a -lt"~±~T~ ~~·!c.f Transactions and Proceedings of the Palaeontological Society of Japan New Series No. :~2 Palaeontological Society of japan Novl:mber 10, 1958 CONTENTS TRANSACTIONS Page 348. On the !VIiocene Pectinidae from the Environs of Sendai; Part 12. On Pecten kagamianus Y oKoY Al\IA ..................... ................... 1\oichiro iVlASUDA 271 349. Molluscan Fauna from the Tertiary Formation of Chirai. 1\amisaroma. Kitamino·kuni, 1-Iokkaido ...... .. Wataru ll."-SIMOTO and Saburo KANNo 285 350. Late Triassic Palaeoplwms in Japan ... .. ...... .... .. .... .. .... ... Akira ToKUYAMA 291 351. An Interesting Crustacean Remain, Ctenocheles sujalmi n. sp. from the Pakogene of Kyushu. Japan ........................................... Rikizo IMAIZUMI 299 PROCEEDINGS .............................................................................................. 305 Systematic Index 307 Index of Fossils .................... 309 President : Hisakatsu Y AnE Councillors: Kiyoshi AsANo. Riuji ENoo (Business and Accountant). Seido ENoo, 1-Iaruyoshi FuJII'.IOTo (Publication). Shoshiro HANzAwA. Kotara HATAI, Ichiro HAYASAKA (General Affairs), Kazuo HuzioKA, Teiichi KonAYAsHI (Editor), Jiro l\iAKIYAMA, Tatsuro MATSU~IoTo, Masao l\iiNATo, Tokio SHIKA:o.tA, Fuyuji TAKAI (General Affairs). Ryuzo ToRrYAMA Secretary: Tetsuro I-IANAI Assistant Secretary: Takeo IcmKAwA All Communications relating to this Journal should be addressed to the PALAEONTOLOGICAL SOCIETY OF JAPAN Geological Institute, Faculty of Science, University of Tokyo, Japan Trans. Pror. Palaeont. Soc. japan, N. S .. No. 32. pp. 271- 21'\'l. pis. 40~1 I, J'\ov. 10, 1958 :348. ON THE ;\fiOCENI:: PECTINlDAE FROl\1 'rHE ENVIRONS OF SENDAI : PART 12. ON PECTEN KAGAMIANUS YOKOYAMA* KOICHIRO rviASUDA Departnwnt of Geology, Faculty of Education. 'Tohoku University ltittl'llf.t.i/i:rl~f!i*fedf,' Pcctinidac: -'CO) 1~. J>ec/elr kagamimms YoKOYAMA :c ..:n,-c: f.lOI!: Pecten kagamianus YoKOYAMA t t. ft 'L$t.:: r. *?-r.!t!!:l.l· t:, CD~ t~O)~)j>::~ '?~ 'l'M'itH..t.:f.li\1!:. Patinopecten kagamianus lmgamiamrs (YoKOYA:IlA), Pat. kagamiamrs monirmensis MASUDA. n. subsp., Pat. kagamiamrs nimaensis !viASlJDA. n. subsp., Pat. kagamimms permirus (YOKOYAMA) 0trniffifili:-:.J}tt J? ttJ., c. c v:bl'J·? t.:., Ut ~:, v)~ -'< r:::-:>t-L'Jcl~~ rrP. t'rHWHO)OOf*'· it!!'t'l".f.f!'~'"' Among the fossil Pectinidae knO\Yn Introduction and Acknowledgements from the l'vliocene formations of Japan. Pee/en lwgmnianus is of particular in­ PPc!en lwf.[amianus was first described terest because of its confusing characters. by YoiwYAMA from the Kimachi forma­ limited geological range, more or less tion at 1\agami. Kimachi·mura. Yatsuka­ similar lithology of the formations in gun, Shimanc Prefecture in 1923. Sub­ which it occurs. and rather wide geo­ sequently it was reported by him as graphical distribution. Pecten pennirus and Pecten PPrmims Numerous specimens from the Nanao var. paucicostata from ncar .1\anao, Noto formation in Ishikawa Prefecture. and Peninsula, Ishikawa Prefecture (1926). from the J\1oni\\'a and Oido formations Later. the same author (1939) included in Miyagi Prefecture. those preserved Pecten permirus and P. permirus var. in the Institute of Gcologv and Palcon· paucicostata in the synonym of Pectrn tology, Faculty of Science. Tohoku Uni· (Patiuopn·ten ?) lwgamianus YoKOY c\MA, versity, and in the Saito [-lo-on Kai ?vlu· with the statement that it sho\vs con­ scum. both in Sendai City, and the mate· siderable variation in the number and rials in the Institute of Geology, Faculty size of the radial ribs. l'viATsuMoTo (1930) of Science. University of Tokyo in Tokyo, described Pecten p!icicostu!atus as new were studied by the writer. The results to science from the l\ioniwa formation of examination lead the writer to con­ in the environs of Senclai City, but this sider that !wgamianus may be classified species was included into the synonym into four subspecies. of Pecten !~agmnianus YoKoYAMA by No­ In this article the \\Titer describes the MURA (l9AO). These different names sho\Y morphological characteristics of the that the present species exhibit variable kagamianus group. and discusses their characters. relationship with related forms. The * ReceiYed Feb. 5, 1958: read at 66th meet­ geological significance, so far as can be ing of the Society at Akita. June, 15, 1957. judged from the field data, is also given. 