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Trans. Proc. Palaeont. Soc. Japan. N. S., No. 52. pp. 145-153. pls. 22, 23. Dec. 10, 1963 461. THE SO-CALLED PATINOPECT EN OF JAPAN* KOICIIIRO MASUDA Department of Geology, Faculty of Education Tohoku University 本 邦 産 い わ ゆ るPatinopectenに つ い て:本 邦 産 のPatinopectenと 北 米 産 のPatinopecten を 比 較 検 討 し た 結 果.従 来 日本 か ら報 告 さ れ た い わ ゆ るPatinopectenは,そ の 殆 ど が 北 米 の Patinopectenと は 別 系 統 の も の で あ る こ と が 明 ら か に な っ た 。 唯Pecten tokunagai YOKO- YAMAは Patinopectenの グ ル ー プ に 属 す る も の で あ る と 考 え ら れ.こ れ に 薄 し てYabepecten な る 新 属 名 を 与 え た 。 更 に い わ ゆ るPatinopectenに 対 し て は Fortipectininaeな る薪 亜 科 を 設 定 し 従 来Patinopecten(S.S.)と 考 え ら れ て い た も の に 対 し てMizuhopectenな る 新 属 名 を 与 え.本 邦 産Patinopectenの 再 分 類 を 行 っ た 。 増 田 孝 一 郎 given from various localities distributed Introduction throughout Japan and Korea. Among the Tertiary or Pleistocene Pectinidae Patinapecten was established by DALL of Japan Patinopecten has been consider- in 1898 as a section of the genus Peden ed to be one of the important and in- based upon a Northern Californian scal- teresting scallops, particularly from the lop. Peden caurinus GOULD. Thence view point of geographical distribution, Palinopecten has frequently been record- restricted geological range and intimate ed from the Recent seas of the Northern relationship with the Californian scallops. Pacific, Tertiary and Pleistocene deposits Lately ANIYAAIA(1962) has discussed on of Japan and of the West Coast of North the phylogenetical relationship between America. Patinopecten has not been the North American Patinopecten and recorded from other regions. the Japanese Patinopecten, and concluded In Japan Patinopecten was first used that some American species of Patino- by KURODA (1932) as a subgenus of Pecten based upon a Recent scallop. pecten migrated from Japan during the Miocene to Pliocene age. But from the Pecten yessoensis JAY and also for about study of the Tertiary Pectinidae of ten fossil species such as Pecten tokyo- Japan the present writer (1962a) doubted ensis TOKUNAGA.Pecten kagainianus whether the genus Patinopecten in usage YOKOYAMA. Pecten takahashii YOKO- in Japan can be identified exactly with AMA. etc. Thenceforth, there Y have the Patintopecten of Western North Ame- been published many works in which rica. though the genus Patinopecten was descriptions, illustrations or only lists employed for the Japanese Tertiary of Patinopecten, Recent or fossil, are scallops at that time. x Received Feb . 1, 1963: read at the Many specimens of fossil and Recent annual meeting of the Society at Tokyo. Ian. species of Patinopecten from the West 19, 1963. Coast of North America and numerous 145 146 Koichiro M ASUDA specimens of all known species of the versity. for his contiguous encourage- so-called Patinopecten in Japan were ment and supervision during the course studied with regard to the above men- of the present work and to Dr. Edwin tioned problem. The specimens studied C. ALLISON of the Department of Geo- included those now preserved in the col- logy, San Diego State College, for his lections of the Department of Geology. kind offer of the Californian specimens. Faculty of Education, of the Institute of Acknowledgements are due to Dr. Tada- Geology and Paleontology, Faculty of shige HAME of the National Science Science. both of the Tohoku University. Museum, Tokyo, for his encouragement and of the Saito Ho-on Kai Museum, all and to Dr. Shozo HAYASAKA of the In- in Sendai City, and the collections of stitute of Geology and Paleontology, Fa- the National Science Museum and of the culty of Science, Tohoku University, for Geological and Mineralogical Institute, his discussion on paleontology problems. Faculty of Science, Tokyo University of Thanks are due to the Saito Ho-on Education, all in Tokyo. Kai Museum, Institute of Geology and The results of examination of those Paleontology, Faculty of Science, Tohoku specimens show that almost all of the University, both of Sendai City and to species of the so-called Patinopecten in the National Science Museum and the Japan differ from the true Patinopecten Geological and Mineralogical Institute, of North America and that the so-called Faculty of Science, Tokyo University Patinopecten group in Japan may be of Education, both in Tokyo, for per- classified into five genera and be includ- mission to study their collections. ed into a subfamily different from the Pectininae which includes such genera Notes on the genus Patinopecten as Pecten and Patinopecten. However, only one species, the