens of the genus in its rapid expansion of Volynskoi Vpadiny. Foraminifery. Akad. Nauk 128 ShujiNIKO

Ukrainskoi SSR, Kiev, Inst. Geol. Nauk Trudy, N. S., no. 123, p. 179-185, pis. 27-29. Ser. strat. i paleollt., vol. 10, p. 16-103, 17 pis. __ , -- and Igo, H. (1984): Foraminiferal bio (in Russian). stratigraphy of the Ichinotani Formation, Hida Chang, Lin-Shin (1962): Fusulinids from the Hochow Massif, cental Japan. IX Int. COllg., Carb. Strat. Limestone, Hohsien, Anhui. A cad. Sinica, Acta Geol., 1979, Compt. Relldu, vol. 2, p. 453-465. Palaeont. Sinica, vol. 10, no. 4, p. 433-441, pI. 1 Ivanova, R. M. (1973a): K stratigrafii sredne- i verk (in Chinese with English summary). nevizeiskikh otlozhenii vostochnogo sklona luzh Durkina, A. V. (1959): Foraminifery nizhnekamen nogo Urala. Akad. Nauk SSSR, Ural'skii Nauchnyi nougol'nykh otlozhenii Timano-Pechorskoi pro Tselltr, Sverdlovsk, Inst. Geol. i Geokhim Trudy, vinsii. Vses. Neft. Nauchno-Issled. Geol.-Razved. vol. 82, Sbor. Voprosam Strat. no. 15, Kamen Inst. (VNIGRI) Trudy, vol. 136, Mikrofauna SSSR, nougol'nye Otlozheniia Vostochnogo Sklona luzh no. 10, p. 132-335, 27 pis. (in Russian). nogo Urala, Marnitgorskii Synklinorii, p. 18-86, Einor, O. L., Kulik, E. L., Popova, Z. G., Reitlinger, E. 34 pis. (in Russian). A., Dunaeva, N. N., Katchanov, E. 1., Alexandrov, --(1973b): Bashkirskii iarus vostochnogo sklona V. A., Solomina, R. V., Zernetzkaya, N. V., luzhnogo Urala. Ibid., p. 87-102, 8 pis. (in Rus Popova, I. V. and Alexandry-Sadova, T. A. (1973): sian). Stratigrafiya i fauna kamennougol'nykh otlozhenii Kato, M. (1959): Some Carboniferous rugose corals reki Shartym (Yuzhy Ural). L'vov, Izdat. 'Vysch from the Ichinotani Formation, Japan. Jour. Fac. cha Shkola', 184 p., 41 pis. (in Russian with Eng Sci, Hokkaido Univ., Ser. 4, vol. 10, p. 263-287, lish summary). 3 pis. Ganelina, R. A. (1951): Eostaffelly i millerelly Viziei Malakhova, N. P. (1972): Foraminifery vizeiskikh skogo i Namurskogo Irusov nizhnego karbona otlozhenii Srednego Urala. Akad. Nauk SSSR, zapadnogokryla podmoskovnoi kotloviny. Vses. Ural'skU Nauchnyi Tsentr, Sverdlovsk, Inst. Geol. Neft. Nauchno-Issled. Geol.-Razved. Inst. (VNIGRI) i Geokhim, Trudy, vol. 101, Sbor. Voprosam Strat. Trudy, vol. 56, Mikrofauna SSSR, no. 6, p. 179- no. 19, Stratigrafiia i Foraminifery Nizhnego 210, 3 pis. (in Russian). Karbona Urala, p. 36-56, 9 pIs. (in Russian). Golubtsov, V. K. (1957): Stratigrafiia i foraminifery Manukalova-Grebeniuk, M. F., I1'ina, M. T. and Serezh Vizeiskogo larusa Pripiatskogo progiba. Akad. nikova, T. D. (1969): Atlas foraminifer; srednego Nauk Belorsskoi SSR. Inst. Geol. Nauk, Minsk, karbona Dneprovsko-Donetskoi vpadiny: Minist. Paleont. i strat. BSSR, no. 2, p. 44-209, 9 pis. Geol. USSR, Ukrainskii Nauchno-Issled. Geol.Inst. (in Russian). (UkrNIGRI) Trudy, vol. 20, 288 p. (in Russian). Grozdilova, L. P. and Lebedeva, N. S. (1954): Foramini Massa. D. and Va chard, D. (1979): Le Carbonifere de fery nizhnego karbona i Bashkirskogo larusa Libye occidentale; Biostratigraphie et micropale srednego karbona Kolvo-Bisherskogo kraia. Vses. ontologie, Position dans Ie domaine tethysien Neft. Nauchno-Issled. Geol.-Razved. Illst. (VNIGRI) d'Afrique du Nord. Inst. Fran(:ais Petrole, Rev., Trudy, vol. 81, Mikrofauna SSSR, no. 7, p. 4-236, vol. 34, no. 1, p. 3-65, 9 pis. 15 pis. (in Russian). Matsusue, K. (1986): Foraminiferal biostratigraphy of Igo, H. (1956): On the Carboniferous and Permian of the lower part of the Akiyoshi limestone Group. the Fukuji district, Hida Massif, with special refer Sci Rep., Dept. Kyushu Univ., vol. 14, no. 4, p. ence to the Fusulinid Zones of the Ichinotani 163-185, 7 pIs. (in Japanese with English abstract). Group. Jour. Geol. Soc. Japan, vol. 62, no. 728, p. Niikawa, I. (1978): Carboniferous and Permian fusulin 217 -240 (in Japanese with English abstract). ids from Fukuji, central Japan. Jour. Fac. Sci., --(1957): Fusulinids of Fukuji, southeastern part of Hokkaido Univ., Ser. 4, vol. 18, no. 4, p. 533-610, the Hida Massif, central Japan. Sci Rep., Tokyo 14 pis. Univ. Education, Sec. C, vol. 5, p. 153-246, 15 --(1980): Geology and biostratigraphy of the Fukuji pIs. district, Gifu Prefecture, central Japan. Jour. Geol. --and Adachi, S. (1981a): Foraminiferal biostrati Soc. Japan, vol. 86, no. 1, p. 25-36 (in Japanese graphy of the Ichinotani Formation (Carbonifer with English abstract). ous-Permian), Hida Massif, central Japan, Part 1 - Niko, S. (1985): Mediocris (primitive fusulinacea) from Some foraminifers from the upper part of the the Ichinotani Formation, Fukuji district, central Lower Member of the Ichinotani Formation -. Japan. Sci Pap., Coll. Art. Sci., Univ. Tokyo, vol. Sci Rep., Inst. Geosci., Univ. Tsukuba, Sec. B, 35, no. 2, p. 165-174, 3 pis. vol. 2, p. 101-118, pIs. 4-6. --(1986): Archaediscidae (smaller foraminifera) of --and -- (1981b): Three species of Lithostrotion the Lower Ichinotani Formation, Fukuji district, from the Ichinotani Formation (Upper Paleozoic Gifu Prefecture and their stratigraphic significance. corals from Fukuji, southeastern part of the Hida Abstracts of Geological Society of Japan, 93rd Massif, part 5). Trans. Proc. Palaeont. Soc. Japan, Annual Meeting at Yamagata, p. 236 (in Japanese). 834. Eostaffella from the Ichinotani Formation 129

Suzuki, M. and Okimura, Y. (1984): On the --(1975): Early Pennsylvanian fusulinacea from the Carboniferous acidic volcanic rocks of the Ichino Omi Limestone in Japan. Mem Fac. Integr. Arts tani Formation, Fukuji district, Hida marginal and Sci, Hiroshima Univ., vol. 1, p. 31-39, pI. 1. zone. Abstracts of Geological Society of Japan, --(1980): Primitive fusulinacea from the Nakamura 91st Annual Meeting at Tokyo, p. 226 (in Japa Limestone in Western Japan. Jour. Paleont., vol. nese). 54, no. 1, p. 65-70, pI. 1. Ozawa, T. (1976): Late Visean Eostaffella (Fusulinian --and Danner, W. R. (1973): Late Lower Carbon foraminifera) from West Malaysia, Contributions iferous Eostaffella and Hexaphyllia from central to the geology and palaeontology of Southeast Oregon, U.S.A. Trans. Proc. Palaeont. Soc. Japan, Asia, CLXXI. Geology and Palaeontology of South N. S., no. 91, p. 151-160, pis. 23-24. east Asia, vol. 17, p. 117-128, pis. 22-24, Univer --and -- (1974): Early and Middle Pennsylvanian sity of Tokyo Press, Tokyo. fusulinids from southern British Columbia, Canada Rauzer-Chernousova, D. M. (1948): Nekotorye novye and northwestern Washington, U.S.A. Ibid., no. 93, vidi foraminifer iz nizhnekamennougol'nykh otlo p. 249-265, pis. 35-37. zhenii Podmoskovnogo basseina. Akad. Nauk --, Nomura, K. and Oho, Y. (1984): Primitive fusuli SSSR, Inst. Geol. Nauk Trudy, vol. 62, Geol. Ser., nacea from Dangyokei of Taishaku (Studies of the no. 19, p. 227-238, pis. 15-16 (in Russian). stratigraphy and the microfossil faunas of the -, Beljaev, G. M. and Reitlinger, E. A. (1936): Carboniferous and Permian Taishaku Limestone in Verkne-paleozoiskie foraminifery Pechorskogo West Japan, no. 5). Ibid., no. 134, p. 388-392, kraia. Akad. Nauk SSSR, Poliarnoi Komissii pI. 75. Trudy, vol. 28, p. 159-232,6 pis. (in Russian with Sakagami, S. (1960): Nipponostenopora, a new Carbon German summary). iferous bryozoan genus from Fukuji, Hida Massif, --, Gryzlova, N. D., Kireeva, G. D., Leontovich, G. Japan. Japan Jour. Geol. Geogr., vol. 31, p. 9-11, E., Safonova, T. and Chern ova, E. I. (1951): pI. 2. Srednekamennougol'nye fuzulinidy Russkoi plat Sosnina, M. I. and Nikitina, A. P. (1976): Kamen formy i sopredel'nykh oblastei. Akad. Nauk SSSR, nougol'nye foraminifery Primorya. Vses. Nanchno Moskva, Inst. Geol. Nauk, Minist. Neft. Promyshlen Issled. Geol.Inst. (VSEGEl) Trudy, N. S., vol. 247, nosti SSSR, 380 p., 58 pis. (in Russian). 112 p., 16 pis. (in Russian). Rich, M. (1980): Carboniferous calcareous foraminifera Tazawa, 1. and Kato, M. (1986): Striatifera and Giganto from northeastern Alabama, south-central Ten productus from the Lower Carboniferous of nessee, and northwestern Georgia. Cushman Fukuji, central Japan. Trans. Proc. Palaeont. Soc. Found. Foraminiferal Research, Spec. Publ., no. 18, Japan, N. S., no. 142, p. 393-399, pI. 78. 62 p., 22 pis. Vachard, D. (1977): Etude stratigraphique et micro Rozovskaia, S. E. (1963): Dreveishie predstaviteli paleontologique (algues et foraminiferes) du Viseen fuzulinid i ikh predki. Akad. Nauk SSSR, Pale de la Montagne Noire (Herault, France). Louvain ontol.Inst. Trudy, vol. 97, 128 p., 22 pis. (in Rus Univ.Inst. Geol. Mem, vol. 29, p. 111-195,8 pis. sian). Vissarionova, A. la. (1948): Primitivnye fuzulinidy iz Sada, K. (1964): Carboniferous and Lower Permian nizhnego karbona Evropeiskoi chasti SSSR. Akad. fusulines of the Atetsu Limestone in West Japan. Nauk. SSSR, Inst. Geol. Nauk Trudy, vol. 62, Jour. Sci, Hiroshima Univ., Ser. C, vol. 4, no. 3, Geol. SeI., no. 19, p. 216-226, pis. 13-14 (in p. 225-269, pis. 21-28. Russian). --(1967): Fusulinids of the Millerella zone of the Watanabe, K. (1973): Profusulinella assemblage in the Taishaku Limestone (Studies of the stratigraphy Omi Limestone, Niigata Prefecture, central Japan and the microfossil faunas of the Carboniferous (Studies of Carboniferous Fusuliancean of Omi, and Permian Taishaku Limestone in West Japan, part 1). Trans. Proc. Palaeont. Soc. Japan, N. S., no. 1). Trans. Proc. Palaeont. Soc. Japan, N. S., no. 92, p. 371-394, pis. 51-53. no. 67, p. 139-147, pis. 12-13. Wu, Wang-Shi, Chang, Linn-Shin and Ching, Yii-Kan --(1969): Microfossils of the lowest part of the (1974): The carboniferous rocks of western Kuei Taishaku Limestone (Ibid., no. 4). Ibid., no. 75, p. chow. Mem. Najking Inst. Geol. Paleollt., A cad. 119-129, pis. 12-13. Sinica, no. 6, p. 72-87, 8 pis. (in Chinese). 130 ShujiNIKO

Ichinotani -/~. Fukuji :ffiitl!!. Mizuboradani 7j(11".1~. Mizuyagadani *~..,.~. Hochow 5!'llj·I'i. Anhui *~.

:ffiitl!!:l1!!~- / ~~iI' ~ 0)15 .l!R*ciliIWl Eostaffella CW-~{jEt:J 7 ?:' !J j-JD : i!lt.$.JJi!, tr:!~UIL1:~t-.t:ffii tl!!tI!!~O)- / ~~r$iI' ~ It~&tJ:1HL~11::15~>a:-~I±li' ~ • .!fIB]. 3 ~~ CEostaffella excavata. E. igoi. E. subulba) >a:-~t; 8 ~0)W-~{jEt:J7?:'!J j-J{ CEostaffella) ">a:-~~ff:~Et:J5t* O)t.:l5bO)£~Et:JT·-.? C l- -c~tn.. t.:. :::. 0)7;(!J j-11::15~lt. igo (1956) ~.::. J: ~ Eostaffella kanmerai zone ~'::'~l5b ~:h. :to)~fI;;lt ~ -It 7 /J1i\:~Wlil'~~}!.-7·- ~ * - ~'7 /iliIWl-C-;!;~ C ~~~:h~. ~~.~ Trans. Proc. Palaeont. Soc. Japan, N. S., No. 147, pp. 131-145,5 Figs., October 30,1987

835. ON THE SILURIAN TRILOBITE FAUNULE OF HITOEGANE NEAR FUKUJI IN THE HIDA PLATEAU, JAPAN*

TEIICHI KOBAY Asm The Japan Academj, Ueno Park, Tokyo

and TAKASm HAMADA Department of Earth Science and Astronomy, College of Arts and Science, University of Tokyo

Abstract. A new collection from Hitoegane adjacently north of Fukuji, Gifu Prefecture contains more than nine species of trilobites in the Scutelluidae, Illaenidae (?), Proetidae, Cheiruridae and Encrinuridae, including four new species, namely Kbsovopeltis hidensis, Proetus (Coniproetus) tenuiceps, P. (Coniproetus?) subconicus and Cheirurus hitoeganensis. This faunule is late or middle Ludlovian in age and shows affinities to the East Australian fauna through the Yokokura-yama, Shikoku and the Bohemian fauna through the trilobites of the Mongolian geosyncline. Encrinurus cf. similis found at Hakubado, Fukui Prefecture is about the same age.

The Favosites fauna of Ichinotani at Fukuji, cf. similis. Hitoegane and Hakubado are two Kamitakara Village, Y oshiki County, Gifu Pre Silurian fossil localities in the Hida plateau which fecture which has once been considered Silurian are located respectively in the eastern and west (Kamei, 1949) was later transferred to the ern parts of the plateau with a distance of about Devonian (Kobayashi and Igo, 1956) and still 90 km between them. The geology of these lo later the Fukuji Formation was determined to be calities are so highly complicated that the rela within the range from Gedinnian to Eifelian tion of these Silurian rocks to the older and (Igo et al., 1975; Kobayashi and Hamada, 1977; younger Paleozoic formations is not yet clari Igo and Adachi, 1981). Prior to this a few pyg fied. idia were found in limestone boulders at Hitoe A new trilobite collection of Hitoegane con gane hill about 1500 m to the north-northeast tained mostly in limestones, but Encrinurus cf. of Fukuji. They were found to be a new species kitakamiensis whose mother rock is green tuffa of Encrinurus as denominated Encrinurus ceous shale casts a question on the age of Scutel fimbriatus by the authors (1974). Thus the lum (?) sp. indet. The authors reported it as a Silurian limestone was proven to exist at Hitoe Silurian trilobite (1965), but later a Devonian gane in the Fukuji area. one (I 977). Now it becomes more probably a Ohno, Okazaki and Hirano (1977) on the Silurina trilobite in looking the similarity of its other hand discovered Encrinurus at Hakubado, mother rock with that of Encrinurus cf. kita Izumi Village, Ohno County, Fukui Prefecture. kamiensis. As the result of restudy on this speci The authors are of opinion that it is Encrinurus men it is called here Decoroscutellum (?) sp. indet. *Received November 7, 1986; Studies on Japanese The Hitoegane trilobites in the new collec Trirobites and Associated Fossils-IL. tion are the following forms in the Scutel-

131 132 Teiichi KOBA YASHI and Takashi HAMADA

luidae, Illaenidae (?), Proetidae, Cheiruridae and was primarily founded on some pygidia from Encrinuridae. Hitoegane. The new collection contains not only Kosovopeltis hidensis, sp. nov. pygidia but also cranidia. This species is allied Kosovopeltis hidensis f. striatus, fonna. nov. to not only E. subtrigonalis and E. yokokurensis Illaenid (?) gen. et. sp. indet. from Mt. Yokokura in Japan but also E. sinicus Proetus (Coniproetus) tenuiceps, sp. nov. Kuo from near Kirin, Northeast China (Kuo, Proetus (Coniproetus?) subconicus, sp. nov. 1962). Judging from these facts the Hitoegane Cheirurus hitoeganensis, sp. nov. limestone faunule is Ludlovian and probably Cheirurid, gen. et sp. indet. (Hypostoma) middle or late Ludlovian in age. Sphaerexochus sp. indet. Thus there are three trilobite horizons in the Encrinurus fimbriatus Kobayashi and Hamada Hitoegane area. The tuffaceous shale containing Encrinurus cf. kitakamiensis Sugiyama Encrinurus cf. kitakamiensis is probably upper All of these trilobites are contained in lime Ludlovian. Judging from the lithological simi stone except for Encrinurus cf. kitakamiensis. larity the Decoroscutellum (?) bearing schalstein In the Kitakami mountains, North Japan E. kita may be about the same age. The trilobite faunule kamiensis horizon lies immediately above the in the limestone of Hitoegane is judged to be middle Ludlovian limestone containing Schedo lower-middle Ludolovian. The Hitoegane trilo halysites kitakamiensi$ (Hamada, 1961). There bites as a whole suggest the faunal connection to fore the superadjacent trilobite horizon must be the fauna of eastern Australia through the Yoko late Ludlovian, if not Pridolian in age. Decoro kura-yama fauna on one side and on the other scutellum as a genus ranges from Wenlockian side to the Central European fauna through the to Lower Devonian, although it thrived in the Urals. This biogeographic suggestion is in support Ludlovian. The generic reference of the pygidium of the trilobite pygidia from Hakubado, as they in question is provisional. Therefore the exact look very similar to Encrinurus similis from age of Decoroscutellum (?) sp. indet. in schal Gomi quarry on Mt. Yokokura. stein is indeterminable. Among the trilobites in the limestone of Description of trilobites of Hitoegane there is none spcifically identifiable the Hitoegane Faunule with any species from Yokokura-yama or other locality in Japan. Kosovopeltis, Proetus, Sphaer Beside some known species and indetennin exochus and Encrinurus are common genera able fonns four new dpecies are here included as between the Hitoegane and Yokokura-yama follows: faunas, but Proetus (Coniproetus) is unknown Kosovopeltis hidensis, sp. nov. from Yokokura-yama.Kosovopeltis Snajdr, 1958 Kosovopeltis hidensis fonna striatus, fonna is a Silurian scutelluid genus flourished in the nov. Ludlovian (Kopanina to Lochkov beds) in Proetus (Coniproetus) tenuiceps, sp. nov. Bohemia (Emsian) and a species is known from Proetus (Coniproetus?) subconicus, sp. nov. the Urals (Snajdr, 1960). Among the Japanese Cheirurus hitoeganensis, sp. nov. trilobites K. hidensis is allied to K. angusti The hypostoma is known of Encrinurus costatus of the Yokokura-yama fauna. Proetus fimbriatus. On this occasion Encrinurus cf. (Coniproetus) as a genus is distributed in Europe similis from Hakubado is also described. Some and North Africa in the range from Silurian notes are supplemented on the Genus Proetus, (lower Budnanian) to Devonian (Emsian) Subgenus Proetus (Coniproetus) and Genus (Alberti, 1969). Cheirurus hitoeganensis is close Encrinurus. ly allied to Cheirurus insignis Beyrich from the upper Wenlockian (Liten high) in Bohemia (Horny and Bastl, 1970). Encrinurus fimbriatus 835. Silurian Trilobites of Hida 133

Family Scutelluidae R. and E. Richter, 1955 perfect, its outline may be semi-elliptical. It Genus Kosovopeltis Snajdr, 1945 agrees with the above cranidium in the low con vexity and the mode of striation on the axial Kosovopeltis hidensis Kobayashi and Hamada, lobe. Its obsolete trilobation is very distinctive sp. nov. among scutelluids. It is somewhat similar to Figures I-Ia-c, 2, 3-7 Kosovopeltis angusticostatus from Mt. Yoko kura, but the ribs are narrower than furrows and Description:-Cranidium broad and gently in ornamented with fine crenulation. flated. Glabella expanded in anterior more than In Kosovopeltis nebula Campbell, 1967 from twice its breadth in posterior, somewhat con Oklahoma the trilobation of the axial lobe is tracted at posterior lateral furrows and slightly obsolete in anterior, but a pair of longitudinal depressed behind frontal rim; anterior and furrows are distinct in posteiror. middle lateral furrows transversal, disconnected Finally, Bronteus partschi Barrande by Weber, from lateral margin and the latter half as wide as 1951 in fig. 13, pI. 2 is a similar pygidium in the former; posterior lateral furrow shown by obsolete trilobation of the axial lobe and in roundly sub quadrate depression incised from fine crenulation of the ribs and the pleural lateral margin; median smooth zone as wide as furrows stronger in the Kazakhstan form. The posterior lateral furrow; middle lateral lobe nar pygidium is probably longer and the axial lobe row (sag.); anterior lateral lobe a little wider relatively smaller in that species. than two others; occipital furrow transversal; Occurrence:-Limestone, Hitoegane. An im neck ring narrowing laterally; its posterior perfect thoracic segment having lirae like the margin arcuate; axial furrow deep. Fixed cheek cephalon is contained in the collection. depressed, moderate i~ breadth; eyes large, opposed at posterior lateral furrows and ex Kosovopteris hidensis forma striatum panded postero-Iaterally; eye-ridge present; alae Kobayashi and Hamada, forma nov. small, semicircular, opposed at galbellar constric tion. Frontal rim separated from glabella by nar Figure 1-3 row furrow, broadly arcuate, distinctly elevated This cranidium agrees best with Kosovopeltis and extending beyond eyes; frontal marginal hidensis in most aspects, but the test is more furrow becoming deeper on lateral sides; anterior strongly striated and the striation becomes very facial sutures widely divergent from eyes, but irregular in posterior. The frontal marginal bent back at marginal rim. Doublure vertical. furrow is rudimentary, the anterior outline more Very fine transversal striae densely distributed convex forward and the middle lateral furrow nearly whole cranidium. indicated by a very small but deep pit. The fixed Observation:-An associated pygidium is near cheek is much more convex in this form, if com ly flat except for the axial lobe whose outline pared with the preceding. is triangular and a little elevated above the level Occurrence:-Limestone, Hitoegane. of the pleural field. This lobe is simply flat topped, non-trilobate and decorated with fine Genus Decoroscutellum Snajdr, 1958 transversal striae. The axial furrow is nearly straight and shallow but fairly wide. The post Decoroscutellum (?) sp. indet. axial rib is somewhat broadened in posterior. 1965. Scutellum (?) sp. indet. Kobayashi and Hamada, Seven pleural ribs on its lateral side look more Trans. Proc. Pal. Soc. Japan, N. S., no. 58, p. 78, or less convex antero-Iaterally. All of these ribs pI. 7, figs. 4a-b, text-fig. 2 are crossed by sharp ridges on the top. The 1977. Scutellum (?) sp. indet. Kobayashi and Hamada, pleural furrows are narrow and profound. Palaeont. Soc. Japan, Spec. Pap., no. 20, p. 80, Comparison: - Though the pygidium is im- pI. 1, figs. 4a-b. 134 Teiichi KOBA YASHf and Takashi HAMADA 835. Silurian Trilobites of Hida 135