271 272 Koichiro MAsuoA Acknowledgements are due to Dr. Ko­ a fe\\· longitudinal striae which are pre­ tora liATAr of the Department of Geology, sent also on the latter. Shell margin Faculty of Education, Tohoku University. coarsely crenate. The ears seem to be for his supervision. Thanks are due to subequal. though the anteriqr is a little Prof. Sotoji IMAMURA of !he Geological broken. Length and height 105 mm. and ivlineralogical Institute. Faculty of Thickness 25 mm.'' Science, and l\lr. Kazuo 0~-:AllloTo of the Remarks :-This species is characteriz­ Department of Geology, Faculty of Edu­ ed by the large. orbicular. compressed. cation. both of the Hiroshima University. subequivalve. equilateral shell. flatly for their kind offer of !he specimens rounded radial ribs which are broader which they collected from the 1\'Iiocene than their interspaces and divided into deposits in Shimane Prefecture, and also a varying number of longitudinal riblets to l\liss Yoko SuzuKI and Mr. K6ki Nr­ on their backs in the right val \'e. and HEI, students of the Faculty of Educa­ by the left valve having the rounded tion, Tohoku University, for their assis­ radial ribs narrower than the interspaces tance in the collection of some specimens. and diYicled into a few riblets by shal­ low longitudinal furrows. Description The present species has been reported as Pecten. Patinopecten, and Vola and Family Pectinidae HATAI and NisiYAMA (1952) referred it to Lyropecten. However. the genus Lyra­ Subfamily Pectininae pecten is characterized by having the Genus Patinopec/en DALL. 1898 valyes with a hump or wave on the umbo and with distinct intercalary Patinopecten lwgamimms threads in the interspaces, and by the (YoKOY A~IA). 1923 hinge furnished with three distinct. obli­ que. divergent cardinal crura. 1923. Peel ell kagamiaiii/S YOKOYAMA, japan. Although the generic position of this jour. Geol. Geogr .. Vol. 2, l'·io. 1. p. H. species is doubtful. the writer refers it pl. 1. figs. la-b. to the genus Patinopecten with query. YoKOYAMA's original description is as The specimens of the present species follows: "Shell large. moderately thick. from the yarious mentioned localities much compressed (the right ,·alve a lit­ show variable characters, and based upon tle more than the left), orbicular, sub­ several features they can be classified equivalve and equilateral. Both valves into four subspecies. They are closely radiately ribbed. The ribs on the right related with one another. but may be valve sixteen in number, broad and flatly distinguished in their number and nature rounded, straight. broader than the in­ of radial ribs. the apical angle and the terspaces and with a varying number of depth of valves (Table 1, and figs. 1. 2, longitudinal striae on them; the inter­ 3:'. The distinguished ones are Patinopec­ spaces shallow, usually a little narrower ten kagamirmus kagamianus (YoKOYAMA). than the ribs and also longitudinally Pat. lwgamianus moniwaensis !'vlAsuoA. n. striated. The ribs on the left valve subsp .. Pat. lwgamianus nimaensis .\IAsu­ about equal in number to those of the DA, n. subsp.. and Pat. lwgamianus per­ right, straight, rounded. much narrower mirus (YoKoYAMA). respectively. These than the interspaces and furnished with are considered to be geographical or On the l'vliocenc Pectinidae from the Environs of Scndai 273 allopatric forms (lVlAYR, 1942). ly lVIiocene. 1~vpe locality, Geological formation and Depository :-1-Iolotype. Geological Insti­ Age:- Kagami. Kimachi-mura, Yatsuka­ tute. Faculty of Science. University of gun. Shimane Prefecture. (Lat. 35'25 N .. Tokyo. Long. 13~·58'1-:.) Kimachi formation. Ear- ,...., E E ~ -= ~ -l 115 8 1u5· 1f1R -v-rus- -uo- 12 :!3 I~ 113 I ~~ 11 100' 16 R F 107 llO ·10 II 105' 2-1 ~ 113 10 100' 17 'I R F 59 60 22 4 100' 26 R 78 I ~~ 7 too· 16 R F 57 56 22 4 100' 23 R 26 11 2.5 I OW lfi R F 38. 5 36 15 3 IOU -19 11 100' 16 I. F 36 3·1 : ~~: ~~ ! l~ I 9!i ·15 10 100" HI L F 32 32 2. 5 lllO • 26 I~ 88 10 I ou' 16 I. I F 93 92 12 !Ott• 21 L S!i 38 10 100· 17 L I F 87 85 ·Hi 21 ·I 100' 16 F 71 70 ' 30 I I }: II 1 Ll 1 5 : ~. 1 ~~: ~r 8!i 8 I 0 0" 1 7 R F ·13 41 ' 17 5 I 05' 24. I. 70 I :lO 5 I 0 0' 18 R F 42 38 15.5 4. 5 100' 2·1 I. f>ll 7 IUO' 17 f 16.5 15.6 ~/,,, r: 2 lliU' 21 L ---- ----5-f' Ll -------'-·oov-1'1-f< G: 127 I:l6 50 I 05' 28 R II 0 39 I too· 12 R G 121 1:.!8 50 J:i 110· 29 7·1 8.5 IIJO" 10 t<i G 20.5 1!1.5 !l I UU" 25 R'~I -18 Jli5' 12 R' ~ G 106 98 I ·H 100' 21 L 2-1. 5 7. 5 no· 10 R S c 66 65 28 1o5· 1 25 '­ ·IIi 6 12 I~ ~ G •16 11 I!J Juo· 25 1. ;{!i I (i 37 100' 9 R ;:; II 53 50 100' I 21 'I~ 19 17 10. 5 100' 10 R"':-H 104 103 12 110' :!-1 JJ 1 113 1111 ·18 18 : 105'' llL'"<IJ 100 101 }3 105' I 25 1. 105 101 IS 11 L I 63 60 5 1uo· 27 I~ 1 38 35 17 100, _,?~ - I 9 L C 73 II 5 I O!i' ''5 Rl 35 34 18 4.