Trans. Proc. Palaeont. Soc. Japan. N.S. No. 18, pp.31-36. Pl. 6, 1 text-fig, June 20, 1955 264. TERTIARY MOLLUSCA FROM TAISHU MINE, TSUSHIMA, NAGASAKI PREFECTURE, JAPAN* SABURO KANNO Tokyo University of Education, Tokyo 対 馬,対 州 鉱山 産 介化 石 につ い て:対 馬 の鉱 州鉱 山 か ら採 集 され た 介化 石 群 を検 討 した結 果14種 を 固定 した。 その 結 果 これ ら介 化石 群 を含 む 地 層 は今 迄 考 え られ てい た よ りも若 く漸新 世後 期 または 中 新 世初 期 の も ので あ る こ と を指 嫡 した 。 菅 野 三 郎 ascribed because of their bad preserva- Introduetion tion. I. TATEIWA collected a small flora Through the kindness of Mr. I. S AG A . from a dark grey shale exposed on a geologist of the Toho-Aen Company. the roadside cutting near the vilktge of writer had a chance to study the mol- Kotsuki in Shimo-jima and from a similar fossils collected from theluscan Taishu shale rear the enhance to the village of Mine in Sasu-mura. Tsushima Island, Salta in Kami-shima. From the flora Nagasaki I refecture. Japan. which comprises 16 forms of plant leaves, With regard to the geology of the he determined its geological age to be island. there are three reports, namely, Cretaceous-I'aleogene. by T. NASA (1891). D. SATO (1908) and Such being the state of our previous I. TATEIWA (1934). T. NASA pointed out knowledge on the geologic age of these that the island consists essentially of beds, the present fauna is considered to disturbed alternating beds of shale and have important bearing on the problem. sandstone intruded in places by granite. The writer wishes to express his gra- quartz-porphyry. porphyrite etc. These titude to Mr. I. SAGA, geologist of the rocks. he stated, show resemblance to oho-Aen Company, for kindly offeringT the Juraisic series of Central Japan. his collection for examination and for However, he found no fossils. D. SATO oral information concerning their geolo- divided the strata into Lower and Upper . gical occurrence, and to Drs. Haruyoshi The former occupies the northwestern FOJIMOTO and Kotora both of part of Kami-shima and the latter the our Institute, for their constant guidance remaining part of the island. Their during the course of the present work. boundary extends northwesterly from Fossil localities and occurrence Waniura to Inugaura. From lithologic similarity, he compared the beds with The Taishu group (TATEIWA, 1934), the Mesozoic rocks of southwestern Japan, generally speaking, is an alternation of and with those of south Korea Although dark grey sandstone and black or dark he recorded the occurrence of the mollus- grey slaty shale, each having a thickness of about 10cm. And there often is a can and plant remains, no definite age was ripple mark between the sandstone and *Read . Oct. 9, 1954; received Nov. 7. 1954 the shale. 31 3 2 Saburo KANNO Text-fig. 1. Maps showing the locality. So far to date. fossils have been hardly MARTIN reported from Tsushima excepting plant 5. Patinopecten kimmrai (YOKOYAMA) and a few fragmental molluscan fossils. 6. Cyrena aff. mrirnbilis NAGAO•cPl . 6, Fig. 9 However. molluscan fossils were dis- A single specimen. covered in 1953 by 1. SAGA from in the 7. Lucinoma sp. A single fragmentary Shintomi-pit and Himi- pit of the Taishu specimen•c•c•cPl. 6, Fig. 10. B. Vencricardia cf. yoshigai Mine (Text-fig. 1). The fossils were derived from a one meter thick shale NAGAO•c•c•cPl. 6. Fig. 11 9. Mcrdrix aff. pseudomesetrix intercalated in the alternation of sand- NAGAO•c•c•cPl. 6, Fig. 12. stone and shale. The shale, although A single specimen. massive, appears as a breccia in con- 10. Dosinia cf. chikuzenensis NAGAO11 taining a number of angular pumice, . Tellbia sp. quartz-porphyry and porphyrite. 12. Phaxus all. izonoensis (YOKOYANIA) The 14 species which are each re- 13. Euspira cf. ashiyaensis presented by only one or several indivi- (NAGAO)•c•c•cPl. 6, Fig. 17. duals were obtained from the Shintomi- III preserved specimen. 19. Neveria insignis (NAGAO) A single pit. The shells are rather well preserved specimen•c•c•cPl. 6, Figs but are impregnated with pyrite in part. 18a-b The distinguished forms are: 1. Aclia (s. s.) sp. A single fragment. Geologic age of the Taishu fauna 2. Nucule (Lamellinucula) cf. hizencnsis NAGAO•c•c•cPl. 6, Fig. 1. T. NASA (1891) considered the beds A single fractured specimen. in question to be Jurassic in age from 3. Anadara sp. A single fragmentary their lithologic resemblance to the Juras- specimen•c•c•cPl. 6. Fig. 2. sic strata of Central Japan. D. SATO 4. Chlanays (Coralichlamys?) cf rutteni (1908) claimed them to of Mesozoic Tertiary Mollosca from Taishu Mine, Tsushima, Nagasaki Prefecture, Japan 3 3 because of their lithologic resemblance Chlamvs (Coralicklamys?) cf. ruttleni with the Mesozoic rocks of Nagato, MARTIN, 1914 southwestern Japan. and with those of south Korea. However, I. TATEIWA Plate 6. Fig. 3 (1934) pointed out that the beds. front 1952. Chlamys (Coralichlamys?)mtteni MIZUNO, their plant fossils and stratigraphic con- Trans. Proc. Polaroid. Soc.. Japan (N.S). sideration, are of Cretaceo. Paleogene age. no, G, pp.188-189. p1. 