An imperfect pygidium of a scutelluid whose Occurrence:-The specimen is contained in anterior margin is broad and straight. Its trian schalstein of Hitoegane. It was once considered gular axial lobe is trilobate and the median lobe a Devonian Scutellum, but its age would be late swelling upward in posterior, possibly forming a Silurian, judging from the otter Hitoegane trilo median tubercle. The post-axial median rib is bites. much broader than lateral ribs in anterior, some what narrowing back and then broadened back Family Proetidae Salter, 1864 ward. Whether it is bifurcate or not is indeter Subfamily Proetinae Salter, 1864 minable. Among seven pairs of lateral ribs the second and third ones are distinctly bent with Genus Proetus Steininger, 1831 convexity on the antero-lateral side. The fourth As stated already in 1977 (pp. 132,180), the and sixth ribs are somewhat arcuate toward the classification of the Proetidae and Proetacea is a opposite side in the distal half. Thus the lateral subject of most discussion. Many questions are ribs are more or less sigmoidal. All ribs are flat also attached to the subgeneric division of genus and separated from one another by much nar Proetus. Proetus (Coniproetus) is, however, ac rower furrows. The lateral posterior margins are ceptable as a good subgenus, although a question unknown, but it is known that the doublure ex still remains as to the synonymy of Bohemi tends about an outer half of the pleural field. proetus with Coniproetus. The pygidium is presumably subpentagonal in outline. In the distinct trilobation of the axial Subgenus Coniproetus Alberti, 1966 lobe, the posterior tubercle (?) of its median lobe and the more or less sigmoidal pleural ribs, this Diagnosis:-Glabella coniform; lateral glabellar pygidium agrees with Decoroscutellum (Decoro furrows not incised; short (sag.) preglabellar field scutellum) haidingeri (Barrande) from the commonly developed; lateral occipital lobes well Kopanina beds in figs. 1-3, pI. 6 in Snajdr defined; eye platform typically absent; long genal (1960). In this pygidium, however, the pleural spines in most species; pygidial border well furrows are considerably narrower than in developed; band of parallel terrace lines around Barrande's species. The furrows are, however, pygidial margin; exoskeleton smooth, or with very narrow in D. (Decoroscutellum) lepidum granular sculpture. lepidum BoU(~ek) from the Lochkov beds in fig. Type-species:-Proetus glandiferus Novak, 4, pI. 7, Snajdr (1960). The median rib is well 1890 bifurcate in Bou~ek's species, whereas the Remarks: -This subgenus was primarily bifurcation occurs only in the terminal part in founded on Proetus condensus Pfibyl, 1965. Ac Barrande's species. Thus it is probable that this cording to Owens (1973), however, its type pygidium belongs to an unknown species of species must be Proetus gladiferus Novak, 1890, Decoroscutellum. because both of them belong to an identical

~ Figures l-la-c, 2. Kosovopeltis hidensis Kobayashi and Hamada, sp. nov. A dorsal (a), frontal (b) and right lateral (c) views of the holotype cranidum. x4.2, PA 18095.2. A dorsal view of an incomplete pygidum. x1.6, PA 18096. 3. Kosovopeltis hidensis forma striatum Kobayashi and Hamada, forma nov. A dorsal view of an incom plete cranidium. xL 7, PA 18097. 4a-d. Proetus (Coniproetus) tenuiceps Kobayashi and Hamada, sp. nov. A dorsal (a), left lateral (b), frontal (c) and posterior (d) views of the holotype cranidium. x5.3, PA 18098. (Vide Figures 2-la, b also). Sa-d. Proetus (Coniproetus?) subconicus Kobayashi and Hamada, sp. nov. Dorsal (a, b), left lateral (c) and frontal (d) views of an incomplete cranidium. a: x8.2, b, c, d: x7.1, PA 18099. 6a, b. Illaenid (?) gen. et sp. indet. A dorsal (a) and posterior (b) views of an ill-preserved pygidium show ing the slanting margin which is covered by striation on the undersurface of doublure. x3.7, PA 18113. 136 Teiichi KOBA YASHI and Takashi HAMADA species. Furthermore Proetus (Bohemiproetus) frontal and dorsal furrows; facial sutures slight Pillet, 1969 is synonymous with Proetus (Coni ly divergent from eyes as far as parallels through proetus) because Proetus bohemicus Hawle and lateral eye-limits and then curved inward; test Corda, the type-species of the former, is not so smooth. different from P. glandiferus as they can be sepa Observation: -The median tubercle is seen on rated subgenerically. Thus the above quoted diag the exfoliate part of the test. The occipital lobes nosis was given by Owens. are indicated by short oblique notches from the Distribution:-According to Alberti (1969) occipital furrow into the occipital ring. The this subgenus is distributed from Silurian (lower dorsal furrow is separated from the narrow fron Budnanian) to Devonian (Emsian) in Europe tal marginal furrow by a space i.e. the preglabel Africa. As noted by the authors (1974, 1977), its lar field, narrower than these furrows. Some par trans-Eurasiatic distribution through the Mongo allel striae are seen on the frontal border. lian geosyncline is shown by the occurrences of Comparison : -This species can be distin Proetus bohemicus in the Lower Devonian of guished from not only Proetus (Coniproetus) Turkestan (Weber, 1932) as well as Proetus glandiferus Novak, but also the Devonian species (Coniproetus) fukujiensis from the Lower-Middle from North Africa (Alberti, 1969) and the Devonian of Fukuji, Japan. Preoetus (Coni Armorican massif, France (Pillet, 1972) in the proetus) subconicus here described proves fur longiconic glabella. In the general aspect of the ther that such an extensive distribution of the cranidium it resembles Proetus (Longiproetus) subgenus was started already in the late Silurian pseudotenuis (Pillet), an Armorican species close age. ly, but the median tubercles absent on the neck ring and the marginal border is flat or concave Proetus (Coniproetus) tenuiceps in Proetus (Longiproetus). Ludlovian Proetus Kobayashi and Hamada, sp. nov. obconicus Lindstrom which Owens (1973) referred to Proetus (Lacunoproetus) Yolkin, Figures 1-4a-d, 3-1a-b 1966 and also Wenlockian P. (L.) confusus Description:-Glabella longiconic, well con Owens, 1973 have the cranidium and glabella vex, almost straight laterally and abruptly round similar to this species in outline and convexity, ed in front; lateral furrows obsolete; occipital but the lateral furrows are completely effaced on furrow profound and transversal; occipital ring the glabella and the eyes larger and located more very short sagittaly, well arcuate on posterior posteriorly in this species. Proetus (Bohemicus) side, depressed below glabella, provided with a magnicervicu/us from Mt. Yokokura agrees with median tubercle and a pair of small lateral lobes this species nicely, but the glabellar outline is indicated by a pair of notches; palpebral lobe quite different. Judging the essential character fairly long and located far posteiorly; fixed istics of the cranidium this form is considered cheek narrow; frontal border convex, well devel best to place in Proetus (Coniproetus). oped, separated from glabella by marginal fur Occurrence:-Limestone, Hitoegane. row; preglabellar field almost nullified between

~ Figures 2-1a, b. Sphaerexochus sp. indet. A dorsal (a) and right lateral (b) views of an ill-preserved cranidium showing a distinct basal lobe and a neck ring. xl.8, PA 18103. 2a, b. Cheirurid, gen. et sp. indet. (hypostome). A ventral (a) and left lateral (b) views of an incomplete hypostoma showing the general outline. xl.9, PA 18102. . 3a-c. Cheirurus hitoeganensis Kobayashi and Hamada, sp. nov. A dorsal (a), left lateral (b) and posterior (c) views of an incomplete pygidum. x3.4, PA 181Ol. 4a-c,5a-d. Encrinurus fimbriatus Kobayashi and Hamada, 1974. A dorsal (a), frontal (b) and left lateral (c) views of a cranidium showing hte general outline with rounded genal angle. xl.8, PA 18104. 5a-d. Another specimen of cranidum. xl.7, PA 18105. 835. Silurian Trilobites of Hida 137

1 a 1 b 138 Teiich; KOBA YASHI and Takashi HAMADA

Proetus (Coniproetus?) subconicus Cheirurus hitoeganensis Kobayashi and Hamada, Kobayashi and Hamada, sp. nov. sp. nov. Figures 1-5a-d Figures 2-3a-c

Description: -Cranidium nearly as long as Description:-Pygidium exclusive of spines broad and moderately inflated. Glabella conical, sub triangular; axial lobe composed of three rings rounded in front, gently rising toward its center; and a terminal piece; pleural part of anterior two occipital ring well developed and provided with segments divided into two short ridges by diago a pair of lateral lobes; occipital and dorsal fur nal interpleural furrow for a short distance till rows profound. Fixed cheek narrow; palpebral lateral spine issues; third segment also bisected lobe large, semicircular, provided with narrow but into narrower ridges; three pairs of equally eye-band and opposed in posterior of glabella. long spines extending laterally and posteriorly Frontal border well convex, thick and separated with convexity on antero-Iateral side; terminal from glabella by narrow marginal furrow; ante pieces ill-developed; posterior margin between rior fIxed cheek expanded laterally, as long as third spines simply convex backward. Test ap frontal border and divided into two parts by a parently smooth. weak crest. Facial sutures running forward di Comparison: -This pygidium best agrees with agonally from two sides of eyes. Test smooth. Cheirurus insignis Beyrich, but the terminal piece Observation and Comparison:-An imperfect of the axial lobe is ill-defIned and the posterior cheek having a low crest parallel to the cheek margin not produced as in C. insignis. Didero margin and distinct depression along its inner panon has three pairs of lateral spines on the side belongs probably to this species. The cepha pygidium, but only the anterior two pairs are Ion of this species resembles Proetus (Coni elongated. In Cheirurus on the other hand has proetus) tenuiceps in the conical glabella and three pairs of spines all long like in this species. absence of the preglabellar fIeld, although the The axial lobe consists of three rings and a ter glabellar outline tapers more slowly and broadly minal piece which the last is protruded behind rounded in front in that species. The low crest in the typical species of Cheirurus. The pygidium on the cheek is the most important distinction of Contracheirurus errator Lane, 1984 is similar from Proetlls (Coniproetus). to this pygidium in possession of three pairs of Occurrence:-Limestone; Hitoegane. long lateral spines and the entire post-axial margin. The terminal piece of the axial lobe is, Family Cheiruridae, Salter, 1864 however, clearly defined and the lateral spines Genus Cheirurus Beyrich, 1845 become shorter posteriorly in that species.

~ Figures 3-1a, b. Proetus (Coniproetus) tenuiceps Kobayashi and Hamada, sp. nov. A dorsal (a) and lateral (b) views of an incomplete free cheek. x6.0, PA 18098. 2a-c, 3a-e, 4a-d. Encrinunls fimbriatus Kobayashi and Hamada, 1974. 2a-c. A dorsal (a), right lateral (b) and posterior (c) views of a large pygidium. xl.9, PA 18106. 3a-c. A dorsal (a), posterior (b) and right lateral views of another pygidium. x2.1, PA 18107. 4a-d. A dorsal (a), posterior (b), right (c) and left lateral views of another small pygidium. x2.1, PA 18108. 5. Trilobita, gen. et sp. indet. A fragmentary free cheek showing a long genal spine and the surface tuber culation. x3.6, PA 18114. 6. Encrinurns cf. kitakamiensis Sugiyama, 1941. A dorsal view of somewhat flattened pygidum preserved in shale. x3.1, PA 1811!. 7. Kosovopeltis hidensis Kobayashi and Hamada? A dorsal view of a fragmentary thoracic segment. x!.9, PA 18115. Sa-d. Encrinurus cf. similis Kobayashi and Hamada, 1974. A dorsal (a), left lateral (b) and posterior (c) views of an imperfect pygidum (a latex replica) obtained from a small exposure nearby the Hakubado, Fukui Prefecture. x2.1, PA 18112. 835. Silurian Trilobites of Hida 139 140 Teiichi KOBA YASHI and Takashi HAMADA

Occu"ence:-Limestone; Hitoegane. Occu"ence: -Limestone, Hitoegane.

Cheirurid, gen. et sp. indet., Hypostoma Family Encrinuridae Angelin, 1854 Figures 2-2a-b Genus Encrinurus Emmerich, 1844

A fairly large hypostoma, much longer than Encrinurus is well represented in Japan by broad, well rounded and auriculate in anterior; various pygidia from many localities among lateral margins gradually tapering back behind which ten species can be distinguished with small anterior wings and truncated by trans reference to the segmentation, relative breadth versal posterior margin; main body long, oval and of the axial lobe, presence or absence of the separated from posteior part by deep, short and smooth median band or/and median tubercles oblique depressions on lateral parts; lateral bor on the lobe and so forth. Cephala are not so com der moderate in breadth and depressed. Test with mon, but three kinds were found in Mt. Yoko fine granules. kura collection. Because they are detached, This hypostoma measures 17 mm in length their combination is inevitably a play of pre and 8.6 mm in breadth. It is not so well pre sumption. served that its outline is traceable exactly. Its Hitoegane collection contains not only two general aspect, however, suggests its reference to pygidia but also a cephalon of Encrinurus fim the Cheiruridae (Prantl and Ptibyl, 1947, Lane, briatus all in the same kind of limestone, beside 1971, Ramsk6ld, 1982). It looks similar to the a pygidium of Encrinurus aff. kitakamiensis in a hypostoma of Cheirurus insignis Beyrich, 1840. shaly rock. Encrinurus cf. similis occurs at Haku Compared to the cranidium and pygidium it is bado in limestone. considerably larger. Its reference to that species is hesitated by its coarse granulation. Encrinurus /imbriatus Kobayashi and Hamada, Occurrence:-Limestone, Hitoegane. 1974 Figures 2-4a-c, 5a-d, 3-2a-c, 3a-c, 4a-d, Subfamily Sphaerexochinae Oepik, 1937 4-1a-e, 2a-e, 5. Genus Sphaerexochus Beyrich, 1985 1974. Encrinurus fimbriatus Kobayashi and Hamada, Sphaerexochus sp. indet. Pal. Soc. Japan, Spec. Pap., no. 18, p. 107, pI. 11, Figures 2-1a-b figs. 10-11, text-fig. 7H.

An imperfect cranidium of Sphaerexochus This species was primarily founded on pygidia whose occipital and pre-occipital furrows are very which are sub triangular, but its anterior margin broad and fairly deep. They are confluent to is well arcuate near lateral extremities, and each other to isolate the basal lobe. The two strongly convex, arching down on the lateral and other lateral furrows are unpreserved or com posterior sides, but the adaxial pleural part is pletely effaced in front of the pre-occipital fur nearly flat; axial lobe narrow, long, conical, regu row. The basal lobe of moderate size looks larly tapering back, gently convex, a little ele roundly subquadrate. The cheeks and all other vated above the pleural lobes and abruptly bent parts are unknown. Therefore its comparison down near posterior end, terminating at blunt with Sphaerexochus hiratai or any other species end inside the posterior margin for a short dis cannot be made. tance, and divided into numerous rings. Pleural

~ Figures 4-1a-e, 2a-e. Encrinurus fimbriatus Kobayashi and Hamada, 1974. Two casts of hypostom at a showing the general outline and the rough musclature. 1a-e, x5.0, PA 18109, 18110. This specimen was found in association with a pygidium of Encrinurus fimbriatus that is shown in Figures 3-4a-d, 2a-e, x5.7, PA 18108. 835. Silurian Trilobites of Hida 141

1 e 142 Teiichi KOBA YASHI and Takashi HAMADA lobes are divided into 10 to 11 ribs by profound convex are considered to belong probably to this pleural furrows, the most anterior one of which species. The glabella is well inflated, arching is very narrow. down in anterior and densely tuberculate. Five The axial lobe is about one-fourth as wide as pairs of tubercles are aligned along the lateral the pygidium. Some 20 axial rings are countable margins, middle three of which are more promi on its main part. In adding incountable posterior nent than two others; smaller tubercles irregular ones on the terminal bent part, they probably ly distributed in the inner part. The occipital attain 30 in total. The median smooth band is margin is unpreserved. Axial furrows are well absent, but some rings are depressed mesially. developed. Cheeks are largely destroyed. The Median tubercles are very sparse. The pleural ribs right cheek is a little displaced from the glabella are somewhat expanded at their lateral termini. in a cranidium in Figure 5. The eye-scar of The new collection contains four pygidia. moderate size is seen on its posterior part. The A small one which is better preserved than the genal angle is rounded; genal spine absent. others shows the mode of segmentation clearly. Among the three kinds of Encrinurus-cephala The details of the axial rings, pleural ribs and so far known from Japan it is most similar to E. furrows are better shown in this than the holo yokokurensis from which, however, it differs in type pygidium. The small specimen in Figures the mode of tuberculation. It agrees better with 24a-c is 15 mm long, 14 mm wide, and 5.3 mm Encrinurus sinicus, from Northeast China in high and its axial lobe is 5 mm wide at the ante possession of five pairs of tubercles on the rior end. The respective dimensions are 21.7 mm, glabella along axial furrows, middle three of 17.3 mm, 9 mm and 8.3 mm in a large pygidium. which are more developed than two others. In The proportional differences between the two this species two rows of tubercles counted from pygidia chiefly depend upon the convexity. The the posterior side are composed of four tubercles former pygidium is compressed laterally, whereas as in E. sinicus. The tuberculation in further the latter is depressed longitudinally so much anterior is complicate and their arrangement that the posterior bent becomes vertical. disagrees with E. sinicus. In that species the This species resembles Encrinurus sub trigo occipital lobe is much wider than the glabellar naZis and E. similis in the subtriangular outline base. Of E. sinicus it is said that "genal angles and strong convexity of the pygidium. These incomplete apparently terminating in spines." Yokokura-yama pygidia, however, have much This cephalon resembles alos Encrinurus broader axial lobes and pleural ribs in smaller kongshaensis Reed, 1906, from Burma, but "the number. They are 9 to 10 in this species but 7 to fifth (basal) pair (of tubercles) is smaller and its 8 in that species. The tuberculation is well devel members are connected together by a weak ridge oped on the pleural ribs, particularly in Encrinu across the glabella." This aspect is quite distinc rus subtrigonaZis, but the ribs are non-tuberculate tive for this Burmese species from this species, in this species. other Japanese species and also E. sinicus. Encrinurus sinicus Kuo, 1960, from North Hypostoma of Encrinurus /imbriatus: The east China has 25 axial rings some of which bear hypostoma of this species is rhomboidal, a little median tubercles. His fig. 5, pI. 1 and fig. 7, pI. 2 longer than broad and more or less protruded show that the axial rings are interrupted by a laterally as well as posteriorly. The central body median smooth band. Pleural ribs are said eight is suboval, but its posterior outline is expanded in number, but the pygidium in his fig. 6, pI. 1 backward in the median part. In the middle part has 9 or possibly 10 ribs. The axial lobe is as. of the body there are some five pairs of depres narrow as one-fifth the pygidium. The lobe is sions on the two sides of the axial elevation evidently much narrower than in this species. which in turn is pitted and forms a beak-like Two imperfect cephala from Hitoegane which projection as far as the antero-median extremity are roundly sub triangular in outline and strongly of the hypostoma. 835. Silurian Trilobites of Hida 143

distinct from all others. Occurrence:-Limestone; Hitoegane. Two gran ulate free cheeks with long genal spines in the collection which may belong to this species as there is no other granulate cranidium.

Encrinurus cf. kitakamiensis Sugiyama, 1941 Figures 3-6

1941. cf. Encrinurus (Coronocephalus) kitakamiensis Sugiyama, Proc. Imp. A cad. , v. 17, p. 108-109, figs. 1-2. 1959. cf. Coronocephalus kitakamiensis; Hamada, Figure 5. Reconstruction of hypostoma Japan. J. Ceol. Ceogr., v. 30, p. 84-85, pI. 6, of Encrinurus fimbriatus. x4. figs. 19-20. 1974. cf. Encrinurus Kitakamiensis; Kobayashi and Hamada, Pal. Soc. Japan, Spec. Pap., no. 18, p. Observation: - The Hitoegane collection con 105-106, pI. 19, figs. 19-20, pI. 11, fig. 12, tains two hypostomata one of which (a) in Fig text-fig. 7F. ure 4-1 is found with a pygidium of this species This pygidium is sub trigonal in outline with in Figures 34a-b. It agrees with the other hypo somewhat arcuate anterior margin; axial lobe stoma (b) in essential characteristics of En about one-fourth as wide as pygidium and di crinurus and there is no other species of the vided into about 27 rings; median tubercles genus in the limestone of Hitoegane. Therefore, present on a few anterior rings, but median it is certain that the hypostoma (a) belongs to smooth band is absent. Pleural ribs 10 to 11 in Encrinurus fimbriatus. Its difference from the number; axial and pleural furrows well devel other (b) may be no more than sub specific value oped; interpleural furrows present on some an and in part a matter of preservation. terior ribs. The hypostoma (a) shows the general outline In E. fimbriatus median tubercles are more and convexity better than the other except for developed, axial rings depressed in median part, the anterior part which is broken. The latter although they do not form a median longitudinal hypostoma (b) reveals unusual lateral depressions smooth band, and interpleural furrows are in about five pairs in the middle part, but they absent. are obsolete in the former. This pygidium is closely allied to Encrinurus Comparison: -It is certain that this hypo kitakamiensis in the outlines of the pygidium and stoma belongs to the same group with those of axial lobe, numerous axial rings, number of Encrinurus and Bolizoma. Truncated by the trans pleural ribs and the presence of interpleural vers frontal margin it is pentagonal in Corono furrows. They were obscure in Sugiyama's paper cephalus and Senticulus of the Coronocepha (1941), but later they were clearly shown with linae Zhang, 1983. In its general outline and the his holotype specimen by Hamada (1959) and anterior projection of the axial part of the cen Kobayashi, and Hamada (I 974). It has neither tral body, particularly it resembles the hypo median tubercles nor a median smooth band. stoma of Bolizoma variolaris (Brongniart) (Tripp Interpleural furrows are on the other hand dis et al., 1977). In this species, however, the projec tinct in some anterior pleural ribs in that species tion takes a narrow beak-shape and the axial as in this pygidium. The axial lobe looks, how fold is provided with lateral depressions on its ever, somewhat narrower in that species. two sides in the main part of the centralloby. In Occurrence:-Shaly rock, Hitoegane. these characteristics this hypostoma is quite 144 Teiichi KOBA YASHI and Takashi HAMADA

Encrinurus cf. similis Kobayashi and Hamada, Abt. A, v. 167 (3), p. 77-119, 16 pis. --and Perry, D. G. (1984): Silurian Cheirurid trilo 1985 bites from the Mackenzie mountains (Northwest Figures 3-8a-d ern Canada). Ibid., Abt. A, v. 184, p. 1-78, 35 pis. Hamada, T. (1959): Gotlandian sr.elly fauna from 1977. Encrinurus sp. Ono, Okazaki and Hirao, Chiga Southwest Japan. (1) Coronocephalus kobayashii, ku-kenkyu, v. 28, nos. 4-6, p. 188-190. a new species from the Kuraoka district, Kyushu. Japan. Jour. Geol. Geogr., v. 30, p. 71-88. The pygidium in the above cited paper is quite --(1961): The Middle Palaeozoic group of Japan and distinct from all pygidia from Hitoegane in the its bearing on her geological history. Jour. Coli. broader axial lobe with the distinct median band. Sci., Univ. Tokyo, Ser. 2, v. 13, pt. 1, p. 1-79. Horny, R. and Bast!, F. (1970): Type specimens of fos It is sub trigonal and moderately inflated. The sils in the National Museum Pragu, vol. I, Trilobita. axial lobe is almost one-third as wide as pygidium 354 pp., 20 pis., 4 tables. and divided into more than 20 rings, and in the Igo, H. and Adachi, S. (1981): Study on the Paleozoic middle-posterior part they are interrupted by rocks in the Fukuji district, Kamitakara village, the median smooth band. A few median tuber Yoshiki county, Gifu Prefecture. Present status and unsolved problems. Jour. Geogr. (Tokyo), cles are present. The pleural lobe is divided into v. 90, no. 5 (845), p. 34-43 (336-345). about 10 non-tuberculate ribs by deep and· wide Kamei, T. (1949): On the Got!andian formation in pleural furrows, both bent back near lateral mar Hida. Jour. Geol. Soc. Japan, v. 55, p. 648-649. gin. Kobayashi, T. (1985): Division of the Silurian System This pygidium is most similar to Encrinurus and Procedure of Subcomission of Silurian Strati graphy at Present. Fossils, no. 39, p. 43-45. similis but less inflated and possesses a few more --and Hamada, T. (1965): An occurrence of a new pleural ribs. Encrinurus ishii is another similar Scutellum in the Silurian of Shikoku Island. Trans. species which differs from it by minute tuber Proc. Pal. Soc. Japan, N. 8., no. 58, p. 74-81, pI. culation of the pleural ribs. In E. tosensis the 7. median band is well developed, but median -- and -- (1974): Silurian trilobites of Japan in tubercles are absent. comparison with Asian, Pacific and other faunas. Palaeollt. Soc. Japan, Spec. Pap., no. 18, 155 pp., A pygidium in Figure 3-8 which was collected 12 pis. from the same locality has also a broad axial --and -- (1977): Devonian trilobites of Japan in lobe and median tubercles on some axial rings. comparison with Asia, Pacific and other faunas. These two pygidia belong to an identical species Ibid., no. 20, 202 pp., 13 pis. of Encrinurus closely allied to Encrinurus similis --and -- (1985): On the Silurian Trilobites and Cephalopods of Mt. Yokokura, Shikoku, Japan. from the Yokokura limestone, but distinct from Proc. Japan. A cad., v. 61-B, no. 6, p. 345-347. the two species of Hitoegane. Therefore it is --and Igo, H. (1956):·' On the occurrence of Crotalo probable that the ages of the Hitoegane and cephalus, Devonian trilobites in Hida, West Japan. Hakubado faunas are different, although time Japan. Jour. Geol. Geogr., v. 27, p. 143-155, pI. displacement may be not large. 10. Kuo Hong-tsun (1962): Some Silurian trilobites from Occu"ence:-Limestone, Hakubado, Fukui. Er-tao-quo Group of Jilian. Acta Pal. Sinica, v. 10, no. 3, p. 377-381, 2 pis. References Lane, P. D. (1971): British Cheiruridae (Tribolita). Palaeolltogr. Soc. Monogr., p. 1-95, pis. 1-16. --(1984): Silurian trilobite from Hall Land and Alberti, G. K. B. (1969): Trilobiten des jiingeren Silu Nyeboe Land, western North Greenland. Rapp. riums sowie des Unter- und Mitteldevons. 1. Abh. GrrJnlands geol. Unders., 121, p. 53-57,4 pis. Senckenberg. Naturw. Gesell., 520, 692 pp. (52 Ohno, T., Okazaki, Y. and Hirano, K. (1977): Dis pis.). covery of a Silurian trilobite at Izumi Village, Campbell, K. S. W. (1967): Henryhouse Trilobites. Fukui Prefecture. Chigaku Kenkyu, v. 28, nos. Okla. Geol. Surv. Bull., 115,46 pp., 19 pis. 4-6, p. 185-19l. Chatterton, E. D. E. and Campbell, K. S. W. (1980): Owens, R. M. (1973): British Ordovisian and Silurian Silurina trilobites from near Canberra and some Proetidae (Trilobita). Palaeontogr. Soc., Monogr., related forms from the Vasa basin. Palaeontogr., 98 pp., 15 pis. 835. Silurian Trilobites of Hida 145

Pillet, J. (1972): Les Trilobites du Devonien inferieur Japan. Proc. Imp. A cad. , v. 17, p. 106-109. et du Devonien moyen du Sud·Est du Massif Tripp, R. P. (1957): The Trilobite Encrinurus multiseg· armoricain. Soc. d'etudes sci. de l'Anjou, mem., mentatus (Portlock) and allied Middle and Upper no. 1, 307 pp., 64 pis. Ordovician species. Palaeontology, v. 1, pt. 1, p. Prant!, F. and Pribyl, A. (1947): Classification of some 60-72, pI. 11-12. Bohemian Cheiruridae (Trilobitae). Sbor. Narod. --(1962): The Silurian trilobite Encrinurus punctatus Mus. v. Praze, v. 3-B, no. 1, Geol. et Pal., no. 1,44 Wahlenberg) and allied species. Ibid., v. 5, pt. 3, pp.,6 pis. p. 466, 477, pis. 65-68. Pribyl, A., Vanek, J. and Pek, I. (1985): Phylogeny and --(1977): The Silurian trilobite Encrinurus variolaris taxonomy of Family Cheiruridae (Trilobita). Acta and allied species with notes on Frammia. /bid., Univ. Palck. Olom. Fac. Rerum Natur. Geogr.· v. 20, pt. 4, p. 847 -867, pis. 113-175. Geol., 24, v. 83, p. 107-1918 pis. Weber, V. N. (1932): Trilobites of the Turkestan. Mem. Ramsold, L. (1983): Silurian cheirurid trilobites from Comm. Geol. N. S., 178, 157 pp., 4 pis. Totland. Palaeont., v. 26, pt. 1, p. 175-210, pis. --(1951): Upper Silurian Trilobites of USSR. Trudi 19 28. VSEGEI, History of Geology, 71 pp., 6 pis. Snajdr, M. (1960): A study of the family Scutelluidae Zhang-Lu-jin (1983): On the Subfamily Coronocephal (Trilobita). Rozpravy Ustr. list. geol. Svazek, 26, inae (Trilobita). Palaeontologia Cathaysana, no. 1, 264 pp., 36 pis. p. 195-258. Sugiyama, T. (1941): A new find of Encrinurus from

~!g/!j@jLl¥-l1)nljj1!!.j[[m-:ll[ 'T i'.!iP1I1);E;Wl*c-=o:~;g~ : ~.$.J!f!:a.j~Ui~J::.~Hmj:1!!.it!!:nI1)-:ll[ 'T i'.!iP1 11) -=o:~;gi:f:t~;: Scutelluidae, Illaenidae, Proetidae, Cheiruridae, Encrinuridae ~;:Ji.i'i,-t ~ 8 ~t).J::.I1)~ Ji.i'i,ilt~;l: h -c ~,-c, .f: 11) t.c iI>~;: Kosovopeltis hidensis, Proetus (Coniproetus) tenuiceps, P. (Coniproetus ?) subconicus, Cheirurus hitoeganensis 11) 4 ~ ~ ilt ~ ;l: h -C ~, -C, Encrinurus

fimbriatus hypostomata ~ ~ ~ 0 ;:11) 7 >I" - T -Ii Ludlovian -c.f:I1):.fiEJ(;fii:f:t 11) ~ 11) li.f: 11) i:f:tf& JtIl-c;·~~o ;l: t=., ~EJ(f!;tJl:;fiP111) Encrinurus d. kitakamiensis li[lfJf&JtIlijl(li Pridolian -C;', :!!l!~

~EJ(;fiP111) Decoroscutellum (?) sp. indet. ~2.cj[[~,~f\;;11) ~ 11)-C;'~0? 0 .f: L -C-:ll[ 'T i'.!i-=o:~ ;g~tt~~cL-C-:n-ctt~*w-=o:~;g~~a~-c*ffl •• ~l1)c,.:n-ctt~~it!!~.~a~ -C;it'" ~ 711) ~ 11) C l1)"?t.cilt IJ iltWtIrb I?h~o mttJ!f!:*!l!fli~fD:iJH111) :fLliJi~i'IJl~t* B .~il"JP111) Encrinurus d. similis ~ ;:hchU:f[lfJ~f\;;I1)~I1)-C~~o 'J':f*J!i:-' iM8~± Trans. Proc. Palaeont. Soc. Japan, N. S., No. 147, pp.146-164, 8 Figs., October 30, 1987

836. SOME INOCERAMIDS (BIVALVIA) FROM THE CENOMANIAN (CRETACEOUS) OF JAPAN - II THREE SPECIES FROM HOKKAIDO, WELL KNOWN ABROAD BUT HITHERTO UNDESCRIBED IN JAPAN

TATSURO MATSUMOTO c/o Department of Geology, Kyushu University 33, Fukuoka 812

AKITOASAI Division of Geology, Department of Mineral Resources, School of Science & Engineering, Waseda University, Tokyo 160

and

HIROMICHI HIRANO Institute of Earth Science, School of Education, Waseda University, Tokyo 160

Abstract. In our recent acquisitions from the Obira and northerly adjoining Kotanbetsu areas and also from the Oyubari area of Hokkaido there are following three species, which are well known abroad but hitherto undescribed in Japan: (1) Inoceramus tenuis Mantell; This is fairly common in the lower and middle parts of the Cenomanian in the Obira and adjacent areas. Our forms are mostly smaller than but otherwise similar to the holotype from England. (2) Inoceramus gradilis Pergament; A fine example, with both valves preserved, was obtained from the Middle Cenomanian bed with Calycoceras sp. of newboldi group in the Kotanbetsu area. Ten other specimens came from Member Mh (upper part of the Cenomanian) of the Obira area. This species was originally reported from the Koryak Range of the USSR and its distribu tion is now extended to Hokkaido. (3) Inoceramus virgatus Schliiter; This species is so variable that we include in it "/. scalprum Bohm" as a synonym, giving a revised diagnosis. Examples from Hokkaido occur in the middle to uppermost part of Member Mf of the Obira area, pro bably referable to the lower Middle Cenomanian; also in the Lower Cenomanian of the Oyubari area.

Introduction works in the southern part of the Oyubari area, central Hokkaido, and the northeastern part of The main purpose of this series of papers was the Obira area, northwestern Hokkaido. written at the beginning of Part I (Matsumoto The results of these field works have been re and Noda, 1986). Succeeding to the four species ported preliminarily in Japanese by Hirano et al. described in Part I, three species from the Ceno (1981) and by Sekine et al. (1985) respectively, manian of Hokkaido are described in Part II. showing fossil localities in route maps. The They are mainly based on the recent acquisi official geological maps of the scale 1 :50,000 are tions by the Waseda University team of the available for the two areas: i.e., Nagao et al. students conducted by Hirano through field (1954) for the Oyubari quadrangle, Tsushima et al. (1958) for the Tappu (pronounced Tap) and Received July 6,1987. Igi et al. (1958) for the Horokanai quadrangles,

146 836. Cenomanian Inoceramids from Japan - II 147

the latter two of which cover the main part of field works of Waseda University and the prefix the Obira area. The Cretaceous stratigraphy of R (derived from Rumoi district) for the Obira the Obira area was described in detail by Tanaka and adjacent areas in the field works conducted (1963), whose lithostratigraphic sUbdivision is by Matsumoto. The prefix T has been used by still available and cited in this paper. There is Matsumoto since 1942 for the localities of the another work by Tanabe et al. (1977), with Saku-Abeshinai and contiguous areas in the whom Matsumoto and Hirano cooperated. northern Teshio Mountains. These T-numbers of Meanwhile, one of us (T.M.) was invited to Matsumoto appeared in Part I but are not cited Waseda University to study some of the col1ec in this part. Therefore there would be no confu tions there. Furthermore, selected specimens sion with the T-numbers of Waseda University. which T.M. examined at Kyushu University and K. Tanaka's (1963) localities in the Obira area Hokkaido University have been added to the have prefix NH. material of this study. Their localities are in the As to the subdivision of the Cenomanian Obira and Oyubari areas and also in the eastern Stage, we fol1ow Kennedy (1986 in Reyment part of the Kotanbetsu (Kotambets) area, i.e., in and Bengtson) for the definition of the Lower, the official geological map of the Soeushinai Middle and Upper Cenomanian. The three sub quadrangle (Hashimoto et al., 1(58) northerly stages have been defined on the ammonite zones adjacent to the Obira area. The fossil localities in the type area (Sarthe in the Paris Basin) and of the Kotambets area are precisely shown in can be extended to southern England and also to a route map and stratigraphic column by Matsu southeastern France. In certain sequences in moto and Okada (1973, text-figs. 7,8). Japan the correlatives of these substages are wel1 While the Cretaceous researches are continued recognized and in such cases the terms Lower, in Japan, one of us (A.A.) fol1ows the predeces Middle and Upper Cenomanian are used in this sors in the palaeontology and biostratigraphy of paper. When the correlation is not so definitive, the inoceramids. Some of Asai's col1ections from these terms are avoided and we may write, for the northeastern part of the Obira area are added instance, the lower part of the Cenomanian and to the material of this study. Also selected speci so on. Even in the former cases, it is difficult to mens of K. Tanaka's col1ections from the Obira set precisely the positions of the stage or sub area have been examined by one of us (T.M.). stage boundaries in our sequences. Although The repositories of the described or men some species of the Inoceramidae may be useful tioned specimens are as fol1ows with abbreviation for that problem, we do not intend to discuss the in parentheses: boundaries in this paper. British Museum (Natural History) London As to the abbreviated letters or symbols in (BM) the measurements, we follow those used in Part Geological Col1ections, Kyushu University, I. To avoid confusion we write in this paper BV, Fukuoka (GK) LV and RV for both valves, left valve and right Geological and Mineralogical Col1ections, valve. For brevity we may write int.m., ext.m., Hokkaido University, Sapporo (GMH) comp.int.m., etc. for the internal mould, external Geological Museum, Geological Survey of mould, composite internal mould and so on. Japan, Tsukuba (GSJ) The symbol ~ at the beginning of the measured Sedgwick Museum, Cambridge (SM) value means approximate or restored. Palaeontological Col1ections, School of Educa tion, Waseda University, Tokyo (WE) Systematic descriptions The locality numbers have the prefix Y for the Genus Inoceramus Sowerby, 1814 Oyubari area, succeeding tf) those in Matsumoto (1942), Hirano et al. (1977) etc.; the prefix T Type species: -Inoceramus cuvierii Sowerby, (derived from Tappu) for the Obira area in the 1814. 148 Tatsuro MATSUMOTO, Akito ASAI and Hiromichi HIRANO

Remarks:- Genus Inoceramus has been used figs. 3-4. 1966. Inoceramus tenuis Mantell; Pergament, p. 44, in a broad sense, but currently Mytiloides Brong pI. 23, figS. 3-4;pl. 24, figs. 1-4. niart, 1822, Sphenoceramus B6hm, 1915 and 1967. Inoceramus tenuis Mantell; Trager, p. 33, pl. 1, Birostrina J. Sowerby, 1821 are excluded from fig. 8. it as independent genera. There are still a number 1982. Inoceramus tenuis Mantell; Keller, p. 59, pl. 2, of subgenera which are affiliated to the genus fig. 2. Inoceramus and how to treat them may be a Holotype:-BM. No. 5890 (figured by Woods, problem. Such species as /. lamarcki Parkinson, 1911, text-figs. 31-32), from the Chalk Marl of /. hobetsensis Nagao et Matsumoto, /. iburiensis Hamsey, which one of us (T.M.) once examined Nagao et Matsumoto and /. teshioensis Nagao et at British Museum (Nat. Hist.). Matsumoto, all of Turonian age, are examples of Material:-WE. P014T (Figs. I-la-e) (int.m. /. (Inoceramus) in a strict sense. of BV, with inner shell layer partly preserved) For the Cenomanian species, however, little collected by A. Takagi, H. Sekine, K. Hattori and has been accomplished as to their taxonomy at H. Hirano at loco T5201a83, the Kanajiri-zawa; generic or sub generic level, aside from the WE. POll T (comp. int.m. of LV: Figs. 1-2a-c, nomenclatorially invalid or doubtful ones pro and compo int.m. of deficient RV: Fig. 1-3) and posed by Heinz (1932, etc.). For instance, /. WE. P012T (Figs. 1-4a-b) (int.m. of LV, partly crippsi Mantell is a celebrated Cenomanian species, but according to Kauffman (personal with inner shell layer) collected by A. Asai at communication to T.M. in a field excursion to a loco T6238b84 of the Jiro-zawa; all Member Mf Cenomanian locality in England, 1981) this (defined by Tanaka, 1963) of the Obira area. WE. P019T (Figs. 2-3a-c) (int.m. of BV) and five species may represent a genus independent of Inoceramus. others (1BV, 3LV and 1RV) collected by A. Asai at loco T5222b84 of the Kanajiri-zawa, Member As we have not comprehensively studied Me (or possibly Md), Obira area. One of us (T.M.) numerous species from the Cenomanian of examined also K. Tanaka's Collections from the Europe and other oversea regions, we have to use Obira area, now kept in the Museum of the Inoceramus in a fairly broad sense for the de Geological Survey of Japan, with register num scriptions of species in this paper. bers GSJ.F8215 (LV) from loco NH210 and GSJ.F8216 (BV, int. and ext.m.) from loco Inoceramus tenuis Mantell, 1822 NH617, upper reaches of the River Obirashibe' Figures 1 - 3 GSJ .F8217 (LV and immature RV) from loc: ~H419, Kaba-no-sawa and GSJ.F8218 (3 LV, 1822. Inoceramus tenuis Mantell, p. 132. Immature BV and RV) from loco NH554 all in 1911. Inoceramus tenuis Mantell; Woods, p. 271, text figs. 31-32 (non pI. 48, fig. 1). nodules of limonitic tint, upper part of Member 1928. Inoceramus tenuis Mantell; Heinz, p. 60, pI. 4, Mf which contains Calycoceras orientale Matsu fig. 2. moto, Saito et Fukada. 1959. Inoceramus tenuis Mantell; Dietze, p. 858, pI. 1, GK.HlO083 (Figs. 2-1a c) (comp. int.m. of

~ Figure 1. Inoceramus tenuis Mantell Page 148 1.a-e: WE. P014T (BV) from loco T5201a83, upper part of Member Mf, Obira area (Coll. A. Takagi and others)' nght ~ateral (a), left lateral (b, c), anterior (d), and umbonal (e) views; 1c x2, others x1.5. Scale bar = 10 mm: 2a- C •• WE. P~llT (LV) from loco T6238b84, Member Mf, Obira area (Coll. A. Asai); lateral (a) anterior (b) and postenor ( c) VIews; xl.' 3: WE. POllT (RV, deficient int.m. of the same individual as above LV) from loco T6238b84 (Coll. A. Asai)' xO. 9. Scale bar = 10 mm. ' 4a-b: WE. P012T (LV~ from loco T6238b84 (Coll. A. Asai); lateral (a) and anterior (b) views; xl. 5.; ~. P013Y (~V, With damaged apex of beak) from loco 2YC7045a79, Member M2, Oyubari area (Coll. R. ~onta); lateral view; xl. photos by courtesy of Dr. M. Noda, except Ie, 2c by A. Asai. 836. Cenomanian Inoceramids from Japan - 11 149 150 Tatsuro MATSUMOTO. Akita ASAI and Hiram ich i HIRANO

, \ \ \ \ " "- 2a' ...... 836. Cenomanian Inoceramids from Japan - II 151

LV) and GK.HI0165 (Figs. 2-2a-c) (BV, compo with the hinge-line. int.m.) collected by T. Matsumoto and H. Okada Surface ornamented with fine concentric lirae at loc. RlOO, 800 m west of the Kiritachi Pass or rings, but incipient major concentric undula (see Matsumoto and Okada, 1973), from nodules tions may appear in some individuals. of limonitic tint in a mud~tone member which contains Calycoceras of the newboldi group. Measurements:-See Table 1. WE.POI3Y (Fig. 1-5) (LV, lacking the apex of beak, int.m. partly with test) collected by R. Observation:-The holotype from the Chalk Morita at loc. 2YC7045a79, Kaneo-betsu, Mem Marl of Hamsey, a classic locality in Sussex, ber M2 of the Oyubari area (see Hirano et al., England (see Wright and Kennedy, 1984, p. 9), is 1981 ). well preserved and the description by Woods Diagnosis :-Shell rather small, inequivalve and (1911, p. 271) is clear. Its dimensions, which obliquely sub oval in outline, with the axis of were omitted by Woods and measured by one of growth nearly straight or gently concave forward. us (T.M.), are shown in this paper (Table 1). The Left valve moderately convex, with prominent length of the hinge line in the holotype is actual and incurved umbo; right valve gently convex. ly shorter than what Woods mentioned: "about Postero-dorsal part compressed. H larger than L, two-thirds of the height of the shell". The hinge line in some specimens from Hokkaido is nearly as examplified by the holotype in which L/H = 0.69 (LV) and 0.72 (RV); hinge line varied in two-thirds of the length of the shell. The ratio sll seems to vary with growth as well as between length from 1/2 to 2/3 in slL. individuals. Anterior marginal part straight and nearly SM.B42106 from the "Red Limestone" near perpendicular to the plane of valve, but antero Louth, England, which was illustrated by Woods dorsal part somewhat excavated; ventral margin (1911, pI. 18, fig. 1) under I. tenuis, is not in asymmetrically rounded, becoming more convex our opinion the named species, because it has a with growth; posterior margin gently arcuate in sub rounded-sub quadrate outline, more evenly passing from the ventral margin and then be rounded ventral margin, longer hinge line and coming nearly straight, forming an obtuse angle

Table 1. Measurements of selected specimens of I. tenuis.

Specimen Val. h I l/h H L L/H b b/h s/1 s!L ex {3 'Y 0 Holotype LV 97.0 76.0 .78 103.0 71.0 .69 34.0 .35 60° RV 87.5 76.0 .87 99.0 71.0 .72 25.0 .29 35.0 .46 .49 100° 140° 54° WE.POIIT LV - -61.5 -41 .67 -17 - -90° 54° RV -50 -37 .74 -51.5 -35 .68 -12 .24 -19 .51 .54 -90° -140° 55° WE.POI3Y LV 33.0 25.5 .77 39.0 28.0 .72 -11 .33 -18 .71 .64 WE.POI4T LV 36.0 26.7 .74 42.0 28.0 .67 12.0 .33 17.2 .64 .67 60° 130° 54° RV 29.3 24.5 .83 38.0 26.0 .68 9.3 .32 16.5 .67 .67 90° 130° 54° GK.HI0083 LV 57.0 44.0 .77 62.5 43.0 .69 27.3 .48 28.2 .69 .63 57° 130° 57° GK.HI0165 LV -86 -58 .67 - 30

~ Figure 2. Inoceramus tenuis Mantell Page 148 la- c: GK. HI0083 (LV, compo int.m.) from loco RIOO, 800 m west of the Kiritachi Pass on Highway 239 from Soeushinai to Kotanbetsu (Coli. T. Matsumoto and H. Okada); lateral (a), anterior (b) and dorsal (c) views; xl. 2a- c: GK. H10165 (BV, int.m. with deficient apex of beak) from loc. RIOO (same as above); left (a) and right (b) lateral and posterior (c) views; xl. 3a- c: WE. PO 19T (BV, int.m.) from loc. T5222b84, Kanajiri-zawa, Member Me (possibly Md), Obira area (Coli. A. Asai); x1.2. Scale bar = 10 mm. Photos by courtesy of Dr. M. Noda. 152 TatsLlro MATSUMOTO, Akita ASAI and Hiramichi HIRANO

denser lirae on the shell surface as compared with represent a specially well grown individual. the holotype and other examples. GH.H10165 (Fig. 2-2) in our material is ex The specimens from Hokkaido are mostly ceptionally large , being closer in size to the smaller than the holotype and their concentric holotype. Its concentric lirae or rings are as rings are proportionally finer. Those from Ger coarse as those of the holotype, and moreover many (Trager, 1967; Keller, 1982) and the it has incipient concentric major undulations. Pacific side of the USSR (Pergament, 1966) are One of the specimens illustrated by Pergament also more or less smaller than the holotype. In (1966, pI. 24, fig. 3) is similar to GK.HI0165 in other words, the holotype from England may these respects.

Figure 3_ Inoceramus tenuis Mantell Page 148 A number of specimens embedded in a nodule from the upper part of Member Mf at loco T5201a83 (Coil. A. Takagi and others) (see also Fig. 1-1). Scale bar = 10 mm. Photo by courtesy of Dr. M. Noda.