17, fig. 6. So far as the flora is concerned, a Lower Tertiary age seems possible, but he was A single right valve. It is broken at inclined to regard the beds are rather its umbonal and postero-dorsal parts, old owing to the stratigraphic relation and measures 6.0mm in length and 6.4mm of them to the rocks that intruded beds. in height. This specimen has a small These intrusive rocks are probably con- shell and more than twenty narrow temporaneous with the eruptive rocks of radial ribs which are separated by the Bukkokuji group of south Korea, broader interspaces. whose eroded surface is covered by the Choki series which contains a Paleogene flora of the so-called Arctic Miocene Genus Patiaopcctcn DAD., 1898 type. The present molluscan fauna, although Patinipecten kimurai (YOKOYAMA), 1925 inadequate for discussing the chronologi- Plate 6, Figs. 4-8 cal age, is important in that there is no evidence for a Cretaceous age. The 1925 Peden kinturai YOKOYAMA, Jour. Coll molluscan fauna is similar to that of Imp. Univ. Tokyo, vol.45, art.Sci., 5, the Paleogene Ashiya group in northern p.27, pl. 4 figs. 1-6, p1.2. fig.1. Kyushu. Japan. However, Patinopecten Shell large, orbicular. more or less kimurai (YOKOYAMA) and the genus compressed. subequilateral. the entero- Dosinia are dominant elements in the dorsal margin being slightly longer than early half of the Miocene in Japan. the posterodorsal. Surface with radial The plant fossils reported by TATEIWA ts. Night valve with eight radiatingri seems to be of Tertiary age. Therefore. ribs with no longitudinal riblets or striae the writer concludes that the geological on their backs, separated by shallow age is late Paleogene or early Miocene. valleys of about equal breadth which However, it must he kept in mind that the age is restricted to the fossiliferous are smooth at bottom and show no demarcation against the ribs. Ears sub- beds and not to be the whole. There- equal, the anterior one smaller, triangu- fore, it may be added that detailed strati- lar in outline with its anterior border graphic work is necessary to clear the somewhat convex ; byssal notch hardly problem existing between the fossilifer- developed posterior ear also triangular ous beds to the geology of the island. but gently curved from the hingedine to the posterior border. Isolated left valves which probably belong to the Systematic Description same speci are less convex, provided Family Pectinidae with fine network, granular ornamenta- tion and radial ribs; ribs about eight in Genus Chlamys RODING, 1798 number, roof-like, sharp, with valleys 3 4 Saburo KANND equally formed, that is to say broadly is more or less compressed, it resembles -shaped: ears subequal. triangular.V pro- the paratype (fig. 14) of the named vided with a few radiating riblets. species figured by NAGAO from northern Hinge-line nearly straight but oblique. Kyushu, Japan. Dimensions: 39.8imm in The largest specimen (fig. 4) is 81mm length, 38.1mm in height. in height, about 80mm in length and 36mm in length of hinge-line while Family Tellinidae another (fig. 5) measures 20mm in height, 20.5mm in length and 9mm in Genus Tollina LINNE, 1758 length of hinge-line. Remarks:-The specimens resemble Tellina sp. indet. Palinopecten kintrai (YOKOYAMA)(1925) Plate 6. Fig. 15. from the Jo-Ban Coal-field. but diverge therefrom by having no radial striae Shell of moderate size, compressed, on the ribs of the right valve. and more transversely elongate-ovate in outline. elevated and rigkl ribs. P. murayamai Anlcro-dorsal margin fairly arched. pos- (YOKOYAMA) (1926). is also similar but tero-dorsal marigin straight with an in- is distinguishable by having equilatcral distinct excavation behind the umbo), valves. and in having the right and left and forming an angle of about 145•‹ valves nearly equal. P. kimurai ugocnsis with the antero-dorsal. Anterior end HATAI and NISIYAMA (1940) differs by evenly rounded, the posterior one ros- having subequal valves. no strong radial trate and subtruncate; ventral margin ribs ankl smaller shells. P. kimurai broadly arcuate. Umbo small, pointed, tiganouraensis NAKAMURA(1910) is dis- inconspicuous. Surface with crowded, tinguishable by having a less number narrow and incremental concentric lines. of ribs which are gently elevated and Test thin. Hinge plate and tecth un- broadly rounded. P. kykskucnsis (NAGAO) known.