-+ Figure 4. Inoceramus gradilis Pergament Page 155 1a-d: GK. HI0163 from loco R100 on Highway 239 (Coli. T. Matsumoto and H. Okada); left (a) and right (b) lateral, posterior (c) and anterior (d) view s of BV. 2a, b: WE . P008T from loco T50 17e83, Kanajiri-zawa (Coli. A. Takagi and others) ; LV , RV and another RV(?) embedded with overlapping, in two views (a, b). 3a- c: WE. P016T from loco T6051h84, on the main course of the River Obirashibe (Coil. S. Ago and others); two lateral (a, b) and anterior (c) views of LV. 1,2 are natural size ; 3 slightly enlarged. Scale bar = 10 mm. Photos by courtesy of Dr. M. Noda, without whitening. 836. Cenomanian Inoceramids from Japan - II 153 154 Tatsuro MATSUMOTO, Akita ASAI and Hiramichi HIRANO

2b 836. Cenomanian Inoceramids from Japan - II ISS

Comparison:-As Woods (1911, P. 272) has in the Zone of Neostringoceras carcitanense already stated, this species resembles Birostrina (lower part of the Lower Cenomanian) and concentrica (Perkinson) but has less prominent ranges upward to the Zone of Turrilites acutus umbo of the left valve, higher value ofl/h or L/H (middle part of the Middle Cenomanian). Keller and less prominent concentric rings. Kauffman (1982) records the range of I tenuis as Lower (1978, p. iv-4) foretells briefly that there are Cenomanian to lower Middle Cenomanian in transitional forms between I tenuis and "the the sequence of Germany. Birostrina concentrica lineage", but places I On the basis of the specimens examined by tenuis in the subgenus I (Inoceramus) instead of us, the range of I. tenuis is from Member Me (or Birostrina. I (Inoceramus) should have less possibly upper Md) to Member Mf (of Tanaka, incurved and less prominent umbo of the left 1963) in the sequence of the Obira area. This valve, longer hinge line with broader postero is in harmony with the range in England and dorsal flattened wing-like area and more dis Germany, but the most characteristic occurrence tinctly developed major ribs, as compared with is in the upper part of Mf. The GK specimens of Birostrina. In these respects this species is not loco RIOO on the Soeushinai - Kotanbetsu route a typical member of I (Inoceramus). It may (Highway 239) came from the fossiliferous zone be situated at a transitional position between with Calycoceras of newboldi group, which is Birostrina and Inoceramus, or it may be rather somewhat higher than upper Mf of the Obira closer to typical species of Birostrina than to that area. This zone may be referred to upper part of of I (Inoceramus). the Middle Cenomanian, whereas N. carcitanense For the time being, we follow Kauffman to was obtained at loco R81 of the same route well refer this species to Inoceramus, awaiting the below loco RIOO (see Matsumoto and Okada, issue of the Kauffman's descriptions of the 1973,figs.7,8). Cenomanian inoceramid species from England The material from the Oyubari area is insuffi in further details. cient to tell the range and abundance of this Birostrina nipponica (Nagao et Matsumoto, species. A single available specimen came from 1939) in a revised sense (see Pergament, 1966, Member M2 (Hirano et al., 1981), which is pro p. 32) has a narrower and more incurved umbo bably referred to the lower part of Cenomanian. of the left valve than the left umbo of I tenuis. It has a smaller value of L/H and shorter hinge Inoceramus gradilis Pergament, 1966 line than those of the latter. Its axis of growth is Figures 4, S somewhat sinuous. In some of previously pub lished papers I tenuis and certain other species 1940. Inoceramus corpulentus McLearn var. a; Warren were misidentified with I nipponicus and a re and Stelck, p. 148, pI. 4, figs. 4-6. study of the so-called I nipponicus is necessary. 1966. Inoceramus gradilis Pergament, p. 49, pI. 29, figs. 2-S;pl. 31,f"Jgs.1-2;pl. 32, fig. 1. Occurrence:-According to Kauffman (1978), who studied the British inoceramids with the Holotype:-The specimen designated by Perga framework of the ammonite zonation by Ken ment (1966, p. 49, pI. 32, fig. 1) (no. 8-3580-74 nedy (1971), I tenuis occurs characteristically in the text and no. 8-3580-75 in the explanation

~ Figure 5. Inoceramus gradilis Pergament Page 155 la, b: WE. P01ST (LV) from loco TS017e83, Kanajiri-zawa (ColI. A. Takagi and others); lateral (a) and posterior (b) views. 2a, b: WE. P007T (LV) from loco TS016a83 (Coli. A. Takagi and others); lateral (a) and anterior (b) views, x1.2. 3a, b: WE. P017T (BV) from loco TS017e83 (Coli. A. Takagi and others); left (a) and right (b) lateral views. 4a-d: WE. P018T (BV) from loco TS019m83 (Coli. A. Takagi and others); left (a) and right (b) lateral, anterior (c) and umbonal (d) views. All figures natural size, except 2a, b. Scale bar = 10 mm. Photos by courtesy of Dr. M. Noda. 156 Tatsuro MATSUMOTO, Akito ASAI and Hiromichi HIRANO of plate, of which the latter may be misprinted), Sekine, K. Hattori and H. Hirano from the from the Cenomanian on the bay of Ugol'naya outcrops of Member Mh on the Kanajiri-zawa, a at the north end of the Koryak Mountains. tributary to the River Obirashibe, Obira area Material:-·At least twelve specimens from (Tappu quadrangle); WE. P016T (Fig. 4-3) (LV, Hokkaido, some of which consist of slightly dis with inner shell layer remaining on the major placed left and right valves of the same individu part) collected by S. Ago, Y. Tanaka and A. al. GK. HI0163 (Fig. 4-1) (BV, int.m., with test Matsuzawa at loco T6051 h84 from the outcrop remaining in the hinge and antero-dorsal part, of Member Mh on the main course of the River of which RV somewhat displaced towards the Obirashibe, Tappu quadrangle, Obira area. venter and its last portion is not preserved) col Diagnosis (translated from Pergament, 1966 lected by T. M. with H. Okada in 1967 from loco with some revision):-Shell small to medium RlOO, 800 m west of the Kiritachi Pass on High sized, markedly inequivalve, inequilateral and way 239 between Soeushinai and Kotanbetsu; higher than long (H > L); left valve highly con WE. P007T (Fig. 5-2) (LV, int.m., with test re vex with incurved umbo, showing stepwise maining in the anterior marginal part) from loco changes of convexity from the beak to the T5016a83; WE. P008Ta, b, c (Fig. 4-2) (LV and ventral margin with accompanied constrictions; two RV, int.m., with weathered test attaching on right valve less convex than the left but con the umbonal part of a and b, and anterior part of stricted at periodic intervals. a and antero-vental portion of b); WE. P015T Fine concentric lirae or rings on the young (Fig. 5-1) (LV, int.m., with weathered test on part up to the first constriction; fairly crowded the umbonal and anterior marginal parts); WE. concentric subcostae and/or ribs in the middle P017T (Fig. 5-3) (LV, int.m., somewhat damaged stage; major concentric ribs develop in the late at the beak and in the antero-ventra-l part; also growth-stage; sometimes ribs may be bifurcated young part ofRV, int.m., with test on the umbo or intercalated, giving rise to somewhat irregular nal part) from loco T5017e83; WE. P018T (Fig. aspect in ribbing. 5-4) (LV, int.m., with test on a portion of the umbonal part and RV of the same individual, Measurements:-See Table 2. int.m., with test on the postero-dorsal portion) from loco T5019m83; all of the above seven col Observation:-The specimens from Hokkaido lected by a field-work team of A. Takagi, H. listed above (in Material) show clearly the diag-

Table 2. Measurements of selected specimens of I. gradilis. Specimen Val. HI Ll H2 L2 bl b2 sl s2 Ll/HI L2/H2 bI/Ll b2/L2 s2/L2 GK.H10163 LV -24 22.0 45.0 30.3 15.5 -22 23.0 .91 .69 .70 .73 .75 RV 23.6 20.4 39.7 34.2 .86 .86 (sec. comp.) WE.P008Ta LV 50.5 28.0 12.5 17.5 b RV 41.0 27.5 -12 WE.POI5T LV 22.8 16.0 37.4 24.5 -11 .70 .65 .69 WE.POI6T LV 31.0 21.0 49.0 ~33.5 14.0 -20 .68 >.68 .67 ~.60 (3 = 50 0 WE.POI7T LV 33.2 25.0 -75 -35 19.5 .75 .47 .70 (sec. def.) RV 23.0 16.0 -10 13.6 .52 h=33.4 1=26.0 l/h=.78 ex= -900 WE.POI8T LV 22.6 17.0 47.0 37.4 -12 .75 .79 .70 RV 21.8 17.0 37.5 30.5 .78 .81 HI, Ll, bl, sl : measured at the fIrst constriction H2, etc. : measured at the second constriction 836. Cenomanian Inoceramids from Japan - II 157

nostic characters of L gradilis. GK. HIOl63 (Figs. I. apicalis Woods, 1912. These two species are 4-la-d) is very good in showing the left and Turonian in age. right valves of one and the same individual and Taking all the above facts into consideration, also a part of the hinge plate and thus supple we regard the similarity of L gradilis to L cor ments the holotype from the Koryak. pulentus as superficial. There is no phylogenetic Our specimens are small or medium-sized like affinity between them. the holotype and certain other examples illust The form described under L corpulentus var. a rated by Pergament (1966, pI. 28, figs. 2-5; pI. 32, by Warren and Stelck (1940, p. 148, pI. 4, figs. fig. 1) but we have not yet obtained somewhat 5-6; 4?) from the Dunvegan Formation (Ceno larger forms like those of Pergament (1966, manian) of Alberta, Canada looks very similar to pI. 31, figs. 1-2) the left valve of L gradilis, although it is smaller The axis of growth extends obliquely to the than any of the specimens as described above. postero-ventral extremity in reference to the Occurrence:-A well preserved (BV) example hinge line, which is often concealed in the left of this species was obtained from the outcrop of valve by the inflated and incurved umbonal mudstone at loco RI00 immediately after the part but can be seen inside the left valve of GK. construction of Highway 239. At the same local H10163 as well as on the dorsal margin of right ity L tenuis and Calycoceras aff. e. asiaticum, i.e. valve. e. of the newboldi group, were obtained among The abrupt change in the convexity from the others. Hence the age of this mudstone is Middle beak to the ventral margin with accompanied Cenomanian. constriction occurs in the left valve at least This species has been obtained not infre twice during the growth. We can recognize the quently at the four localities in the Obira area, corresponding constrictions on the right valve, i.e. locs. T5016a83, T5017e83, T5019m83 and although sometimes they may not be so well T6051h84 ofSekine etal. (1985), from the mud marked as those on the left valve. The dimen stone of Member Mh of Tanaka (1963), which sions at the 1st and 2nd constrictions are shown is probably referred to the upper part of the with HI, L! etc. and H2, L2 etc. (see Table 2). Cenomanian. The occurrence of both valves, with Because of the umbonal convexity or inflation, only slight displacement is noteworthy. the ratio bIlL! is fairly large (0.65-0.70). Comparison :-Inoceramus corpulentus Mc Inoceramus virgatus SchlUter, 1877 Learn (1926, p. 123, pI. 21, figs. 5-7) from the Figures 6-8 Smoky River Formation of Alberta, Canada is higher than long and much convex along the axis 1836. Inoceramus lamarcki Sowerby; Go}dfuss, p. 114, of growth, and has nearly vertical, high anterior pI. 111, fig. 2. marginal part. The plaster cast of its holotype, 1842. Inoceramus laevigatus Leymerie, p. 9, pI. 10, fig. 4. kindly sent by Dr. J. A. Jeletzky from the 1877. Inoceramus virgatus Schliiter, p. 257. Geological Survey of Canada to Kyushu Univer 1911. Inoceramus etheridgei Woods, p. 278, pI. 49, sity (GK. H9624), shows that it is evenly convex figs. 2-4. and does not show such abrupt changes as those 1914. Inoceramus scalprom Bohm, p. 599. in L gradilis. It is ornamented with fine concen 1959. Inoceramus scalprom Btihm, Moskvin, p. 142, pI. 1, fig. 4. tric lirae (nearly smooth on the intm.) in the 1966. Inoceramus scalprom Btihn, Pergament, p. 46, young stage, then weak concentric subcostae and pI. 25, figs. 1-4. weak to moderate concentric ribs combined with 1967. Inoceramus virgatusSchliiter;Trtiger,p.29,pI.1, concentric rings in the late stage. Despite its figs. 1-7. small size there is a postero-dorsal flattened area. 1978. Inoceramus virgatus Schliiter; Somay, p. 510, pI. 2, fig. 4. It is described as nearly equivalve. We agree with 1978. Inoceramus virgatus scalprom Bohm; Somay, McLearn in regarding L corpulentus as allied to p. 509, pI. 2, figs. 2,5. 158 Tatsuro MATSUMOTO, Akito ASAI and Hiromichi HIRANO

1982. Inoceramus virgatus virgatus Schliiter; Keller, (SM. B297) from the Totternhoe Stone (Zone of p. 51 , pI. 1, fig . l. Holaster subglobosus) of Burwell, England. It 1982. Inoceramus virgatus scalprum Bohm; Keller, is a left valve , whereas the topotype (another p. 54 , pI. 1, fig. 2. 1985. Inoceramus virgatus virgatus SchlUter; Kaplan, syntype) illustrated by Woods (1911 , pI. 49 , Keller and Wiedmann, pI. 8 , figs . 3,4. fig . 4) is a right valve. One of us (T. M.) once studied them at Sedgwick Museum, Cambridge. Types :-The holotype of 1. virgatus Schluter, Material:-WE. POOST (Fig. 6) (comp.int.m. 1877 is the specimen illu strated by Goldfuss of BV, with test attached in a portion) and WE. (J 836, pI. Ill , fig. 2) from Lower Saxony of POO6T (Fig. 7 -2) (int.m. of RV, with test remain Germany. None of us has examined the original ing in the postero-dorsal part) from Member Mf specimen and we depend on a photograph by at loc o TS112e83, the Korinto (Corinth)-zawa, Sornay (1978 , pI. 2, fig . 4). The holotype of 1. a branch of the Kanajiri-zawa ; WE . P003T (Fig. scalprum Bbhm, 1914 is one of the sy ntypes of 8-1) (comp. int.m. of RV) from the uppermost 1. etheridgei Woods (1911 , p. 278 , pI. 49 , fig. 3) part of Member Mf at loco TSOSla83 and WE .

Figure 6. Inoceramus virgatus SchlUter Page 157 a-d: WE. P005T (BV) from loco T5112e83, Korinto-zawa, the uppermost part of Member Mf, Obira area (ColI. A. Takagi and others); lateral view of deficient LV (a) with oblique view of RV, lateral view of RV (b), anterior view of LV (c), anterior view of RV (d) with umbonal part of LV; All figures natural size . Scale bar = 10 mm. Photos by courtesy of Dr. M. Noda. 836. Cenomanian Inoceramids from Japan - II 159

Figure 7. Inoceramus virgatus Schliiter Page 157 la- b: WE. P004T (BV) from lac. T5051c83 , the uppermost part of Member Mf, Kanajiri-zawa, Obira area (Coil. A. Takagi and others); a x I, b x 1.2. 2: WE. P006T (RV) from loco T5112e83 , Korinto-zawa, the uppermost part of Member Mf, Obira area (Coll. A. Takagi and others) ; xO.8. 3: WE . POIOT (LV) and 4: WE. P009T (RV), both from lo co T6238b84, Jiro-zawa, Member Mf, Obira area (Coll. A. Asai); xl. Scale bar = 10 mm . Photos by co urtesy of Dr. M. Noda. 160 Tatsuro MATSUMOTO, Akito ASAI and Hiromichi HIRANO

P004T (Fig. 7-1) (comp. inLm. of RV, with Surface of shell ornamented with very fine inner shell layer partly attached) from the same and dense concentric lirae and faintly perceptible horizon at loco T5051c83; all the four collected major concentric undulations, sometimes with by A. Takagi, H. Sekine, K. Hattori and H. sub costae or weak ribs on the summits of the Hirano. WE. P009T (Fig. 7-4) (comp.inLm. of undulations. Delicate radial lines or striae often RV) and WE. PO lOT (Fig. 7-3) (comp. inLm. of discernible on the internal mould, being probably LV) collected by A. Asai at loco T6238b84, the impressions of the internal structure. Jiro-zawa, a branch of the River Obirashibe. All the above occurred in the Obira area. GMH. 7247 Measurements:-See Table 3. (Fig. 8-2) (LV, comp.inLm., with test on anterior marginal part) from near the contact with Observation:-This species is fairly variable serpentine in the upper reaches of the Hakkin and we agree with Sornay (1978) who has zawa, Oyubari area. pointed out that L scalprum Bohm, 1914 (= L Diagnosis:-Shell slightly inequivalve, some etheridgei Woods, 1911) is not separable from L what inequilateral, gently to moderately convex virgatus Schluter as an independent species. in the main part of the valve and compressed in Sornay interpreted them as geographical subspe the postero-dorsal part; the left valve slightly cies, because the former is dominant in England more convex than the right; umbones terminal, and France and the latter is so in Germany. Keller and the left umbo slightly curved inward and (1982) followed Sornay in the sub specific no forward. menclature, L virgatus virgatus and L virgatus Outline of shell broadly sub oval or sub circular; scalprum, but examples of the two forms occur height being somewhat greater or nearly as great abundantly in the same area of Germany. Ac as length. Hinge line of moderate length on the cording to him the two "subspecies" are world average, forming an angle of 55° to 65° with the wide in the Lower Cenomanian and lower part axis of growth, which is nearly straight in the of the Middle Cenomanian. The coexistence of young stage or throughout growth but may the two subspecies in the same age of the same sometimes be curved gradually forward or back province with similar abundance is biologically ward in the late stage. Antero-dorsal part nearly peculiar. Should the two forms show constantly perpendicular to the plane of the valves, some the differences as tabulated by Keller (1982, times concave near the umbo; anterior margin p. 57, table 1), it would be better to separate nearly straight; ventral margin fairly convex or them as distinct species. nearly semi-circular, passing to gently arcuate We have examined the specimens from posterior margin which forms an obtuse angle Hokkaido and also illustrations of the specimens with the hinge line. from oversea areas, with the result that this

Table 3. Measurements of selected specimens of I. virgatus.

Specimen Val. h I/h H L L/H b b/h sll s/L a i3 'Y WE.P003T RV -48 -42 .88 -54 -41 .76 -28 .67 .68 -900 - 1300 60 0 WE.P004T LV -26 -22 .85 -28 -24 .86 10.0 .38 -17 .77 .71 65 0 123 0 55 0 RV -26 -24 .92 -30.5 -26 .85 5.0 .19 -17.5 .73 .67 -900 - 123 0 55 0 WE.P005T LV 33.0 28.5 .86 40.0 28.4 .71 14.0 21.0.74 .74 RV 54.8 43.2 .79 56.5 43.4 .77 13.5 .25 23.7 .55 .55 1050 - 1400 65 0 RV 92.0 77.0 .84 99.0 78.0 .79 37.0 .48 .47 105 0 - 1300 63 0 WE.P006T RV (distorted) -96 -80 .83 38.0 .47 WE.P009T RV (distorted) -50 -32 .64 23.5 .73 WE.P010T LV (distorted) -44 -41.5 .94 27.5 .66 -1000 77 0 GMH.7247 LV 75.0 70.0 .93 87.0 72.0 .83 50.0 .71 .69 105 0 - 1200 55 0 SM.B297 LV 58.2 51.4 .88 59.0 55.0 .93 -17 .29 -27 .53 .49 1100 900 ~130° -700 836. Cenomanian Inoceramids from Japan - II 161 species is so variable that it is not always sub anterior. As Somay has stated, the mode of divided into two forms. In other words, "I. preservation, such as the presence or absence of virgatus scalpntm" is merely one of varieties. For the test or the effect of secondary deformation, example, WE. P009T is higher than long (H > L) may give apparently different aspects. Therefore, but its axis of growth is concave to the anterior. we should continue to examine more examples. WE . POIOT, among many others, from the same In this paper we call this species 1. virgatus in a locality as WE. P009T, is as high as long (H = L) comprehensive concept. but its axis of growth is somewhat convex to the The examined specimens from Hokkaido and

Figure 8. Inoceramus vi!-gatus Schliiter Page 157 1: WE. POO3T (RV) from lac. T5051a83, same as for Fig. 7-1; x i. , 2: GMH. 7247 from the Hakkin-zawa near the contact with serpentinite, Oyubari area; x 1. Scale bar = 10 mm. Photos by courtesy of Dr. M. Noda. 162 Tatsuro MATSUMOTO, Akito ASAI and Hiromichi HIRANO the hitherto illustrated ones from Europe, Central Summary Asia and the Pacific province of the USSR are mostly medium sized. GMH. 7247 from the As a summary the species described in this Oyubari area is much larger than them, but paper are listed below with indication of their essentially similar to them in other characters. It known age and area in Japan. is provisionally included in this species, but we Inoceramus tenuis Mantell, common in the reserve a possibility that it could be an allied but Middle Cenomanian of the Obira and adjacent different species. areas and begin to appear in the Lower Ceno Comparison:-The affinity of this species is manian of the Obira and Oyubari areas. problematic. In the outline and gentle convexity Inoceramus gradilis Pergament, not infrequent of the valve, this species is somewhat similar to in the Middle and Upper Cenomanian of the 1. atlanticus (Heinz, 1936), but the latter has re Obira and adjacent areas. gular concentric ribs in addition to the dense and Inoceramus virgatus SchlUter, not infrequent fine lirae, as seen in the lectotype, BM. Ll038 in a zone from the Middle to uppermost part of (= I. crippsi var. reachensis Woods, 1911, pI. 49, Member Mf in the sequence of the Obira area. fig. 1), and also Gueranger's specimen (Somay, This is lower than the Tu"ilites acutus bearing 1978, pI. 1, fig. 4). 1. anglicus Woods, 1911 Member Mg and probably referable to the lower (p. 264, pI. 45, figs. 8-10, text-fig. 29) from the Middle Cenomanian; also doubtfully in the Upper Albian and basal Cenomanian of England, Lower or Middle Cenomanian of the Oyubari Germany and various regions of the world, is also area. similar to 1. atlanticus and 1. virgatus in shell These three species have been well known form, but has fairly crowded, narrow but distinct world-widely, but this is the first described and regular concentric ribs. Only on the shell record in Japan. We would expect more examples surface of its young stage the dense and fine lirae to be obtained from various areas in Japan, so are discernible. that their systematic positions and stratigraphic The group represented by these species (and occurrences may be made clearer. probably also 1. crippsi Mantell, 1822) is not the subgenus l. (Inoceramus) of the strict sense. Acknowledgements In this paper it is provisionally referred to Inoceramus of a broad sense. The shell and hinge We wish to thank Messrs. A. Takagi, H. Sekine, structure have yet to be investigated carefully. K. Hattori, S. Ago, Y. Tanaka, R. Morita and A. OCCU17'ence:-According to Keller (1982), this Matsuzawa for their kind supply of the speci species ranges from the upper Lower Cenomanian mens for this study which they obtained through to the middle of Middle Cenomanian and is the field works conducted by one of us (H. H.) distributed world-wide. when they were students of Waseda; also Dr. In Hokkaido the examined specimens from Hakuyu Okada for his kind help in the field the Obira area range stratigraphically from the work with one of us (T. M.). Thanks are ex middle to the uppermost part of Member Mf of tended to Professor Makoto Kato and Dr. Nachio Tanaka (1963). This is probably within the Minoura of Hokkaido University and Drs. Nobu range concluded by Keller, because Turrilites kazu Kanbe, Keisaku Tanaka (formerly) and acutus Passy occurs in the overlying Member Mg. Toru Sakamoto of the Geological Survey of The large specimen from the Hakkin-zawa of the Japan who generously let one of us (T. M.) in Oyubari area may have come somewhere in the vestigate freely the inoceramid specimens kept in sequence from the Lower Cenomanian Sharpei the respective institutions; also to Mr. D. Phillips ceras bearing bed to the Middle Cenomanian bed of the British Museum (Natural History) and with Cunningtoniceras sp. Mr. A. G. Brighton of the Sedgwick Museum for their kind assistance to one of us (T. M.) for the 836. Cenomanian Inoceramids from Japan - II 163 study of relevant specimens. Beitrage zur stratigraphie und Palaontologie der Dr. Jost Wiedmann of the University of mittleren Kreide, Zentral-Europe. Osterr. Akad. Tiibingen, Dr. J. A. Jeletzky of the Geological Wiss., Schriftenreihe d. Erdwiss. Komm., vol. 7, (for 1984), p. 307-347,8 pIs. Survey of Canada and Professor Kiyotaka Chinzei Kauffman, E. G. (1978): British Middle Cretaceous and Dr. Terufumi Ohno of the University of inoceramid biostratigraphy. Ann. Mus. d'Hist. Nat. Kyoto have kindly supplied us with the xerox Nice, vol. 4, (for 1976), p. iv-1-iv-12. copies of some references which were inacces Keller, S. (1981): Die Oberkreide der Sack-Mulde bei sible to us. Alfeld (Cenoman-Unter-Coniac). Lithologie, Bio stratigraphie und Inoceramen. Geol. Jahrb., Reihe We are much obliged to Dr. Masayuki Noda A, Heft 64, p. 3-171, pis. 1-8. for his friendly help in taking photographs of the Kennedy, W. J. (1971): Cenomanian ammonites from described specimens as well as for fruitful dis southern England. Spec. Pap. Palaeont., no. 8, 133 cussions. p., 64 pIs. --(1986): Ammonite biostratigraphy of the Albian to basal Santonian. In Reyment, R. A. and Bengtson, References P. (compil.): Events of the Mid-Cretaceous. Final Report on results obtained by IGCP Project No. 58, B6hm, J. (1914): Zusammenstellung der Inoceramen der 1974-1985, Appendix I. p. 129-144, pIs. 1-21, Kreideformation (Nachtrag). Jb. kgl. preuss. geol. Pergamon Press, Oxford. Landesanst., vol. 35, no. 3, p. 595-599. Leymerie, A. (1842): Sur Ie terrain cretacee du departe Dietze, H. (1959): Die Inoceramen von Oberau in ment de l'Aube, Part II. Mem. Soc. geol. France, Sachsen, Obercenoman bis Unterturon. Geologie, vol. 5, 34 p., 17 pIs. vol. 8, no. 8, p. 856-883. Mantell, G. (1822): Fossils of the South Downs; or illus Goldfuss, A. (1836): Petrefakta Germaniae. pt. 2, trations of the geology of Sussex. 320 p., 42 pIs., p. 106-118, pis. 108-115, DUsseldorf. London. Hashimoto, W., Nagao, ~. and Kanno, S. (1958): Ex Matsumoto, T. (1942): Fundamentals in the Cretaceous planatory text of the Geol. Map of Japan, Soeushi stratigraphy of Japan, Part I. Mem. Fac. Sci., nai sheet, Scale 1 :50000. Hokkaido Develop. Kyushu Imp. Univ., Ser. D., vol. 1, p. 130-280. Agency. (J). --and Noda, M. (1986): Some inoceramids (Bivalvia) Heinz, R. (1928): tiber die Oberkreide-Inoceramen SUd from the Cenomanian (Cretaceous) of Japan - 1. Amerikas und ihre Beziehungen zu denen Europas New or little known four species from Hokkaido und anderer Gebiete. (Beitrage zur Kenntnis der and Kyushu. Trans. Proc. Palaeont. Soc. Japan, oberkretazischen Inoceramen V.) Mitteil. Mineral. - N. S., no. 143, p. 409-421, pIs. 81-85. Geol. Staatsinst. Hamburg, vol. 10, p. 42-97,3 pis. --and Okada,H. (1973): Saku Formation of the Yezo --(1932): Aus der neuen Systematik der Inoceramen. geosyncline. Sci. Repts., Dept. Geol., Kyushu Univ., (Beitrage zur Kenntnis der Inoceramen XVI.) Ibid., vol. 11, no. 2, p. 275-309 (J). vol. 13, p. 1-26. McLearn, F. H. (1926): New species from the Colo --(1936): Inocenimidos de Alicante, Valencia y radoan of Lower Smoky and Lower Peace Rivers, Baleares (lnoceramen 15). Bol. Soc. Esp. Hist. Nat., Alberta. Geol. Surv. Canada, Bull., vol. 42, p. 117- vol. 36, no. 2, p. 91-99, 1 pI. 126, pIs. 20-23. Hirano, H., Matsumoto, T. and Tanabe, K. (1977): Mid Moskvin, M. M. (1954): Atlas verchnemolovo; fauny Cretaceous stratigraphy of the Oyubari area, central serernogo Kavkaza i Kryma. 130 p., 23 pIs., Hokkaido. Palaeont. Soc. Japan, Spec. Pap., no. 21, Moscow (R). p.1-10. Nagao, S., Osanai, H. and Sako, S. (1954): Explanatory --, Ando, H., Hirakawa, M., Morita, R. and Ishikawa, text of the Geol. Map of Japan, Oyubari sheet, T. (1981): Biostratigraphic study of the Cretaceous Scale 1 :50000. Hokkaido Develop. Agency. (J). System in the Oyubari area, Hokkaido Part 2. Nagao, T. and Matsumoto, T. (1939): A monograph of Gakujutsu Kenkyu, School of Education, Waseda the Cretaceous Inoceramus of Japan. Part I. Jour. Univ., Ser. Bioi. & Geol., vol. 30, p. 33-45 (J). Fac. Sci., Hokkaido Imp. Univ., Ser. 4, vol. 4, Igi, S., Tanaka, K., Hata, M. and Sato, H. (1958): Ex p. 241-299, pIs. 23-34. planatory text of the Geol. Map of Japan, Horo Pergament, M. A. (1966): Zonal stratigraphy and kanai sheet, Scale 1 :50000. Geol. Surv. Japan (J). Inoceramus of the lowermost Upper Cretaceous of Kaplan, U., Keller, S. and Wiedmann, J. (1985): Am the Pacific coast of the USSR. Trans. A cad. Sci. moniten- und Inoceramen-Gliederung des nord USSR, Geol. Inst., vol. 149,83 p., 36 pIs. (R). deutschen Cenoman. In Kollman, H. A. (ed.); Schliiter, C. (1877): Kreide-Bivalven. Zur Gattung 164 Tatsuro MATSUMOTO, Akito ASAI and Hiromichi HIRANO

Inoceramus. Pali1ontographica, vol. 24, p. 249- Turons Mitteleuropas. Abh. Staatl. Mus. Mineral. 288, pIs. 36-39, Stiittgart. Geol., vol. 12, p. 13-207,14 pIs. Sekine, H., Takagi, A. and Hirano, H. (198S): Bio Tsushima, K., Tanaka, K., Matsuno, K. and Yamaguchi, stratigraphical study of the Upper Cretaceous of S. (19S8): Explanatory text of the Geol. Map of the north-east part of the Obira area, Hokkaido. Japan, Tappu sheet, Scale 1:S0000. Geol. Surv. Fossils, Palaeont. Soc. Japan, no. 38, p. I-IS (J). Japan (J). Sornay, J. (1978): Precissions paleontologiques et Warren, P. S. and Stelck, C. R. (1940): Cenomanian and stratigraphiques sur divers Inocerames Cenomaniens Turonian faunas in the Pouce Coupe district, et, en particulier, sur ceux de la Sarthe figures par Alberta and British Columbia. Trans. Roy. Soc. E. Gueranger en 1867. Geobios, vol. 11, no. 4, p. Canada, Ser. 3-d, vol. 34, Sec. 4, p. 143-1S2, pIs. SOS-SIS, 2 pIs. 1-4. Tanabe, K., Hirano, H., Matsumoto, T. and Miyata, Y. Woods, H. (1911): A monograph of the Cretaceous (1977): Stratigraphy of the Upper Cretaceous Lamellibranchia of England. vol. 2, part. 7, Pala deposits in the Obira area, northwestern Hokkaido. eontogr. Soc. Monogr. for 1910, p. 261-284. pIs. Sci. Repts., Dept. Geol., Kyushu Univ., vol. 12, no. 4S-S0. 3, p. 181-202 (J). --(1912): Ditto, vol. 2, part. 8, Ibid. for 1911, p. Tanaka, K. (1963): A study on the Cretaceous sedimen 28S-340, pIs. Sl-S4. tation in Hokkaido,Japan.Rept. Geol. Surv. Japan, Wright, C. W. and Kennedy, W. J. (1984): A monograph no. 197,122 p., 2 maps, 3 pIs. of the Ammonoidea of the Lower Chalk. Part 1. Troger,K.-A. (1967): Zur PaHiontologie, Biostratigraphie Ibid., p. 1-126, pIs. 1-40, (Pub. No. S67, part of und faziellen Ausbildung der unteren Oberkreide vol. 137 for 1983). (Cenoman bis Turon). Teil I PaHiontologie und (R): in Russian. (J): in Japanese with English abstract. Biostratigraphie der Inoceramen des Cenomans bis

Abeshinai 'tCf.=E;p;j, Hakkin-zawa B~iR, Horokanai ~bnp;J. Jiro-zawa lXJl~iR, Kaba-no-sawa :fJ /~ / iR, Kanajiri-zawa ~miR, Kaneo-betsu ~.I'f!5]U, Kiritachi fJli., Korinto (Corinth)-zawa ::r !! :,/ I- iR, Kotanbetsu (Kotambets) i;fJ-5]U, Obira Ij'f, Obirashibe ,j'f~, Oyubari :k6'51, Rumoi ~lijf, Saku fti:~, Soeushinai jf.;lj:.p;j, Tappu (Tap) ~:ffl, Teshio :;R.I;\!.

*~B.*~/7=7:'/~.~/~5A~-D . • ~~1<~~h*~~~*~~~~~k3 ~ : ~t.~.O)~*~c£-:) ~lXO) 3 ~~~G)(!i . 1ZIjf- Lt.:. (.E!. L~:g~cltJ1>iJUnoceramus ~I'~ 8':J~cre? (1) Inoceramus tenuis Mantell. tc;b;lJ'~~, ;f411b~c}j£tft,:/HI!lO)*g~M, Ii'lJ'L'F9tUWHDiJ~~ 7.:> t.: vt"('ffrt~cjlfl,'iJ~, ,ijl(;~~M~cli'lJ'L.'F9:1*:II!9f*:iJ;~~ <.fe~-r7.:>:: ciJ~~7.:>. Birostrina concentrica ~c1J;J.7.:> iJ~, tc~lJHflliJ~m < , p;j::iJf:BlIIliJ~~~ < , ~*.lJliJ~~~~ <~'W$iJ~ OOlit~C3f:!!HI::-r 7.:>. 'j'f, i;fJ-5]U!1!!J;gl(c :k6'51!1!!J;gl(0)~ /7 = 7 :'/"F$~. (2) I. gradilis PergamentJj,~. ;b~lt~ I) J: I) iJ;(g;I,'iJ~%JJ;t Lt.: . ~O)~mu ItJ5!:~8':J~C(i)~1v Effrt, (1i)1i'lJ'L.'F9:1*:O)~~/j'HD, (iii)OOlitt.J:HDO).fe~ c ~(I:: L, )ttt· ~A.iJt~ I) ~~;IJ'~IB!u~~7.:>. ;b~ltI. reduncus Pergament ciJ,t.J:'J1J;J.'"(I,'7.:>. i;fJ-5]Uc /j'fO).p$· J: $~ /7= 7 :'/~c.-r7.:>. (3) I. virgatus SchlUter.tt*5]U~JUt.~c t!:h '"(I, ,t.: I. scalprum Bohm ~1i'lJ-~p;j0) 1 ~Jr: c L, qj(lE~aLt.:. tc;b*~~~, ~ltf:!!!~cjlfl,'iJt, tc~lt~~?ilii IJ, ~~~~*.lJl~j,'L.. ~*- '"(1,'7.:>. *F9MiJ'::k~O)*g~M~, H c LI;l:t;tt:f~~iJ', I.' L ; ~~I;l:~ <, ,ijl(; ~flBI;l:::h~55'~65' ~iil:!*.lJl:l*:~c~ I), ~WJ~cilrJJZ.I;l:r~::iJtc[!:!]O)~7.:> l,'IIIl*.lJl~td-:: c ~ ~7.:>. ~~iIfftCIi'lJ'L.'F9:1*:O)*JIIWtdk*.lJl c ~ 7.:> I, '1I!9f*: (}jj]O)ilii~~~It) iJ~~7.:>. :: O)II!9f*:iJ~ ~ ~ c!li . ~p;jiIfftc1&M:I*:O)~*.lJliJ~~to I) ~1Ib ~h7.:>. 'j'f!tl!J;gl( Mf 0). a*~D'~*OOA'fH£~ Trans. Proc. Palaeont. Soc. Japan, N. S., No. 147, pp. 165-179,8 Figs., October 30,1987

837. ONTOGENETIC SHELL VARIATION AND STREAMLINING OF SOME CRETACEOUS AMMONITES*

KAZUSHIGE TANABE and YASUNARI SHIGETA Geological Institute, University of Tokyo, Tokyo 113, Japan

Abstract. Comparative shell shape analysis of some Cretaceous ammonites has provided significant differences in the ontogenetic pattern and variation of geometric coiling parameters. The differences are especially conspicuous in the distance of venter from coiling axis (D), rela tive whorl thickness (S) and flank position (F), all of which are key factors for considering hydrodynamic efficiency of the shells. In every species, the ranges of variation of the geometric parameters tend to decrease with age. At the same growth stage, intraspecific variation of parameters Sand D is largest in the heavily ornamented morphotypes (Acanthocerataceae) and heteromorphs (Scaphitaceae), intermediate in fine-ribbed platycones (Lytocerataceae), and smallest in the weakly ribbed, highly streamlined involute-compressed morphotypes (Hypophylloceras, Placenticeras and most Desmocerataceae). This evidence strongly suggests a wide variety of adaptive designs of the shells related to the mode of life of ammonites.

In trod uction Hydrodynamic efficiency of shell shape in fossil ectocochiliates has recently been discussed by The paleoecology of ammonites has long been Ward (1980) and Chamberlain (1981). These discussed from various viewpoints. Although papers rely on generic level analysis of certain opinions on life habits are still divided as to simple shell shape parameters over various whether ammonites were bottom dweUing or taxonomic groups. Intra- and interspecific varia nektoplanktonic, many authors have accepted tion of shell shape has also been examined the idea that most normally coiled ammonites extensively in the Upper Paleozoic Agoniatitida had a certain degree of swimming ability. This and Goniatitida (Kullmann and Kant, 1970, interpretation is largely based upon indirect 1972; Kant, 1977; Kant and Scheuch, 1973, paleontologic evidence such as comparative 1980; Saunders and Swan, 1984) and Mesozoic anatomy (Mutvei, 1964; Mutvei and Reyment, Ammonitida (Westermann, 1966; Bayer and 1973; Jordan, 1968; Stiirmer, 1970; Lehmann, McGhee, 1984; Ward, 1980, 1986), but the 1976) and similarity in fundamental shell mor ontogenetic variation of shell geometry has little phology to living Nautilus (Trueman, 1941). investigated in the Cretaceous ammonites. This Quantification of hydrodynamic properties of paper presents quantitative data on the ontogene ectocochiliate cephalopod shells has been made tic change and variation of shell shape in some experimentally using actual specimens (Schmidt, late Cretaceous ammonite species, and discusses 1930; Kummel and Lloyd, 1955) and scale their adaptive significance for streamlining. models (Chamberlain, 1976, 1981; Chamberlain and Westermann, 1976). The experiments de Material and methods monstrated that the variation in shell geometry caused significant variation in drag coefficients. Material-Twenty Cretaceous ammonite spe cies listed in Table 1 were treated in this study. *Received July 23, 1987; read February 2, 1985 at Most species are represented by several individ University of Tokyo. uals which were preserved in single calcareous 165 166 Kazushige TANABE and Yasunari SHIGETA

Table 1. List of material. Samples with prefix R are from the Cenomanian-5antonian of the Obira area, northwestern Hokkaido (see Tanabe et ai., 1977, figs. 4-11 for localities and ages). The localities and ages of the remaining samples are as follows. M135 and PM3007: Upper Turonian of the Manji area, central Hokkaido (see Tanabe et ai., 1978, fig. 1 for localities), S221lp and S3006: Lower Campanian at Matsumoto's (1942, pi. 12) loco T281, middle course of Abeshinai River, Saku area, northern central Hokkaido, Hb-lO: from river gravel in the upper course of Nakafutamata River, Haboro area, northwestern Hokkaido (derived from the Coniacian).

Major taxonomy Species Sample & locality

Phylloceratina Phyllocerataceae Hypophylloceras subramosum (Spath) R4018 (N= 5) , Obira Lytoceratina Lytocerataceae Tetragonites glabrus (Jimbo) R4020 (N= 6), Obi ra Tetragonites popetensis Yabe S3006 (N=I7), Saku Gaudryceras denseplicatum (Jimbo) R4020 (N= 5), Obi ra Ancyloceratina Scaphitaceae Scaphites planus (Yabe) R2110 (N= 4), Obira Otoscaphites puerculus (Jimbo) R2110 (N= 7), Obira Ammonitina Desmocerataceae Desmoceras japonicum (Yabe) R3013 (N= II) , Obira Tragodesmoceroides subcostatus Matsumoto R4001 (N=18), Obi ra Damesites ainuanus Matsumoto R4582 (N=12) , Obi ra Damesites damesi (Jimbo) R470Ip(N=11) , Obira Damesites semicostatus Matsumoto R2672 (N=I7), Obi ra Damesites sugata (Forbes) Hb-IO (N= 8), Haboro Desmophyllites diphylloides (Forbes) S221Ip(N= 6) , Saku Neopuzosia ishikawai (Jimbo) RI 01 p (N= 6), Obira Acanthocerataceae Subprionocyclus bravaisianus (d'Orbigny) R4017 (N= 6), Obira Subprionocyclus neptuni (Geinitz) PM3007(N=14), Manji Reesidites minimus (Hayasaka & Fukada) MI35 (N=13) , Manji Yubariceras yubarense Matsumoto, Saito & Fukada R6020 (N= I), Obira Yubariceras japonicum Matsumoto, Saito & Fukada R4020 (N= I) , Obira Hoplitaceae Placenticeras intercalare Meek USGS loc. no.8036 Nautilida (N= I), Montana Nautilaceae Nautilus pompilius Linne Off Suva, Fiji Is. (N= 9)

nodules embedded in the Upper Cretaceous records), and nine Nautilus pompilius Linne deposits of Hokkaido, Japan. The localities and (captured from the Suva area of FiJ'i', Tanabe , ages of the samples examined are summarized 1985) were used for morphologic comparison. in the explanation of Table 1. Specimens of Specimens of the two scaphitids andN. pompilius Scaphites planus and Otoscaphites puerculus are stored at Kyushu and Kagoshima Universities were studied biometrically by Tanabe (1977), respectively. All other specimens are kept at and measurements by him are cited in this paper. University Museum, University of Tokyo with In addition to these ammonites, single mature registered numbers beginning UMUT. shells of Placenticeras intercalare, Yubariceras Methods-Most specimens were cut and yubarense, Y. japonicum (see Table 1 for locality polished along the median plane, and then cut 837. Ammonite Shell Variation and Streamlining 167 perpendicular along the maximum diameter of such as the "strength" and density of external the protoconch (X-Y plane in Figure 1). The SCUlpture (ribs, tubercles and a keel) were not cross sections were etched with 1% acetic acid analyzed quantitatively, but considered in the for ten minutes, and acetate peels were prepared morphotypic classification. by pressing a sheet of triacetylcellulose mm (25 11m in thickness) onto the section flooded Morphotypic variation with acetone. Shell diameter, radius vector of venter, radius vector of umbilicus, whorl h~ight, Although the Cretaceous ammonites examined whorl breadth and inner whorl height were vary in coiling, whorl shape, and surface orna measured at intervals of one half whorl on the ment, they possess characteristic features of shell peeled cross section using a profile projector morphology. They are roughly classified into the (NIKON V16) attached to a digital micrometer following morphotypes: (1) narrowly umblicate (accuracy 111m) (Figure 1). The measurement and compressed with fine ribs (Hypophylloceras, data were transferred directly to a personal com Desmoceras, Tragodesmoceroides, Desmophyl puter through an interface, and the four geomet lites, Placenticeras) or with fine ribs and a ric parameters developed by Raup (1966, 1967) prominent keel (Damesites), (2) moderately and Chamberlain (1976); i.e. the whorl expan umbilicate platy cone with dense fine ribs (Tetra sion rate (W), the distance of venter from coiling gonites and Gaudryceras), (3) widely umblicate axis (D), the relative whorl thickness (S), and the and compressed with strong ribs, tubercles flank position (F) were calculated at intervals of (Yubariceras) and also with a keel (Subprionocy one half whorl for each specimen (Figure 1). clus and Reesidites), and (4) planispirally coiled Other important aspects of shell morphology, heteromorph (Scaphites and Otoscaphites). Se lected examples of these ammonites are shown in Figure 2.

MEDIAN SECTION CROSS SECTION (HALF) x x Geometric analysis

Ontogenetic variation-Ontogenetic changes of geometric parameters were examined in seven teen Cretaceous ammonite species. Changes of sample means of parameters W, D, Sand F versus whorl number for each species are shown in Figures 3-6 respectively. In every species, parameter W regularly fluctuates between 1. 5 and 2.5 at intervals of one whorl in the first three whorls. This is largely due to the abrupt change in allometric growth of whorl radius at y y the primary constriction near the end of the first

GEOMETRIC PARAMETERS: w=(b/C)2.D=g/b. S=d/e. F=fla whorl. After the third whorl most species have W parameters of about 2.0, but in the scaphitids W Figure 1. Basic morphology and measurements exceeds 3.5 in the loosely coiled adult stage of an ammonite shell in median and cross sections. a, shell diameter; b & c, radius vector of venter; d, whorl (Figure 3). D parameters of Hypophylloceras height; e, whorl breadth; g, radius vector of umbilicus; subramosum and most desmoceratids decrease f, inner whorl height. Based on these measurements, with age in the first three whorls, and after the four geometric parameters, W (whorl expansion rate), D third whorl remain almost constant (ca. 0.1) (distance of venter from coiling axis), S (relative whorl (Figure 4). In Neopuzosia ishikawai (Desmoce thickness), and F (flank position) were calculated at intervals of half whorl. Read S = eld for S = dIe. rataceae) D is also small in the second and third 168 Kazushige TANABE and Yasunari SHIGETA 837. Ammonite Shell Variation and Streamlining 169

r Hypophyltoc.,.s ,ubremo.um 13 Desmophylllle. dlphyllolde. 2 retr.ganlts. gl.bTU. 14 Neopuzosl. Ishikawa' J refragonlt •• pOpete"s/s 15· Subprlonocyc/us bra~lI/slllnus t\, 4 Gaudryce,.s dens.plle.tum 16 Subprlonocyclus nap'unl , 5 Scaphltes pla"us 17 Reesldlt.s mlnlmu, ...... :,\ 6 Otoseephlls. puercu/us ADULT 3.5 7 De,moce,.s Japon/cum STAGE 8 rragodesmoceroldes sUbeosl.tus

9 Oemsslt.s a/nusnus 10 Dameslt.s damesl

It Damesltes sam/cost.tus 12 Damesltes sugat.

3.0 -~

W I- « ex:: z 0 2.5 (f) Z « a. X W ....J a:: 2.0 0 I ~

o PHYLLOCERATACEAE

1.5 6LYTOCERATACEAE

<>SCAPHITACEAE

o DESMOCERATACEAE

OACANTHOCERATACEAE

1.0 1.5 2 2.5 3 3.5 WHORL NUMBER Figure 3. Ontogenetic change of the parameter W in relation to whorl number for seventeen ammonite species. Sample mean at each stage is plotted for every species. The regular fluctuation of W parameters in the flrst two whorls is due to the abrupt change in growth of whorl diameter at the primary constriction.

+- Figure 2. Wide variation of shell shape and surface ornament observed in selected Cretaceous ammonites. Lateral (A) and ventral (B) views are shown for each species. For locations see Table 1. lA-B. Yubariceras japo nicum Matsumoto, Saito & Fukada (UMUT MM 18213; XO.2). 2A-B. Subprionocyclus bravaisianus (d'Orbigny) (UMUT MM 18209; XO.8). 3A-B. Otoscaphites puerculus (Jimbo) (Kyushu Univ. specimen, GK. H 5753; X1.6). 4A-B. Gaudryceras denseplicatum (Jimbo) (UMUT MM 18200; XO.3). 5A-B. Damesites semicostatus Matsumoto (UMUT MM 18205; XO.8). 6A-B. Hypophylloceras subramosum (Spath) (UMUT MM 18197; XO.8). 7A-B. Placenticeras intercalare Meek (UMUT MM 18214; XO.26). 170 Kazushige TANABE and Yasunari SHIGETA whorls but then increases abruptly. D parameters growth stage. Two scaphitids possess extremely of other species are almost constant throughout large D parameters in the adult stage. In every growth (ca. 0.3-0.5) and larger than in Hypo species examined, parameter S tends to decrease phylloceras and most desmoceratids at the same with age (Figure 5). At the same stage, it is

I Hypoph.,lIoc.t.s subnmosum II Oame.sltes sam/cost.,us 2 re,ragonlfes g/abrus 12 Dam.slles sugat. 0.6 J T.".gonlles poparens/s IJ Oesmophrllltes dlph'liloides

.. Geud''1Ce'8S dens.pllcarum ,. NeoPuzosJ. Ishllu,wal 6 ADULT 5 SC8phlles planus 15 Subprlonocyclus brett./s/enus STAGE 6 Otosceph"es pU.feu/us 16 Sub,ulonocyc/us neplunl 7 Desmoceras lap on/cum 17 Re.s/dltes m/nlmus 8 Tragodesmoceroldes subcost.lus

9 Dames/les .'nuanus 0.5 ADULT STAGE

(/) x « 0.4 (!) Z ...J o ()

~ o 0.3 0: u. 0: W I Z W > 0.2 U. o w () z « l- (/) 0.1 o PHYLLOCERATACEAE C ~LYTOCERATACEAE OSCAPHITACEAE o DESMOCERATACEAE o ACANTHOCERATACEAE

D~~--~----~--~----~--~----~4-----L----5~ 1.5 2 2.5 3 3.5 4.5 WHORL NUMBER

Figure 4. Ontogenetic change of the parameter D in relation to whorl number for seventeen ammonite species. Sample mean at each stage is plotted for every species. In the third to fIfth whorls, D parameters of the Phyllocerataceae and most Desmocerataceae are much smaller than those of other superfamilies. 837. Ammonite Shell Variation and Streamlining 171 smallest in the species of the Phyllocerataceae species examined (Figure 6). It increases rapidly and the Acanthocerataceae, intermediate in the with age in Hypophylloceras or slowly in Tetra Desmocerataceae, and largest in the Lytocera gonites, Gaudryceras and Reesidites. F parameters taceae and the Scaphitaceae. Ontogenetic change of most desmoceratids are relatively large (ca. of parameter F also varies greatly among the 0.30) and remain almost constant during onto-

2.0 1 H'IPophyllocer.s .ubramosum 11 Oame./r •• • em/co.,.tu. 2 ru,.gonlte. glabrus 12 Dameslte. luga'. 3 r.,r.gonlta. pope'ens/s 13 Oesmophyillt •• dlphyllo/de. 1.9 4 Geudryce,e. dens.pllcarum 14 Neopuzosl. Ishlkawal 5 Seep"".s planus 15 subprlonocycJus br.".'s/anus 6 Oro.cepll,r •• puerculu. 16 Subprlonocyclus fte."tunl 1.8 7 O •• moc.,., lapon/cum 1 7 R.e.'dUes mlnlmu. 8 Tragode.mocerolde. subcos,.tus

9 Dame.It.. ./nuenu. 1.7 10 Demeslt.s demesl

1.6

1.5

1.4 (J) (J) UJ Z 1.3 ~ () I 12 I- ...J a: 1.1 o I 3: 1.0 UJ > l 0.9 e:( ...J O)HYLLOCERATACEAE UJ a: 0.8 6.L YTOCERAT ACEAE

OSCAPHITACEAE 0.7 ()OESMOCERATACEAE

ACANTHOCERATACEAE· 0.6 o

O.5L-J---~1.~5----2~--~2~.5----~3--~3~.5~--~4--~4~.5~--~5~

WHORL NUMBER Figure s. Ontogenetic change of the parameter S in relation to whorl number for seventeen ammonite species. Sample mean at each stage is plotted for every species. In every species S decreases with age, but the interspecific variation at the same whorl stage is fairly large. 172 Kazushige TANABE and Yasunari SHIGETA geny. The only exception is Neopuzosia ishikawai in two sets of S-D and W-F diagrams at different with F gradually decreasing. growth stages (Figures 7-8). In every species, Intra- and interspecific variation-Shell shape intraspecific variation of geometric parameters variation in the species examined is summarized is larger in the early stage than in the later stage.

0.45 2 r.'r.von"as {l1.btus 7 Oe5moc.,eS lap on/cum 15 Subprlonocyclus br.".'s'.nus 3 Tetr.VonUes poperens/s 8 rragodesmoc.f'olde. subcost.tus 16 Subpr/onocyc/cJ$ ne,,'u"' 9 Oemeslle. .Inuenus 10 Oames't •• demesl

II Oameslte. semlcos'.'us OPHYLLOCERATACEAE 12 Oam.,"a, ,.ge,e

LJ.LYTOCERATACEAE 13 O.,mophyll"., dlphylloldu 0.40 OSCAPHITACEAE o DESMOCERATACEAE 0.35 oACANTHOCERA TACEAE

0.30 ...... lJ.. z o t-

~ 0.25 a..

~z ~ ....J 0.20 lJ..

0.15

0.10 '---'---_--L__ L-_...L-_--L __ L-_--L_--'- __..l.- 1.5 2 2.5 3 3.5 4 4.5 5 WHORL NUMBER

Figure 6. Ontogenetic change of the parameter F in relation to whorl number for seventeen ammonite species. Sample mean at each stage is plotted for every species. Wide interspecific variation can be observed among the species examined at the same whorl stage. 837. Ammonite Shell Variation and Streamlining 173

I Hrpophrlloce,e. subremosum 11 Dam."' •• •• mlcost.,us o PHYllOCEAAYACeAe 2 Te"8gon"8. gl.btus til YTOCERATA.CEAE 3 Terrago,," •• poperens's 13 Desmopll,,,,, .. dlphrllo'du 0,5 o SCAPHIT ACEAE 4 Geudlre.,•• dens.pllce'um '4 Neopuzo.'. ,.h'leew8' o oeSMOCERATACEAE 5 SeephU •• pl.trus 15 $ubP,'onoc,cI"s br.".'.'anus a ACANTHOCERA T ACEAE 6 arose_phU •• puefculus 16 Subprlonocrc/"s naptunl o 7 D •• moee,•• laponlCl/m 17 R ••• ldlt •• mlnlmus en B Tregodasmocerold •• subcosr.,us XO.' « Cl z ..J o o u. ::; 0,3 0,' o Z a: 0 u. I-- .... a: IU en .... I-- 0 Z "- w 0.7 0,3 > u. Z o «'" " ..J IU u. o Z « .... 0,1 0,2 en Ci

°07'5-----!---~I:';,5---~;------:2:':,5- 0~'~5----~------~I,~'5-----~------2~,'5

RELATIVE WHORL THICKNESS (S) WHORL EXPANSION RATE (W)

Figure 7. Variation of the geometric parameters at the end of the lust whorl in seventeen ammonite species. Sample mean and two standard deviations (horizontal and vertical lines) are indicated for each species. The two figures indicate similarity in juvenile shell morphology among the Cretaceous ammonites.

The species examined do not show significant stage also vary greatly among these species (Table differences in juvenile shell morphology (Figure 2). Interspecific difference in the sample mean is 7). In contrast, they show a large interspecific especially conspicuous for parameters S, D and variation in the later growth stage (Figure 8). F. Based on these observations we consider the The coefficients of variation of parameters Sand morphologic adaptations of the high variation in D at the fourth whorl stage are usually largest in shell geometry. Truly remarkable intraspecific the Acanthocerataceae and Scaphitaceae, inter variability has been recognized in many near mediate in the Lytocerataceae, and smallest in shore-type Acanthocerataceae and Hoplitaceae, the Phyllocerataceae and Desmocerataceae, at such as in species of Acanthoceras (Kennedy and least for the samples examined (Table 2). Geo Hancock, 1970), Collignoniceras (Kennedy et al., metric parameters of adult Placenticeras inter 1980), Pseudotissotia and Wrightoceras (Hirano, calare and Hypophylloceras subramosum are 1983), and Neogastroplites (Reeside and Cobban, very similar to those of Nautilus pompilius 1960). In contrast, shell shape variation is much (Figure 8). smaller in the offshore-type ammonites investi gated such as Gaudryceras (Hirano, 1975, 1978) and Tetragonites (Y. Shigeta's unpublished data). Discussion Two major adaptive strategies have been con~ This study demonstrates that the shells of sidered for the function of ammonite external Cretaceous ammonite species examined differ shell morphology: (l) protective (defensive) in in coiling at all ontogenetic stages. Coefficients thick-shelled whorls with spines or prominent of variation of parameters at a given growth ribs preventing shell breakage by predators 174 Kazushige TANABE and Yasunari SHIGETA

t Hypophrlloce,.s .ubramo.um 6 oro.cap/dt•• puereulus 11 Dama,lt •• sem/co,'.'u. 16 Subprlonocyclu. neptunl 2 T.rragonlta. ,,'abrus 7 D•• mocer •• /aponlcum '2 Oameslr.s sug.,. 17 R•• "dlt •• mlnlmu. 3 TerragonUe. poparansls 8 Tregoda,moc.rold •• subcost.rus 13 D •• moph''''t •• dlphyllolda. 18 Yuber/e., •• yuba,en •• 4 Geud,yce,a. dans.plle.fum 9 Dam ••', ••• Inuanu. 14 Neopuzos/. ,,"'lrawa' 19 Yub.,/cer•• 'apon/cum 5 Seaph" •• pl• ."us 10 Oameslte. dame.1 15 Subprlonocyclus bra".','anu, 20 PI.centlcer•• ,",.,e.'.,. 21 Nautilus pomplllu,

0.5 D.S

a ~+ x 0' D.~ c(

(!) Z ...J !r- u:: + o o I 0.3 z ::; 0 0.3 I~ rr- o I- a: ,I u. + ...J PItYllOCERATACEAE u. U. 1 0 o I::; lYTOCERATACEAE w o SCAPHITACEAE z 0 o DESMDCERATACEAE ~ 0.1 >0:1 l!L!1 D. 1

o .______L_ ____-'- _____~IL--- o o D.S 1.5 1.5 2.5 3.5 RELATIVE WHORL THICKNESS (S) WHORL EXPANSION RATE (W)

Figure 8. Variation of the geometric parameters at the middle of the fifth whorl in seventeen ammonite species. Data of adult shells of three ammonite species (nos. 18-20) and Nautilus pompilius are also indicated for comparison. Sample mean and two standard deviations (horizontal and vertical lines) are indicated for each species. Intraspecific variation of parameters S and D is especially small in the Phyllocerataceae and the Des mocerataceae. Hypophylloceras (no. 1), Placenticeras (no. 20) and modern Nautilus (no. 21) possess similar geometric parameters.

(Westermann, 1971; Ward, 1980) and (2) hydro used cephalopod scale models with round-whorl mechanical for increasing swimming ability sections (S = 1) and smooth surfaces, and meas (Chamberlain, 1976, 1981; Chamberlain and ured drag coefficients acting on the shells at Westermann, 1976). These two strategies are various water velocities. For aquatic animals the largely exclusive because hydromecanica1 ef drag force acting on a swimming body can be ficiency decreases as the external ornament be approximated by the following equation. comes more prominent (Kummel and Lloyd, 1955; Chamberlain and Westermann, 1976; Chamberlain, 1981). Quantitative analysis of the relations between shell geometry and drag coeffi where D F is drag force, p is fluid density, V is cients in the ectocochiliate cephalopod shells swimming velocity, A is equivalent to a body size has been done by Chamberlain (1976, 1981). He (shell size in this case), and CD is the drag coef- 837. Ammonite Shell Variation and Streamlining 175

Table 2. Coefficients of variation of the geometric parameters at the middle of ruth whorl in the seventeen ammonites and Nautilus pompilius.

Species Geometric parameters W S D F Phyllocerataceae Hypophylloceras subramosu~ 4.79 5.00 7.44 5,19 Lytocerataceae Tetragonites glabrus 5.04 4.17 7.10 6.17 Tetragonites popetensis 4.48 5.00 7.37 5.13 Gaudryceras denseplicatum 1.53 3.73 7.33 5.98 Scaphitaceae Scaphites planus 15.34 8.18 15.59 12.45 Otoscaphites puerculus 8.03 4.31 9.88 10.14 Desmocerataceae Desmoceras japonicum 4.57 2.45 8.21 9.89 Tragodesmoceroides subcostatus 6.20 3.05 7.76 8.68 Damesites ainuanus 4.18 5.98 8.67 8.45 Damesites damesi 9.36 3,.57 5.72 4.28 Damesites semicostatus 5.73 3.37 7.18 7.55 Damesites sugata 7.53 6.95 7.62 3.33 Desmophyllites diphylloides 3.65 3.12 4.38 5.94 Neopuzosia ishikawai 3.36 5.42 9.99 6.60 Acanthocerataceae Subprionocyclus bravaisianus 13.66 23.40 8.33 8.78 Subprionocyclus neptuni 9.56 13.85 8.68 10.85 Reesidites minimus 7.97 12.31 7.12 11. 58 Nautilaceae Nautilus pompilius 4.01 3.87 18.62* 6.91 * Umblicus is covered by callus.

ficient (Chamberlain, 1976). If we consider that cephalopod adaptive design. The effect of F on the fluid density of seawater and shell size are CD was not demonstrated, but Chamberlain constant, the above equation is rewritten as (1980) suggested that within a suite of low S follows. shells, lower drag coefficients will occur when W and D are low, and F is high. Hydromechanically efficient cephalopod shells are high-shouldered, involute shells (Chamberlain, Assuming that DF is constant, V increases as CD 1981). Our adult shells of Hypophylloceras sub decreases. Thus, CD is an index of a shell's ramosum (W = 2.8, S = 0.6, D = 0.1, F = 0.4; hydrodynamic efficiency (Chamberlain, 1976). Figures 2-6A-B) and Placenticeras intercalare (W Chamberlain (1976, 1981) has demonstrated = 2.7, S =O.S,D = 0.1, F = 0.5; Figures 2-7 A-B) experimentally that at the same shell size CD are closely allied to this morphotype. The shell varies greatly with geometry. CD decreases as shape rather resembles that of N. pompilius, either W, D or S decrease. S causes the most whose drag coefficient (in 30° attitude) is 0.48 pronounced changes in CD, and the degree of (Chamberlain, 1976), and a similar or smaller shell compression should be a key factor in drag coefficient is indicated for the adult stage. 176 Kazushige TANABE and Yasunari SHIGETA

Seven desmoceratines also have relatively low D cate a wide variety of hydromechanical adapta and high F, but their S parameters are large (ca. tions among Cretaceous ammonites confirming 1.0), at least for the fourth and fifth whorls. the conclusion of previous authors (e.g. Raup In the adult stage (six whorls; 100 mm shell and Chamberlain, 1967; Ward, 1980, 1983; diameter) the whorls of Damesites semicostatus Chamberlain, 1981; Saunders and Swan, 1984) are narrowly umblicate and strongly compressed based on WeD analysis of many ammonites and (low S) with a prominent keel (see Figures nautiloids. According to Chamberlain's WeD 2-SA-B). This implies that the shell of this contour maps (1981, figs. 18-19), the range of species tends to be well streamlined. Shells of the the morphologic variation of the Ammonoidea three lytocerataceans (Figures 2-4A-B) may is much wider than that of the Nautiloidea. be compared with the model no. 26 of Chamber Furthermore, the range of geometric variation in lain (1976, table 1). The shells of the three the Mesozoic Ammonoidea is wider than in the collignoniceratids, Subprionocyclus bravaisianus, Paleozoic, and the main adaptive peak shifts S. neptuni and Reesidites minimus, are fairly larger D values. In our material, the Wand D compressed (S = 0.6-0.7 at fourth to fifth values of the seven desmoceratines, Hypophyllo whorls), but D is large. These Turonian collig ceras subramosum, and the well-streamlined noniceratids are very closely interrelated, and Placenticeras intercalare all plot near the adaptive possibly belong to a single clade (Matsumoto, peaks of the post-Jurassic Nautilida and the 1965; Reyment, 1975, 1982;Obataetal., 1979). Paleozoic Ammonoidea in the diagrams of The oldest species, the middle Turonian Sub Chamberlain (1981, figs. 18-19). Wand D data prionocyclus bravaisianus (Figures 2-2A-B), has of the other species resemble those of the com larger D and S than the latest, the late Turonian mon Jurassic-Cretaceous ammonites (Ward, 1980, R. minimus. The middle to late Turonian S. figs. 3-4; Chamberlain, 1981, fig. 19). Coarsely neptuni has intermediate values. In correspond ornamented planispiral ammonites with robust ence to this, surface ornament (tubercles and ribs, spines and tubercles became very common ribs) tends to weaken from S. bravaisianus to in the early Cretaceous, and during the middle to R. minimus. As Obata et al. (1979) have briefly late Cretaceous the number of heteromorph and mentioned, these trends of shell form and orna strongly ornate species comprised more than SO% mentation can be interpreted as adaptation to of the total species (Ward, 1981, 1983, 1986). increasing hydromechanical efficiency. Two Most of these morphotypes had larger D and S species of Yubariceras possess robust depressed parameters than streamlined shells (Figure 2; shells, with a pair of five rows of tubercles Ward, 1980). Ward (1981) speculated that the (Figures 2-lA-B). The large S (ca. 1.1) and small increase of coarsely ornamented species in the F (ca. 0.2) parameters and the coarse ornamenta Cretaceous was a defensive adaptation against tion suggest that both species were poor swim shell-crushing predators. In the Upper Cretaceous mers. The coiling parameters in the immature of Hokkaido, occurrences of coarsely ornated stage of scaphitids are similar to those of normal ammonites such as acanthoceratids and collig ly coiled species, but possess extremely large noniceratids are restricted to the nearshore, parameters W (ca. 4.0) and D (ca. O.S) at matu coarse-grained lithofacies (Tanabe, 1979). Com rity (Figures 2-3A-B). Their shell type cor plete preservation of the aperture and clustered responds to Chamberlain's (1976, Table 1) model occurrences at a single locality supports the auto no. 29, whose drag coefficient is 0.81. These chthonous origin of these fossil assemblages lines of evidence suggest that the scaphitids (Tanabe et al., 1978; Tanabe, 1979). This sup changed their way of life dUring ontogeny. In ports the predation interpretation. We believe all probability, they abandoned an active mode that most heavily ornamented ammonites were of life at maturity (Tanabe, 1977). poor swimmers, and that their possible mode of In conclusion, the results of this study indi- life was mobile benthic or nektobenthic. Con- 837. Ammonite Shell Variation and Streamlining 177 cerning the paleoecology of heteromorphs, biology, vol. 2, p. 316-331. opinions remain divided; some believe that they Hirano, H. (1975): Ontogenetic study of late Cretaceous were planktonic (Trueman, 1941; Ward, 1976, Gaudryceras tenuiliratum. Mem. Fac. Sci., Kyushu Univ., Ser. D., vol. 22, p. 165-192, pIs. 24-26. 1979; Ward and Westermann, 1977), other that --(1978): Phenotypic substitution of Gaudryceras (a they were benthic (Scott, 1940; Ziegler, 1967; Cretaceous ammonite). Trans. Proc. Palaeont. Soc. Tanabe et al., 1981). The former interpretation Japan, N. S., no. 109, p. 235-258, pIs. 33-35. is based mainly on the hydrostatic properties of --(1983): Revision of two vascoceratid ammonites the shells, and the latter on field occurrence. The from the Upper Cretaceous of Nigeria. Bull. Sci. Engineer. Res. Lab., Waseda Univ., no. 105, p. 44- mode of coilings and ornamentation in the 79, pIs. 1-5. Cretaceous heteromorphs are, however, quite Jordan, R. (1968): Zur Anatomie mesozoischer Am variable, and a single mode of life may not have moniten nach den Strukturelementen der Gehause applied to all groups. Heteromorphs with weakly lnnenwand. Beih. Geol. Jahrb., vol. 77, p. 1-64, ornamented and straight shells (e.g. Baculites) pIs. 1-10. Kant, R. (1977): Die lntegrationskonstante im allo probably could swim, while the presence of dif metrischen Wachstum, eine konstruktionsmorpho ferent coiling modes during ontogeny in some logischeAnalyse unter besonderer Beriicksichtigung nostoceratids (e.g. Eubostrychoceras and Mada des Ammonoideen-Gehauses. N. Jb. Geol. Paliiont. gascarites) suggest the loss of swimming ability, Abh., vol. 154, p. 263-289. even if they were neutrally buoyant (personal --and Scheuch, J. (1973): "Knickpunkte" im allome trischen Wachstum von Cephalopoden-Gehausen. communication with T. Okamoto). Further data Ibid., vol. 142, p. 97-114. on comparative morphology, anatomy and field --and -- (1980): Umstellungen irn Gehausebau occurrence are needed to clarify the above pro jungpaIaozoischer Ammonoideen Ein Arbeitskon blem. zept. N. Jb. Geol. Paliiont. Mh., 1980 (11), p. 673- 685. Kennedy, W. J. and Hancock, J. M. (1970): Ammonites Acknowledgments of the genus Acanthoceras from the Cenomanian of Rouen, France. Palaeontology, vol. 13, p. 462- We thank John Chamberlain Jr. and Bruce 490, pIs. 88-97. Saunders for critical reading of the first draft, --, Wright, C. W. and Hancock, J. M. (1980): Collig noniceratid ammonites from the Mid-Turonian of Peter Ward, Gerd Westermann and Roger Herwitt England and northern France. Ibid., vol. 23, for helpful discussions. We also appreciate Shozo p. 557-603, pIs. 62-77. Hayasaka and James Welch for providing shells Kullmann, J. and Kant, J. (1970): Wachstums-Xnderung of Nautilus and Placenticeras for this study. This en in der Ontogenese palaozoischer Ammonoideen. work was supported by a Grant-in-Aid for Lethaia, vol. 3, p. 397-412. -- and -- (1972): Absolutes und relatives Wachs Scientific Research from the Japanese Govern tum bei Ammonoideen. Ibid., vol. 5, p. 129-146. ment (no. 61480028 in 1986-1987). Kummel, B. and Lloyd, R. M. (1955): Experiments on relative streamlining of coiled cephalopod shells. 1. Paleont., vol. 29, p. 159-170. References cited Lehmann, U. (1976): Ammoniten. 171p. Ferdinand Enke, Stuttgart. Bayer, U. and McGhee G. R. Jr. (1984): Iterative evolu Matsumoto, T. (1942): Fundamentals in the Cretaceous tion of Middle Jurassic ammonite faunas. Lethaia, stratigraphy of Japan. Part I. Mem. Fac. Sci., vol. 17,p. 1-16. Kyushu Imp. Univ., Ser. D, vol. 1, p. 129-280, Chamberlain, J. A. Jr. (1976): Flow patterns and drag pIs. 5-20. coefficients of cephalopod shells. Palaeontology, --(1965): A monograph of the Collignoniceratidae vol. 19, p. 539-563. from Hokkaido, Part I. Ibid., vol. 16, p. 1-80, pIs. --(1981): Hydromechanical design of fossil cephalo 1-18. pods. p. 289-336. In: House, M. R. & Senior, J. R. Mutvei, H. (1964): Remarks on the anatomy of recent (eds.): The Ammonoidea. Academic Press, London and fossil Cephalopoda. Stockh. Contr. Geol., vol. & New York. 11, p. 79-102. --and Westermann, G. E. G. (1976): Hydrodynamic --and Reyment, R. A. (1973): Buoyancy control properties of cephalopod shell ornament. Paleo· and siphuncle function in ammonoids. Palaeonto· 178 Kazushige TANABE and Yasunari SHIGETA

logy, vol. 16, p. 623-636. the habitat of Nautilus pompilius in the environs of Obata, I., Tanabe, K. and Futakami, M. (1979): Onto Viti Lebu, Fiji. Kagoshima Univ. Res. Center for S. geny and variation in Subprionocyclus neptuni, an Pacific, Occasional Paps., no. 4. Upper Cretaceous collignoniceratid ammonite. Bull. --, Hirano, H., Matsumoto, T. and Miyata, Y. (1977): Natn. Sci. Mus., Ser. C (Geol.), vol. 5, p. 51-88, Stratigraphy of the Upper Cretaceous deposits in pIs. 1-5. the Obira area, northwestern Hokkaido. Sci. Rep. Raup, D. M. (1966): Geometric analysis of shell coiling: Dept. Geol. Kyushu Univ., vol. 12, p. 181-202 general problems. J. Paleont., vol. 40, p. 1178- (in Japanese with English abstract). 1190. --, Obata, I. and Futakami M. (1978): Analysis of --(1967): Geometric analysis of shell coiling: coiling ammonoid assemblages in the Upper Turonian of in ammonoids. Ibid., vol. 41, p. 43-65. the Manji area, central Hokkaido. Bull. Natn. Sci. --and Chamberlain, J. A. Jr. (1967): Equations for Mus., Ser. C (Geol.)., vol. 4, p. 37-62, pI. 1. volume and center of gravity in ammonoid shells. --, -- and -- (1981): Early shell mor Ibid., vol. 41, p. 566-574. phology in some Upper Cretaceous heteromorph Reeside, J. B. Jr. and Cobban, W. A. (1960): Studies of ammonites. Trans. Proc. Palaeont. Soc. Japan, N. the Mowry Shale (Cretaceous) and contemporary S., no. 124, p. 215-234, pIs. 35-38. formations in the United States and Canada. Prof Trueman, A. E. (1941): The ammonite body-chamber, Pap., U. S. Geol. Surv., no. 355, p. 1-126, pIs. with special reference to the buoyancy and mode 1-58. of life of the living ammonites. Q. J. Geol. Soc. Reyment, R. A. (1975): Analysis of a generic level tran Lond., vol. 96, p. 339-383. sition in Cretaceous ammonites. Evolution, vol. 28, Ward, P. D. (1976): Upper Cretaceous ammonites p.665-676. (Santonian-Campanian) from Orcas Island, Washing --(1982): Size and shape variation in some Japanese ton. J. Paleont., vol. 22, p. 609-630, pI. 1. Upper Turonian (Cretaceous) ammonites. Stockh. --(1979): Functional morphology of Cretaceous Contr. Geol., vol. 37, p. 201-214. helically-coiled ammonite shells. Paleobiology, vol. Saunders, W. B. and Swan, A. R. H. (1984): Morphology 5, p. 415-422. and morphologic diversity of mid-Carboniferous --(1980): Comparative shell shape distributions in (Namurian) ammonoids in time and space. Paleo Jurassic-Cretaceous ammonites and Jurassic biology, vol. 10, p. 195-228. Tertiary nautiloids. Ibid., vol. 6, p. 32-43. Schmidt, H. (1930): Uber die Bewegungsweise der --(1981): Shell sculpture as a defensive adaptation in Schalencephalopoden. Paliiont. Z., vol. 12, p. 194- ammonoids. Ibid., vol. 7, p. 96-100. 208. --(1983): The extinction of the ammonites. Sci. Scott, G. (1940): Paleoecological factors controlling the Amer., vol. 249, p. 136-147. distribution and mode of life of Cretaceous am --(1986): Cretaceous ammonite shell shapes. Mala monoids in the Texas area. J. Paleont., vol. 14, p. cologia, vol. 27, p. 3-28. 299-323. --and Westermann, G. E. G. (1977): First occurrence, Stiirmer, W. (1970): Soft parts of cephalopods and systematics, and functional morphology of trilobites: some surprising results of X-ray ex Nipponites (Cretaceous Lytoceratina) from the aminations of Devonian slates. Science, vol. 170, Americas. J. Paleont., vol. 51, p. 367-372, pI. 3. p.1300-1302. Westermann, G. E. G. (1966): Covariation and taxo Tanabe, K. (1977): Functional evolution of Otoscaphites nomy of the Jurassic ammonite Sonninia adicra puerculus (limbo) and Scaphites planus (Yabe), (Waagen). N. Jb. Geol. Paliiont. Abh., vol. 4, p. Upper Cretaceous ammonites. Mem. Fac. Sci., 389-412. Kyushu Univ., Ser. D, vol. 23, p. 367-407, pis. 62-64. --(1971): Form, structure and function of shell and siphuncle in coiled Mesozoic ammonoids. Life Sci. --(1979): Palaeoecological analysis of ammonoid Contr., Royal Ontario Mus., no. 78, p. 1-39. assemblages in the Turonian Scaphites facies of Ziegler, B. (1967): Ammoniten-Okologie am Beispiel Hokkaido, Japan. Palaeontology, vol. 609-630. des Oberjura. Geol. Rundschau, vol. 56, p. 439- --(1985): Record of trapping experiment. p. 10-17. 464. In: Hayasaka, S. (ed.): Marine ecological studies on 837. Ammonite Shell Variation and Streamlining 179

B!IE*c 7 :/ -'f: T l' r ~~O)pJ(;~~;:ff? m1:ifj~t~ t i:itE~)l'};* : ~tW)gP.10)13tWl B!IE*c 7:/ -'f: T l' r 17~0).['llfJ*~ ffl~'-C, RlI:~~;:ff? m1:ifj/~ ';7.>1 - 31 O)~ft ~ J;tf,l~W Lt-::o ~~-;j Lt-::/~ '7 .>1-311';1:, Raup~;:J:-?-Cmp~~ht-::~:\ij)Mi* (W), ~:\i~~* (D), ~:\iO)i\1Ii~~;:M-tG$i 0)J;t (S), fJI~iIiiO);ffiMB%rli: (F) 0)4"?"('~Go ::'hi?O)?t:>, D, S:loJ:rfFli, XlJJtIl~;:li~ rl3,-e*~tJ:~'iJ~, RlI::llH;:ff-?-C*~ <~tJ:G J:? ~;:tJ:Go RlI:~JtIl~;:li, ~iIii~Uf!iO)z U'7 -1 p -!! '7 /'~f4~T /, -'f: -!! '7 /'~f40)~-eli S ~ nli/j' ~ <, iJ>"?.f:h i? O)~P'J~~:I: t Ij' ~ ~ '0 ~ ~;:, ~iIii\lUf!i0)~U'7 t;:/ r -!!'7/'~f4~~-m-~0)/,t;7 -1 T/'f4O)~"('li, S, Dli*~ <, .:thi?O)~P'J~~:l:li*~~'o tt*O)lmf4i:~~O)*6*"('li, S, Dlilm~3l1J*~;:*~ <~-3:- L, .f: hi?O)lj' ~ ~,:ljZm~O)Mli/j, ~ ~ 'mt.Jfifi~~~"?::' c iJ~:hiJ>-? -C~ 'Go -h5SiHilj~JliHi, lm~ 3l1J*~;:li "? l' T /,"(. tlm11t~~;:M-t G IiOmI t L -c)l'};*(t-J"(' ~ -? t-:: t:;,lf;:t i? h Go tJJ: 0)::' t iJ' i?, B!lEe7:/-'f:T1'rMK.~i?hGm1:ifjO)*~~~~~,~.~~~.~tM$Lk~$ifj ~~&:I!!k: L -C~'G tJt~~hGo .fjjJJ$-RlI: . ~ffimRll: Trans. Proc. Palaeont. Soc. Japan, N. S., No. 147, pp. 180-194,12 Figs., October 30,1987

838. LIFE HABIT AND RELATIVE GROWm OF SOME LAQUEID BRACHIOPODS FROM JAPAN

KAZUYOSHI ENDO Geological Institute, Faculty of Science, University of Tokyo, Tokyo 113, Japan

Abstract. Japanese Cenozoic laqueid brachiopods generally show two allometric trends. One is the ontogenetic increase in valve convexity versus valve length, and the other is the ontogenetic decrease in valve width versus valve length. To examine the causation of these morphologic changes, the general morphology, life habit, and allometric relationships of some metric characters were investigated in the Recent samples of Laqueus rubellus (Sowerby). The following are three explanations for the relative increase of shell convexity: 1) efficient secre tion of shell material, 2) strengthening the shells, and 3) providing larger space for adult gonad. Among them, the third explanation seems most appropriate at least in L. rubellus, because of a diphasic allometric relationship between valve convexity and valve length: while valve convexity is positively allometric to valve length in adults, they are isometrically related in juveniles.

Introduction hitherto proposed. Raup and Stanley (1978) suggested that the allometry in E. wattsi may In many cases, post-Paleozoic brachiopods be size-related, though how size relates to the have simple elliptical outlines and show allomet change of the shape was not mentioned. McGhee ric growth during ontogeny. Brachiopod shells (1980) interpreted the ontogenetic increase in often show significant. deviation from ideal valve convexity in many biconvex brachiopods as logarithmic spirals (Rudwick, 1959; McGhee, obtaining maximum internal volume by mini 1980). McGhee (1980) examined 324 genera mum shell surface area. Maximum internal shell of four orders of articulate brachiopods, and volume is favorable to house intricated lopho showed that well over a half of them changes ph ore , whereas minimum shell surface area is their whorl expansion rates during ontogeny. advantageous because it costs least metabolic An overwhelming trend is the relative increase energy to secrete shells. of valve convexity with growth. Here, I propose several explanations for the Brachiopods change the form of the com allometric changes observed in the living brachio missure during ontogeny as well as their general pod, L. rubellus. I suggest that these explanations shape. For example, Raup and Stanley (1978) may also apply to some cases of allometric cited relative growth in a Carboniferous brachio growth in fossil brachiopods. pod, Ectochorisites wattsi, which alters the com The following abbreviations are used in this missure form ontogenetically from the shape that study for the metric characters and the statistical is wider than long to the shape that is longer than values. L: length of the ventral valve, W: width of wide. the shell, T: thickness of the articulated valves, Causation of the allometry in the brachiopods F: diameter of the foramen, Wt: shell weight, is not decisive, but some interpretations were Lm: length of the median septum, S1: surface area of the lophophore, A: surface area of the Received' July 30, 1987; read January 31, 1987 at shell, V: inner volume of the shell, 0:: regression Shizuoka University.

180 838. Relative Growth of Laqueid Brachiopods 181 coefficient, slope of allometry, K: statistical Juvenile morphology of Laqueus rubellus value for discrimination of allometry (Hayami and Matsukuma, 1971). The juvenile shell is distinguished from the adult shell by the poorly developed gonad and General morphology of laqueid species smaller size. The figured specimen (Figures 1-4- 6, L = 11.95 mm) is certainly juvenile because it The articulate superfamily Terebratellacea, has no gonads. characterized by having long-looped brllchidium, The shell morphology of the juveniles is are classified into several families by different different from that of the adults. Lateral sides mode of development of the loop. Hatai (1965) and anterior margin in dorsal view are broadly defined Laqueidae, one of the terebratellacean rounded and forming almost circular outline. families, as possessing loops with interconnecting The valves are nearly equally convex, but both bands which unite ascending and decending valves are compressed or less convex compared branches. Laqueidae was redefined by Richardson to that of the adults. Although the absolute (1975) as "Loop passing through axial, annular, foramen size is smaller than that of the adults, and haptoid phases to a bilacunar loop pattern; relative foramen size to the shell length is larger bilacunar pattern may be the adult loop pattern than that of the adults. The shell is always fresh or be followed either by bilateral and lateroverti and it is so thin that the lophophore and other cal phases or by trabecular and teloform phases." soft parts are seen through from the exterior. The loop pattern in the specimens of ca. Adult morphology of Laqueus rubellus 10 mm in shell length is already bilateral. The earlier loop development phase, namely bilacu Figures 1-1-3 show an adult shell of L. nar, is observed in the specimens of 7 mm long. rubellus. Figure 2 shows gross morphology, The still earlier phase, namely haptoid, is ob measurements, and internal morphology of the served in the specimens less than 4 mm in length. dorsal valve of adult L. rubellus. The shell is The phase in lophophore pattern of the figured so thin (less than 0.5 mm) and translucent except specimen (UMUT RB18186b) is already plecto for the cardinalia that the gonad can be seen lophous. In the specimens with a bilacunar loop through the shell. The shell is mostly yellowish pattern, the lophophore is plectolophous, while red, with deeper tinges at concentric lines. The it is zygolophous in the specimens with a haptoid intervals of the growth lines become denser near loop pattern. the margin. An adult L. rubellus has a bilateral brachidium (Figure 2). Morphologic features of other species The gonad sticks on the inner surface of both ventral and dorsal valves, being lapped in mem Eight laqueid species treated here show branes. The males and females can be easily dis rather similar biconvex form of smooth shell tinguished by binocular observation of the surface (Figure 1). Every species, except for gonads. Two types of texture are observed, one Laqueus blanfordi and L. quadratus, thicken the is the aggregated small particles, the other is a posterior part of the shell during growth. The lump of smooth appearance. SEM observation adult individual of L. blanfordi has a pedicle as of gonads confirms that the former and the latter long as the length of the shell. However, in Picto are of females and males respectively (Figure 3). thyris picta and P. sp., the pedicle is so short that The egg is about 70 Ilm in diameter, whereas the in most case the shell is attached directly to the head of the sperm is about 1 Ilm in diameter. substrate. The foramen of Kikaithyris hanzawai Sexual dimorphism was not observed at least is so minute that the pedicle may have been for the gross morphology and size of the shells. atrophied in the adult phase (Table 1). 182 Kazuyoshi ENDO 838. Relative Growth of Laqueid Brachiopods 183

A B c POSTERIOR

Figure 2. Gross morphology, measurements and Figure 3. SEM photographs of the gonad of L. internal morphology of the dorsal valve of Laqueus rubellus [Sample Rk (104), April 8, 1986]. 1, Ova, rubellus. A: dorsal v.iew; B: right lateral view; C: internal UMUT RB18186c, scale bar indicates 100J,lm ; 2, Sperm, view of the dorsal valve showing the bilateral loop and UMUT RB1 8186d, scale bar indicates 10 J,lm. the configuration of the lophophore (half ommitted). L: length of the ventral valve; W: width of the ventral or the dorsal valve; T: thickness of the articulated valves; Life habit of laqueid species Lm: length of the median septum; 1: crura; 2: crural process; 3: median septum; 4: connecting band; S: in Ecology of Laqueus rubellus terconnecting band; 6: transverse band; 7: descending Hatai (1940) compiled the data on the Recent branch; 8: ascending branch. brachiopods collected by the cruises of R/V

Table 1. Some adult morphologic characters in eight laqueid species examined.

LOOP MINUTE SPECIES SAMPLE WEIGH PEDICLE MAX. PATTERN DOWN FORAMEN L(mm) Laqueus rubellus Jz(L), Rk • medium 29.55 l. blanfordi Ot long 28.35

L. quadratus Na, Hi bilateral medium 21.75 l. sp.1 Ts (L) • medium 21.45 l. sp .2 Sw • - 21. 10 Pictothyris picta Jz(p), Rk(P) short 31.75 latero - • P. sp. Ts(P) vertical • short 18.40 Kikaithyris 'hanzawai Wa •• - • 40.20

~ Figure 1. Overall shell morphology of eight laqueid brachiopods. (All figures x l , scale bar indicates 1 cm.) 1-3, Laqueus rubel/us (Sowerby), adult specimen, off Jyogashima, Sagami Bay, Sample Rk (82), UMUT RB18186a; 4-6, L. rubel/us, juvenile specimen, off Jyogashima, Sagami Bay, Sample Rk (17), UMUT RB1 8186b; 7-9, L. blanfordi (Dunker), Otsuchi Bay , Sample Ot (2), UMUT RB18188a; 10-12, L. quadratus Yabe and Hatai, off Hinomisaki, Kii Channel, Sample Hi, UMUT RB18190a; l3-1S,L. sp. 1, off Tsukumi, Bungo Channel, Sam ple Ts (L), UMUT RB18191a; 16-18, L. sp. 2, Sawane Formation, Sado Island, Sample Sw, UMUT CB18192a; 19-21, Pietothyns pieta (Dillwyn), off Jyogashima, Sagami Bay, Sample Rk (P), UMUT RB18194a; 22-24, P. sp., off Tsukumi, Bungo Channel, Sample Ts (P), UMUT RB1819Sa; 2S-27, Kikaithyris hanzawai (Yabe), Wan Formation, Kikai Island, Sample Wa , UMUT CB18196a. 184 Kazuyoshi ENDO

Soyo I. His collections from 81 stations show pebbles or shell fragments. Some rock fragments that Laqueus rubellus is found from 30 m water were incrusted both by individuals of L. rubellus depth to depths in excess of 499 meters. Most and P. picta. The diameter of the substrate parti specimens were collected on sand or gravel cles falls in the range of 5-15 mm. During bottoms and bottom temperatures range from growth the substrate for these brachiopods be 2.0°C to 23°C ex = 15-20°C). Though Hatai comes relatively small, and it would be insuffi (1940) failed to describe whether the individuals cient to support the whole shell. In addition, the were living or not, the major habitats of L. shell weight shows an allometric increase during rubellus became clear: sandy or coarser sub growth mainly due to the thickening of the strata on the continental shelves and the upper posterior part of the shell (Figure 4). Therefore, most part of slope under the influence of warm the adult individuals of L. rubellus from Sagami ocean currents. Bay must be free-lying on the sea bottom. Living specimens of L. rubellus and Pictothyris Many brachiopods are known to reorient to picta were repeatedly dredged by R/V Rinkai water currents (LaBarbera, 1977,1978; Richard of the Misaki Marine Biological Station of the son, 1981 b). Juvenile form of L. rubellus may University of Tokyo in various seasons at the have the ability to reorient to water current be depths of 85-90 m from sandy bottoms near the cause of the relatively stable attachment, while edge of the continental shelf of eastern Sagami the adults may not have this ability because of Bay, about 2 km west of the western end of their relatively small-sized substrates. Jyogashima-Islet. A total of 780 individuals of The feeding and the excretion of faeces occur L. rubellus were collected and 35 of P. picta in through filtering system of the lophophore 17 samples. (Rudwick, 1970). Adult individuals of L. rubellus Most of the living individuals of L. rubellus from Sagami Bay were kept in aquaria with con were dredged with the pedicle attached to tinuous circulation of fresh seawater for two A B 10 10 N = 21 N = 32 r =0.996 r = 0.991 a,= 3.154 a,=3.393 _1 ...... 3 3 o • 0.1 0.1

0.01 ~"",,"---'-.L..-L--I..-.J'-__--L_--,_-I 0.01 '-----'-----L---4.---L--J..-L-L-___-'-_--.. 4 10 20 30 40 3 10 20 30 L(mm) L(mm)

Figure 4. Double logarithmic plots and regression line with the reduced major axis of shell length (L) vs. shell weight (Wt). A: Kikaithyris hanzawai (Sample Wa); B: Laqueus rubellus [Sample Rk (80)]. Shell section along the plane of symmetry is also shown in each figure. Scale bar indicates 1 em. This figure shows positive allometry of Wt to L owing to the differential thickening of the posterior part of the shell. 838. Relative Growth of Laqueid Brachiopods 185 days. All the individuals gaped slightly (the angle lying life habit. Individuals of Pictothyris picta of gape is about 5_10°), and fully extend the from the same stations of Sagami Bar [Sample filaments of the lophophore, which trembled Rk (P)] also attached themselves to small un weakly. They qUickly closed the valves periodi stable particles. Such free-lying mode of life has cally without any stimulation at intervals of not been described in extant articulate brachio several minutes, and after a while, they gradually pods except for Richardson (1981a). Permanent opened the valves. When touched, they quickly attachment to hard stable substrate seems more closed the valves. common in extant articulate brachiopods. To observe the filtering system more in detail, Individuals of Pictothyris sp. [Sample Ts (P)] the valves of L. rubellus were separated after attach themselves to pebbles of moderate size two days' rearing in aquaria. The individuals ranging three to five times as large as the adult were still alive after the separation of two valves. shells. This relative size of adhering material The observed movement of the filaments was suggests an intermediate mode of life between contrary to expectations. Each filament of the free-lYing and permanently attached. Specimens lophophore moved somewhat individually and of Laqueus blanfordi (Sample Ot) were collected flexibly, though the movement of one filament in a fishing net with the individuals attached to a accompanies the movement of the neighboring tangled rope of about 1. 5 cm in diameter. From filament. The mode of movement resembles the this mode of occurrence, an attached life is motion of the tentacles of a sea anemone. The strongly suggested for this species, although expected conformation of filaments, that the the type of substrate may be very different in filaments fully extended with the tips of them different samples. along the commissure, was also observed, but this Kikaithyris hanzawai (Sample Wa), a Plio state did not last for more than one minute. Pleistocene fossil species from Ryukyu Islands When stimulated by a needle, all the filaments and Formosa, shows the characteristic shell were observed to recoil. These unexpected morphology suggesting a reclining mode of life. motions may be partly due to the separation of The shell of K. hanzawai is fairly large. The the valves, but it suggests the ability of the fila dorsal view is shouldered in comparison with L. ments to move flexibly. Similar movements of the filaments in separated valves in other tere bratellacean species were reported by Thayer Al.rubellus N=Jl 3 oP.pieta N=JO (1986) who suggested that the movements are E a mechanism of rejecting nonfood particles. E • K. hanzawai N = JJ As listed below, numerous living individuals LL of L. rubellus were collected in various seasons 2 from almost same station: (J) May 25 and 26, 1978, (2) October 4 and 5,1979, (3) March 11, 1982, (4) July 27, 1982, (5) Aug. 3, 1983, (6) July 10, 1985, (7) April 8, 1986, and (8) April 28 and 30, 1987. Every sample includes adult specimens with OL---~----~--~----~~ both moderately and poorly developed gonads. o 10 20 30 40 There is no seasonality of maximum gonad L(mm) development, so the time of reproduction is still Figure 5. Scatter plots of FversusL in L. rubellus unknown. [Sample Rk (80)), Pictothyris picta [Sample Rk (P)), and Kikaithyris hanzawai (Sample Wa). The margin of the foramen of L. rubellus and P. picta is resorbed and Mode of life of other species the diameter becomes large with growth. However, in K. hanzawai, the margin of the foramen is scarcely Laqueus rubellus possesses a secondarily free- resorbed. 186 Kazuyoshi ENDO rubellus (Figure 1-25). It has a strongly incurved function between Land W, and Land T. The beak (Figure 1-26) and a foramen which is regression line was calculated using the reduced unusually minute for its large shell (Figure 5, major axis method (Imbrie, 1956), in which the Figure 1-25). The shell is thin (less than 0.5 mm) slope (a) of allometry in a log-log plot (regression except for the thick posterior part of the shell. coefficient) is given as: The weight of the shell is positively allometric to the cube of length owing to the differential a=~ Sx ' thickening of the shell in posterior region (Figure 4). These morphologic features indicate a free where Sx and Sy are the standard deviations of lying mode of life in this species; the pedicle of x and y, respectively. The regression coefficients K. hanzawai must have been degenerated with are tested against the null hypothesis, growth, because the size of the foramen deter mines the diameter of the pedicle. Moreover, Ho : a = 1, K =----s;- a- 1 ( Hayami an d the incurved beak is unfavorable to hold a Matsukuma, 1971), pedicle because it points to the dorsal valve where K has a normal distribution, and Sa is (Figure 1-26). Judging from the similar outline the standard error of the regression coefficient. to L. rubel/us in the early stage, K. hanzawai Discrimination between isometry and allo probably changes the mode of life from an at metry is arbitrarily defined at the confidence tached life habit to a completely free-lying one level of 95% (Hay ami and Matsukuma, 1971): without a functioning pedicle during ontogeny. The value of Kover 1.96 means the y-variable In modern seas only one species, Neothyris is positively allometric to the x-variable; and lentieularis, is certainly free-lYing without negatively allometric when K < -1.96; if the pedicle attachment (Rudwick, 1970; Richardson, value of K is between 1.96 and -1.96, the null 1981a). hypothesis (isometry) cannot be rejected. Laqueus quadratus (Sample Hi) does not Figure 6 shows an example of bivariate possess thickening of the posterior part of the analysis on the L-W relation and the L-T relation. shell. In a strong bottom current, a free-lYing The reduced major axes on double logarithmic state of such light shells would be unstable and scatter diagrams indicate that W is negatively disadvantageous. Therefore, attached mode of allometric to L, and that T is positively allomet life is suggested for this species as in L. blanfordi. ric to L. Individuals of Laqueus sp.1 [Sample Ts (L)] and Figure 7 shows another example of bivariate Laqueus sp.2 (Sample Sw) thicken their posterior analysis on the L-W and L-T relationships. In part of the shells. This character, however, does this sample, the males and the females are ana not necessarily mean a free-lying mode of life lyzed separately. In both males and females, because the equivocal species Pietothyris sp. W grows significantly negative allometric to L, [Sample Ts (P)] exhibits similar features. and T grows positive allometric to L. The dif ference of regression coefficients is not signifi Relative growth cant between the males and the females at 95% confidence level. The shell form of Laqueus rubellus changes Table 2 lists the results of the average relative during ontogeny from a circular outline in dorsal growth analyses of T vs. L and of W vs. L on 8 view to an elongate oval. The shell also becomes samples of 7 species. Double logarithmic scatter more strongly convex in the adult stage. In order diagrams for P. pieta and K. hanzawai are shown to quantify this allometric change, bivariate in Figure 8 and Figure 9 respectively. analyses of Land W as well as Land T were In all species examined, T shows a more or performed. less positive allometry to L. Except for L. The bivariate analysis assumes a simple power 838. Relative Growth of Laqueid Brachiopods 187

A B _ 30 ..------,_30 ,------, E E E E N = 32 -N = 32 3 1-20 20 r = 0.989 r = 0,989 W= 1.535 L0.789 T = 0.351 L1.120 ~. 10 . -'

2~--'--"""'--...... '--'- ...... ------'-----'--..L....J 10 20 30 3 10 20 30 4!J L(mm) L(mm)

Figure 6. Double logarithmic allometric relationship between Land W (A) and between Land T (B) in L. rubellus [Sample Rk (80)]. Regression line with the reduced major axis is indicated in the this figure.

A B 4!J 20 eMALE eMALE E N=26 N= 26 E '=0.935 E ,= 0.980 «= 0.770 E <1= 1.355 3 30 OFEMALE OFEMALE I- N= 21 N=21 ,= 0.896 '=0.931 '" = 0.825 <1=1.317

20 10

20 30 40 20 30 40 L(mm) L (mm)

Figure 7. Double logarithmic allometric relationship between Land W (A) and between Land T (B) in L. rubellus [Sample Rk (13)]. Males and females are separately treated. Regression line with the reduced major axis is indicated in this figure. 188 Kazuyoshi ENDO

Table 2. Allometric relationship between Land W and between L and T in eight samples of seven species. N: number of individuals; a: regression coefficient, slope of reduced major axis in the double logarithmic scatter diagram; (1: standard error of a; r: correlation coefficient; K: statistical value for discrimination of allometry (Hayami and Matsukuma, 1971).

species sample N L - W L - T OC 0- r K ex (f r K Laqueus rubellus Rk(13) 47 0.786 0.043 0.926 - 4.96 1.345 0.049 0.968 7.04 L. rubellus Rk(8o) 32 0.789 0.021 0.989 -10.18 1.120 0.030 0.988 4.02 L. blanfordi Ot(1,2) 27 1.004 0.014 0.997 0.30 1.206 0.015 0.998 13.76 L. sp. 1 Ts(U 46 0.801 0.059 0.864 - 3.34 1.496 0.102 0.887 4.86 L. sp. 2 Sw 44 0.923 0.025 0.984 - 2.87 1.176 0.036 0.979 4.84 Pietothyris pieta Rk(P) 36 0.824 0.033 0.971 - 5.34 1.229 0.047 0.973 4.85 P.sp. Ts(P) 43 0.867 0.024 0.983 - 5.44 1.178 0.033 0.983 5.39 Kikaithyris hanzawai Wa 33 0.940 0.013 0.997 - 7.05 1.091 0.014 0.996 5.51

A 8 40 20

E N = 36 E N =36 E E .7 330 r =0.971 I- r = 0.973 W= 1.413 L0.B24 T = 0.238 L,·229 I. . !~ 20 10 .'./'

5 20 30 40 10 20 30 40 Umm) Umm)

Figure 8. Double logarithmic allometric relationship between Land W (A) and between Land T (B) in Pietothyris pieta [Sample Rk (P)). Regression line with the reduced major axis is indicated in this figure. 838. Relative Growth of Laqueid Brachiopods 189 A B 50~------~ 50~------"E40 ~40 N=33 E N = 33 ;:: 30 3 30 r=0.997 r = 0.996 W= 1.095 LO. 940 / 20 T = 0.380 LtOB9 .. 20 / 10 10 / •

10 20 30 40 50 10 20 30 40 50 Umm) l(mm)

Figure 9. Double logarithmic allometric relationship between Land W (A) and between Land T (B) in Kikaithyris hanzawai (Sample Wa). Regression line with the reduced major axis is indicated in this fIgure. blanfordi, the slope of allometry for W vs. L is shells and pebbles, all of which are smaller in size negatively allometric, and this indicates the than the animal, as is the case with L. rubellus decrease in the ratio WIL with growth. from Sagami Bay. In such free-lying species, the post-larval Interpretation of ontogenetic increase in juveniles must attach themselves to some objects. The attached object may become unnecessary as valve convexity living animals grow larger. It is at present unclear Raup and Stanley (1978) stated that "ontoge how the above change in mode of life relates tc netic change in shape accompanies two other the change in valve convexity or in commissure sorts of change; i.e. change in mode of life form. One possible explanation is hydrodynamic and change in size." The change of shell shape stability of the shell. Possibly, free-lYing brachio with the change in mode of life is examined as pods are selected for hydrodynamic stability. the cause of ontogenetic increase in valve con Allometric increase in valve weight, as already vexity. The mode of life in many living articulate stated, may have a role for this purpose. How brachiopods has been assumed to be rather ever, Alexander (1984) finds that hydrodynamic monotonous; except for the larval stage, they stability is highest in dorsal-ventrally compressed permanently attached to hard substrate, feeding and concavo-convex species. Thus, allometric on the suspension matter through the lopho growth in laqueid brachiopods may not be pro phore. duced by selection for hydrodynamic stability. In such an attached species, significant change Ontogenetic increase in valve convexity was in mode of life may not occur. However, some observed in alliaqueid species from Japan includ instances of secondary free-lying mode of life are ing both the attached and free-lying species. For observed in modern articulate species by Richard example, L. blanford; attached rope shows posi son (1981 a, 1981 b). Free-lYing species some tive allometry of T relative to L. The shift from times retain attached nature to fragments of the attached to the free-lying does not explain 190 Kazuyoshi ENDO

the change in shell form. Table 3 shows the results of regression ana I believe that most allometric growth can be lyses on the relationship among 81, A, V and explained by size increase. McGhee (1980) Lm. 81 does not increase as the cube of Lm assumed that the metabolic requirement of a (O! = 0.748), but it is positively allometric to brachiopod is a function of volume of the soft the square of Lm at 95% confidence level. tissues and that the capacity of the lophophore As is expected, the approximate surface area of to meet these requirements is a function of its the shell decreases with growth, relative to a fIlamental area, as expressed by the relative in linear dimension of the soft tissues (Figure 10). crease in the surface area of the lophophore. Since the surface area of the shell is two dimen Therefore, the inner volume of the shell increases sional, the level of isometry in the relation in ontogeny to house the allometrically growing between Lm2 and A is at O! = 1. The actual lophophore. The economics of shell secretion growth of A to Lm2 indicates negative allometry dictates that a spherical surface is most efficient (O! = 0.935). In spite of the ontogenetic change to attain the greatest inner volume. Because of in the shell form, V increases isometrically the accretionary growth of two coiling tubes in articulation, truely spherical form is not attaina Table 3. Results of bivariate analyses on Sl. ble. Therefore, brachiopods grow allometrically A. VandLm. [SampleRk (80)). For to increase shell convexity during ontogeny by abbreviations see explanation in decreasing the whorl expansion rate. Table 2. Surface area of the lophophore (81), the inner x y N ~ r K volume of the shell (V), and the surface area of Lm~SI 32 1.123 0.962 2.26 the shell (A) were measured to analyze the area 3 volume relationship discussed by McGhee (1980). Lm - SI 32 0.748 0.962 -6.97 All measurements were made on the sample Rk Lm2- A 32 0.935 0.985 -2.27 (80) of L. rubellus. Lm3- V 24 0.986 0.982 -0.36 The surface area of the lophophore was cal culated through the following procedure. The excised lophophore was cut into pieces and ~~------, 40 photographed at fixed magnification. The print -l) N =32 N ed fragments were cut out along the margins, E r = 0.985 and the cut pieces of the printing paper were .s20 weighed. Lastly the weight was converted into « the area. The inner volume was estimated by 10 filling both valves with #800 carborundum and the weight of the carborundum was converted into inner volume. The surface area of the shell was calculated on an assumption that an ellipsoid approximates the outline of L. nt.bellus. Because the length of the median septum A= 5.250 (Lm2)0935 (Lm, see Figure 2) roughly represents a linear dimension of the soft tissues and because the soft tissues occupy the space between the anterior 4 10 200 and posterior edges of the median septum near the hinge line, these three measurements (81, A, Figure 10. Double logarithmic allometric relation V) were compared to Lm. Lm was measured ship between the square of Lm and A in L. rubellus under the profIle projector with a digital micro [Sample Rk (80)). Regression line with the reduced meter. major axis is indicated in this figure. 838. Relative Growth of Laqueid Brachiopods 191 relative to Lm 3 • The plot of Lm 3 against V Table 4. Dried weight of each soft tissue in three speci shows a regression coefficient of 0.986 and mens of L. rubellus [Sample Rk (100)). indicates near isometry. SPl:CIMEN 1 2 3 The results obtained seem to consistent with BODY PARTS WT. % WT. % WT. % the hypothesis of McG!lee (1980) as a whole. ----- GONAD 11.94 25.9 16.68 33.1 13.50 30.2 The surface area of the lophophore ontogeneti MANTlE & PERIOSTRACUM 9.11 19.8 14.08 28.0 8.19 18.3 cally increases over the square of the length, PEDICLE & MUSClE 10.08 21.9 8.17 16.2 11.64 26.0 while the surface area of the shell ontogeneti 15.3 3.89 7.7 3.40 7.6 cally decreases below it. However, contrary to DIGESTIVE SYSTEM 7.03 expectations, the surface area of the lophophore LOPHOPHORE 7.87 17.1 7.53 15.0 7.97 17.8 does not increase as much as the cube of the TOTAL 46.03 100.0 50.35 100.0 44.70 99.9 - length of the body. The inner volume of the x 10 3g shell increases nearly isometrically versus the cube of the length of the soft part. These facts using specimens in the three samples Rk (13), indicate that the capacity to meet the metabolic Rk (17), and Rk (80). requirement may not be a function of the fila Figure ll-A indicates that T and L are posi mental area of the lophophore, but a function tively allometric in adults, but are isometrically of the inner volume of the shell, which the related in juveniles. The regression coefficient of lophophore effectively occupies. the adults is 1.342, the K-value against the null Another possible size-related explanation is hypothesis of O! = 1 is 11.29. On the other hand, that brachiopods become more convex to in in the juveniles the regression coefficient value is crease mechanical strength of the valves. The 0.987 (K = -0.53). test of adult laqueid brachiopods is thin except The K-value against the null hypothesis of for the cardinalial (posterior) part. The test homogeneity of regression coefficients between thickness does not increase as the shell grows. juveniles and the adults is -9.09. The regression This indicates the gradual decrease of the relative coefficients between mature and immature strength of the shell with growth, and, therefore, samples are different at the 95% level, and the the reinforcement by shell form is considered to relationship between Land T is considered to be be required. The predator of the brachiopods is diphasic allometry. T increases isometrically to unknown, but non-fatal injuries in some speci L during the early growth stage, and T increases mens of L. rubellus from Sagami Bay suggest positively allometric ally to L after initiation of crabs are possible predators. The inflated form gonad development. The co-ordinates of the may be advantageous for avoiding shell crushing turning (or "critical") point are calculated as crabs. L = 17.9 and T = 8.3 in mm. The close agreement The highly allometric growth of brachiopod· between these measurements and the size at valve inflation may also be explained by enlarge which gonad development begins strongly sup ment of the gonad during growth. As to L. ports my suggestion that shell convexity in rubellus, the gonad develops in the individuals creases to house the enlarged gonad. As to the whose shell length is larger than about 15 mm L-W relation, no significant difference in regres (the smallest adult individual ever measured is sion coefficient between the juvenile and the 14.75 mm and the largest juvenile is 21.30 mm adult was detected (Figure II-B). in shell length). The weight of the gonad in an adult individual of L. rubellus attains more than 25% of the whole soft tissue weight (Table 4). Conclusion In order to test this hypothesis, the allometric growth of gonad vs. shell size in juveniles and A common allometric trend is detected among the adults of L. rubellus was analyzed separately examined laqueid brachiopods. The trend is two- 192 Kazuyoshi ENDO A B 30 30

L.. rub.lluB L. rubellus o juvenUe 20 N =21 20 r = 0.1193 E • adult E E N =128 E ~ r =0.1167 ~ 10 10

o juvenile N = 21 r =0.989 • adult N =128 r = 0.928

3~~~~~------~--~--~~ 5 10 20 30 40 50 5 10 20 30 40 50 L(mm) L(mm)

Figure 11. "Diphasic allometry" in the relationship between L and T (A), and "monophasic allometry" in the relationship between Land W (B). Sample Rk (13, 17,80) of L. rubellus. fold; one is relative increase of valve convexity to Acknowledgements the length of the shell (L-T relation), and the other is relative decrease of valve width to the I would like to thank Prof. I. Hayami (Uni length of the shell (L- W relation). versity of Tokyo), Associate Prof. K. Tanabe Four different explanations may be possible (University of Tokyo) and Mr. R. Norris (Harvard about the L-T relation: University) for many helpful suggestions during (1) to obtain hydrodynamic stability in the the course of this study, and for critical reading free-lying stage of life, of the manuscript. I am grateful to Associate (2) to economize the secretion of shell Prof. S. Ohta [Ocean Research Institute (O.R.I.), material, University of Tokyo] for allowing me to join in (3) to strengthen valves, and the sampling cruise by R/V Yayoi and for pro (4) to host the well developed gonad. viding the samples stored in O.R.I. I wish to Of these explanations, (1) is invalid because thank the staff of the Misaki Marine Biological it does not explain the allometry in some per Station, University of Tokyo, for affording me manently attached species, and because com an opportunity to collect and observe the living pressed shells are inferred to be more stable to specimens of L. rubellus. I am much indebted to the water current. Among the remaining three Mr. E. Tsuchida (O.R.I.), Dr. T. Oji (University explanations, (4) is most convincing at least in of Tokyo), and Dr. Y. Kondo (University of the case of L. rubellus because of the apparent Kyoto) for providing the samples. Many thanks "diphasic" allometric relation between Land are due to the staff members and graduate T. No plaUSible explanation for the L-W relation students of the Paleobiological Laboratory of is still obtained. It requires a further study. the University of Tokyo for valuable discussions. 838. Relative Growth of Laqueid Brachiopods 193

References lities are roughly shown in Figure 12. All specimens utilized are stored at the University Museum of the University of Tokyo with registered numbers with pre Alexander, R. R. 1984. Comparative hydrodynamic fix UMUT. stability of brachiopod shells on current-scoured 1. Laqueus rubellus (Sowerby) Figures 1-1-6 arenaceous substrates. Lethaia, 17, 17-32. Fossil sample Jz (L) [N = 2] [UMUT CB18185] Endo, K. 1986. Mode of occurrence and significance of Locality: Yamadakubo, Ichihara City, Chiba Pre the warm-water fauna in the Sawane Formation, fecture (loc. 3). Sado Island. Jour. Geol. Soc. Japan, 92 (1),77-80. Lithology and horizon: muddy medium grained (in Japanese) sand of the Jizodo Formation of the Shimosa Hatai, K. 1940. The Cenozoic Brachiopoda from Japan. Group. Sci. Rep. Tohoku Imp. Univ., 2nd Ser., 20, 1-413, Age: Late Pleistocene. pIs. 1-12. Collector: Y. Kondo. --1965. Cenozoic Terebratellacea. In, Moore, R. C. Remarks: Same locality as loco no. 132 of Toku ed., Treatise on Invertebrate Paleontology, Part H. hashi and Endo (1984). Geo!. Soc. America and Univ. Kansas Press, 845p. Recent sample Rk (13, 17,80,82, 100, 104) [N = Hayami, I. and Matsukuma, A. 1971. Mensuration of 184] [UMUT RBI8186]. fossils and statistics - Analysis of allometry and Locality: eastern part of Sagami Bay, about 2 km variation-. Sci. Rep. Kyushu Univ., (Geol.), 10 (3), west of the Jogashima Islet (loc. 7) (35°7.9'N, 135-160. (in Japanese) 139° 35.1 'E, 80-90 m). Imbrie, J. 1956. Biometrical methods in the study of Status: living. invertebrate fossils. Bull. A mer. Mu~. Nat. H{st., Bottom substrates: coarse grained sand with 108 (2),211-252. LaBarbera, M. 1977. Brachiopod orientation to water movement 1. Theory, laboratory behavior, and field reorientations. Paleobiology, 3, 270 -28 7. --1978. Brachiopod orientation to water movement functional morphology. Lethaia, 11, 67 -79. McGhee, G. R., Jr. 1980. Shell form in the biconvex articulate Brachiopoda: a geometric analysis. Paleobiology, 6 (1),57-76. Raup, D. M. and Stanley, S. M. 1978. Principles of paleontology, 2nd ed. 481p. W. H. Freeman and Company, San Francisco. Richardson, J. R. 1975. Loop development and the classification of Terebratellacean brachiopods. Palaeontology, 18,285-314, p!. 44. --1981a. Brachiopods in mud; resolution of a dilemma. Science, 211 (4487), 1161-1163. ,; --1981b. Brachiopods and pedic1es. Paleobiology, 7 (1),87-95. 0 0 + Rudwick, M. J. S. 1959. The growth and form of bra 3d'+ + J.o 1311''- chiopod shells. Geol. Mag., 96, 1-24. 121f 130" --1970. Living and fossil brachiopods. 199 p. Hutchin son Univ. Library, London. $fe 5 Thayer, C. W. 1986. Are brachiopods better than bi e FOSSIL SAMPLE valves? Mechanisms of turbidity tolerance and I o RECENT SAMPLE their interaction with feeding in articulates. Paleo· 28"+ + biology, 12 (2), 161-174. Tokuhashi, S. and Endo, H. 1984. Geology of the Figure 12. Map showing the localities of fossil and Anesaki District. Quadrangle Series, scale 1:50,000, Recent samples studied in this paper. Fossil localities; 130 p. Geo!. Surv. Japan. (in Japanese) 1: Sawane Formation at Sawada Town; 2: Na-arai Formation at Nagasakibana; 3: Jizodo Formation at Appendix Yamadakubo; 4: Jizodo Formation at Atebi; 5: Wan Formation at Kamikatetsu. Localities of Recent samples; The following samples belonging to eight species of 6: Mouth of Otsuchi Bay; 7: Off Jyogashima Islet; 8: three genera were examined in this study. Their loca- Off Hinomisaki; 9: Off Tsukumi. 194 Kazuyoshi ENDO

pebbles and shell fragments. the lower Sawane Formation. Collector: I. Hayami et al. (R/V Rinkai). Age: Pleistocene. 2. Laqueus blanfordi (Dunker) Figures 1-7-9 Collector: K. Endo. Recent sample at (1) IN = 18] IUMUT RBI8187]. Remarks: Precise locality is loco no. 2 of Endo Locality: Mouth of Otsuchi Bay (loc. 6). (1986). Status: living. 6. Pietothyris pieta (Dillwyn) figures 1-19-21 Collector: K. Endo. Fossil sample Jz (P) IN = 10] IUMUTCBI8193]. Recent sample at (2) IN = 9] IUMUT RBI8188]. Locality: Atebi, Kisarazu City, Chiba Prefecture Locality: Mouth of Otsuchi Bay (loc. 6). (loc.4). Status: dead. Lithology and Horizon: medium grained sand of Collector: E. Tsuchida. the Jizodo Formation of the Shimosa Group. 3. Laqueus quadratus Yabe and Hatai Figures 1-10-12 Age: Late Pleistocene. Fossil sampleNa IN = 16] IUMUTCBI8189]. Collector: K. Endo. Locality: eastern coast of Nagasakibana, Tokawa, Recent sample Rk (P)[ N = 36] I UMUT RB 18194]. Choshi City, Chiba Prefecture (loc. 2). Locality: eastern part of Sagami Bay, about 2 km Lithology and Horizon: tuffaceous matrix of west of the Jogashima Islet (loc. 7) (35°7.9'N, conglomerate of the N a-arai F ormation of the 139° 35.1 'E, 80-90 m). Inubo Group. Status: living. Age: Pliocene. Bottom substrates: coarse grained sand with Collector: K. Endo. pebbles and shell fragments. Recent sample Hi IN = 13] IUMUT RBI8190]. Collector: I. Hayami et al. (R/V Rinkai). Locality: off Hinomisaki (loc. 8) (248 m), off 7. Pietothyris sp. Figures 1-22-24 Etsuzaki (165-240 m, 215-297 m), off Mugi Recent sample Ts (P) IN = 43] IUMUT RBI8195]. (248 m), off Tanabe (264 m), Kii Channel. Locality: off Tsukumi, Bungo Channel (loc. 9) Status: dead. (33°2.2'N, 132°5.4'E, 72-76 m). Collector: E. Tsuchida. Status: living. 4. Laqueus sp. 1 Figures 1-13-15 Bottom substrates: coarse grained sand with Recent sample Ts(L) IN =46] IUMUTRBI8191]. pebbles. Locality: off Tsukumi, Bungo Channel (loc. 9) Collector: I. Hayami et al. (R/V Tansei). (33°2.2'N, 132°5.4'E, 72-76 m). Remarks: st. 31 of the cruise KT-84-12. Status: living and dead. 8. Kikaithyris hanzawai (Yabe) Figures 1-25-27 Bottom substrates: coarse grained sand with Fossil sample Wa IN = 33] IUMUT CBI8196]. pebbles. Locality: road-cut about 500 m north of Kami Collector: I. Hayami et al. (R/V Tansei). katetsu, Kikai Island, Kagoshima Prefecture Remarks: st. 31 of the cruise KT-84-12. (loc.5). 5. Laqueus sp. 2 Figures 1-16-18 Lithology and Horizon: coral sand of the Wan Fossil sample SW IN = 44] IUMUT CBI8192]. Formation of the Ryukyu Group. Locality: Kaitate, Sawada Town, Sado Island, Age: Late Pleistocene. Niigata Prefecture (loc. 1). Collector: I. Hayami. Lithology and Horizon: coarse grained sand of

B*£5'z~~M~~~.~~.tm~ •• :B*£M~~5'z~~M~~~.tt,M~ ~~~':':}.;~'-Cm~ ••~.:. 2 '?~m[tl]~jf--t, ~.~.:.~-t;g~~.s, < G~~m~~!f!l.t]Q t~.~.:.~ -t;g ~.j~m~~~t}'-r: ~;g, .: h G ~~ •• ~L\j{IZSI~%l;g t::.bb~.:.:m~ Laqueus rubellus (Sowerby) ~:±:~.:.ffl~'-C, ~., ~.:}';.l: lf~~ ••I.:.~:il-t;g~, < ,?;Q'~~:I:~m~ •• ~Wi\1 .r{.t::., ~~.s,< G~~m~~!f!l*~l!I!.rEt L-C, (1)~.11{~*-!fA=~tt~, (2)~!Ml~~!f!l*, N.,'U'( (3)~M~J/X.Kfi~~- ~~lil{Jf:~ 3 '?~imJJJltMf;:t Gh;g, L. rubellus I':'~ L -CIt, .~~.:.:}.;~ '-C ~~.s, < G~;Q~~.I.:.~L -c1il •• ~jf--t~I':'~L, ~M~~ ~ t::.t.J:~'*b~~':':},;~'-Clt, ~~.s, < G~c~.~~f*lt~ ••~jf--t.: i::.7J'G, ':hG~? '!;,(3)~imJJJlil~)ji~~j;JJ-r·~;g, J!i!ii-{i 195

PROCEEDINGS OF THE PALAEONTOLOGICAL SOCIETY OF JAPAN

El*0) J:(,110 W*-IJ" ~ ~ =- 7 ~Il}f EI t;::fiii;lf9i'<.lz:W~AAi:r#Hlli~tLt.: (~1JU~122~)o 1:=.@/'f··.·· ...... fIJ~ID£- Further notes on Parasolenoceras (hetero OOA.~;~ morph ammonoid) from northern Hokkaido =F J&j/ ~.J: IJ j£: f±l L.td~Hi1ft15 C -t:- 0) Xllfi ...... T. Matsumoto and T. Miyauchi ...... * i!f-. :ljHtJII'!.ff.~ 8 ill! *c 7 ~ ~ -r -1 ~ Neopuzosia c Kitchinites fiii;lf9i' Aztlanolagus *7 Y 7 0):; "- 7 ~c#ii1:.::::t:lc~~O)1:.~:!1f!l!Il. .... ~ ('7-1J"=¥f1D O)feT~J!CP.!ffeTili:t;:::toIt7.>~t* ...... ~* f'I:l '7-1J"=¥MO):I.&1lX ...... lJBl$~· A.J. Winkler ~~JfiHI!l~m1t1li0)~7'R.~~j£:::::t:lc~ ...... *~P~~70)*feTili:7·~~~~AmD.~ ...... B3 f\;lEz • t£~*~ t;:: ,?~, -C ...... l'ffip I=l r.!IRJ *fBBW~cO) :11-7 ~ ? AMt;::-?~'-C -t:-O) 1 .. 15 JlI9i'<-e,iji m O)-e,iji15 ER'I!:t1&~ j/ (1!ijf;~- ...... ·1liili,*1:. ~feTili: Nassellaria (:I.&IlX.!R) 0) cephalisO)i'lB!it;:: !l!i~lll!:I=l~:l* (2(X5f;) O):tc:lE!1:t;::'?~'-C-~* ,?~, -C ...... t'rNIJRJ ~ri:0)~~~(~!1:2~~) O)mWi~:l**~ *feTili:JfJf!~i1ffi.J.ftiH·O)~f'F c * EI **:ifi!f{J!U.~t 1;::00 -t 7.> ~1i1f~~-· ...... ~ B3 ftl't= If!1Ti!fi t;:: ?a "? t.: i1l1lii$rtrD~ ...... :JLIlJ~1jij 'HHli);:::to1t 7.>~~ Mandarina O)~1mrtr~ .. 7~~~0)*.A~7~-~ -t:-0)5-1:.A~~c ...... 'T~ 1ft ~]t~0)~~ ...... ~~~~ 1:.mftEil' t;,J!t.: '7 =- O)i11:.1m-r~t~~~mJ\j 1l'~.!R Cythere ~O)1W{;$:~1:.b~Niit .... ~.@g ~ 0){J1j- ••.••••••••.••.••••.•••.••••• • ~Riil- ~1!imJO)mJ~~fIl\.*O)f!~ ...... )jgiJ; ,. ~M'7i~~MO)~O)BWc-t:-o)~*KM-t7.>~ iIlt.$.9i'

New members approved by the Council Meeting held on June 19, 1987. Ordimary Members: Zhou, Baochun; Matsubara, Akiko; Ikejiri, Hiroyuki; Okura, Masatoshi; Hachiya, Kiichiro; Ohe, Fumio; Okamoto, Masanori; Kaneko, Naomoto; Takai Yuji; Jochi, Kotohiro; Ota, Yasuhiro; Kiyokawa, Shoichi; Nagai, Hiromi; Kobayashi, Mariko; Ogata, Masashi; Kohno, Naoki; Koizumi, Akihiro; Isaji, Shinji; Satoh, Atsushi; Uematsu, Tomosaburo. Deceased Member: Kuroda, Tokubei (Honorary Member). Withdrawing Members: Takamura, Kazuko; Sasakawa, Seiichi; Ookura, Mitsuko; Nakagawa, Hideki; Yasuhara, Naoki (Ordinary Mmebers), Nichu Sekiyu Kaihatsu (patoron).

IPA(7) World Direcfory of Paleontologists ,;:~Jiij~~~ff;~1t';l:.

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World Directory of Paleontologists

QUESTIONNAIRE (please print or type responses using roman alphabet)

Family name or surname (we will be unable to print diacritical marks):

Individual name or !irst name in full and middle initial:

Address (institution, if any, street number or post oflice box, city, state/province, country and postal code):

Business phone number, including city or state area code:

Principal areas of study (either systematics, i.e. Brachiopoda; or topical, i.e. evolution). Please answer (A) or (B); or (A) and (B):

(A) Maximum of 2 specializations on fossil groups, with stratigraphic range and geographical area of interest (if possible, list higher taxonomic categories, i.e. phylum or division, class, or order): (1)1 ______Range: ______Area: ______

(2) ______Range: ______Area: ______

(B) Topical approaches (cladistics, functional morphology, biostratigraphy, ecology, evolution, etc.). Limit is 10 words or less:

Example of entry:

GRANT, RICHARD E., NATURAL HISTORY BLDG. E-207, SMITHSONIAN INSTITUTION, WASHINGTON, D.C. 20560, USA. (202) 357-2211/2405. BRACHIOPODA: PERM., W. U.S., TETHYS. BIOSTR., ECOL., FUNCT. MORPH.

Please complete and return this questionnaire by Dec. 31,1988 to: Rex Doescher, NBB E-207, Smithsonian Institution, Wash., D.C. 20560, USA. This questionnaire may be copied for secondary circulation. 00 H€ :ttl! 00 it B ~iJii$~hB

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Errata for No. 146 p.42 and back cover, 829. MATSUMOTO and YOKOI; title read (Studies of Cretaceous Ammonite from Hokkaido-LXI) for -LX.

B * iJ ~ ~ ~ f. 1 9 8 7 if. 10 ]cJ 24 U ~n ~ Jl\ IR ~r.1: 2-4-16 1 9 8 7 if. 10 fJ 30 [I ~ 1l*~~.:m-e/?-f1;) ISSN 0031-0204 (~~J:ll¥: ** 847 8 O~) ('itt ;i! 0 3 - 8 1 7 - 5 8 0 1 ) m~~!A.~· iWifi'iV;iE .~~* ffflla'fnJ ~n ,\jlIJ ~ J\( Jl\ fU1L!!(, IR ~~~ .:Ut 2 <7) 13 2.500r1J ~j!f.j~]:;t}f.IJIilIJl*J:\~ll ii'," fH ~ (~ .ffi 0 3 - 9 9 1 - 3 7 5 4 ) Transactions and Proceedings of the Palaeontological Society of Japan

New Series No. 147 October 30, 1987

CONTENTS

TRANSACTIONS 832. TASHIRO, Masayuki: CretaceousEomiodon and Costocyrena (Bivalvia) from southwest Japan ...... 91 833. KOBAYASHI, Teiichi and HAMADA, Takashi: The third addition to the Silurian trilobite fauna ofYokokura-yama, Shikoku, Japan ...... 109 834. NIKO, Shuji: Early Carboniferous Eostaffella (primitive Fusulinacea) from the Ichinotani Formation, Fukuji district, central Japan ...... 117 835. KOBAYASHI, Teiichi and HAMADA, Takashi: On the Silurian trilobite faunule of Hitoegane near Fukuji in the Hida Plateau, Japan ...... 131 836. MATSUMOTO, Tatsuro, ASAI, Akito and HIRANO, Hiromichi: Some inoceramids (Bivalvia) from the Cenomanian (Cretaceous) of Japan-II. Three species from Hokkai- do, well known abroad but hitherto undescribed in Japan ...... 146 837. TANABE, Kazushige and SHIGETA, Yasunari: Ontogenetic shell variation and streamlining of some Cretaceous ammonites ...... 165 838. ENDO, Kazuyoshi: Life habit and relative growth of some laqueid brachiopods from Japan ...... 180 PROCEEDINGS ...... 195