so-called Patino- In 1898 DALL (p. 695) established Pati- pecten tokunagai (YONOYAMA),a Pliocene nopecten as a section of the genus Pec- species of Northern Japan, can be con- ten and gave the following diagnosis : " Valves with small ribs sidered to represent an undescribed , fiat on the genus of the Patinopecten group. right valve and sometimes dichotomous; In the present article the writer des- smaller and more rounded on the left cribes the morphological characters of valve ; concentric sculpture inconspicu- the true Patinopecten of North America ous ; radial striae absent or obsolate ; and the so-called Patinopecten of Japan, ears subequal ; valves nearly equilater- proposes a new classification of the al '. Palinopecten group in usage in Japan, At that time he designated Pecten and discusses on the paleontological caurinus GOULD, a Recent scallop of significance of the so-called Patinopecten Northern California, as the type species of Japan. and included into this section such fossil species as Pecten meekii CONRAD and Acknowledgements Pecten expansus DALL. Subsequently ARNOLD (1906) raised The writer wishes to express his deep Patinopecten to subgeneric ranking and gratitude to Professor Kotora HATA] of included the following scallops, Pecten the Institute of Geology and Paleonto- caurinus GOULD, Peden coosensis SHU- logy, Faculty of Science. Tohoku Uni- RD. Pecten dilleri DALL, Pecten. healeyiMA 461. So-called Patinopecten 147 ARNOLD, Pecten oweni ARNOLD, Pecten at each extremity of hinge more con- purisimaensis ARNOLD, Pecten propatulus spicuous than that of right valve. CONRAD and Pecten turneri ARNOLD. These characteristic features can be Subsequently. GRANT and GALE (1931) observed in Patinopecten healeyi (ARNOLD) gave the following diagnosis to the sub- at hand from the Pliocene formations in genus Patinopecten. California. But the auricular crurae of "Shell large, thin, sometimes of a the inner margin of the auricles in somewhat pearly texture. having a cir- Patinopecten caurinus (GOULD) and Pati- cular outline and very low convexity, nopecten healeyi (ARNOLD) are not so valves usually equal, although at times conspicuous compared with those of the one or the other may become nearly flat : Amusiinae. radial sculpture consisting of distinct Recently MACNEIL (1961) distinguished ribs without minor striation. sometimes the subgenus Lituyapecten from the with microscopic cross-hatching, ribs of genus Patinopecten based upon the fossil the right valve comparatively broad and specimens from Alaska and California. squarish. sometimes with a medial sul- At that time he designated Patinopecten cus, those of the left valve narrow. (Lituyapecten) lituyaensis MACNEIL as the often sharp. with intercalaries if the ribs type species and included several known of the right valve are sulcated ; hinge and new species into Lituyapecten. Ac- line usually short, ears of almost equal cording to the original description and length, byssal notch deep in the older igures the subgenus Lituyapecten seemsf species. more shallow in Recent species ". to have the same characteristic features At that time they included several of the hinge area as of Patinopecten. fossil or Recent species distributed from Under the genus Patinoperten (or sub- Alaska to Oregon into the subgenus genus Patinopecten of some authors) Patinopecten. Moreover, they question- many species have been described from ably referred the Japanese Peden yama- the Tertiary and Quaternary forma- sakii YOKOYAMA and Pecten tryblium tions in the West Coast of North Ame- YOKOYAMA to Pecten (Patinopecten) rica. but whether all of these species healeyi ARNOLD, a Pliocene species of can be referred to Patinopecten or Lituya- California. pecten may be open to question. Judging From the study of the Recent and from the published descriptions and fossil Californian scallops referable to figures of the species hitherto referred Patinopecten caurinns (GOULD), the type to the genus Patinopeeten from the West species of the genus Patinopecten, the Coast of North America it seems that following features must be added to the all may be identified with the genus. descriptions by DMA.. and GRANT and but further study on the problem ap- GALE : pears to be desirable. Rather thick, conspicuous auricular The genus Pecten has nearly the same crurae along inner margin of auricles characteristic features in the hinge area with a conspicuous, rounded. oblong as those of the Patinopecten, but the -distal denticle at extremity of posterior former can be distinguished from the part, that at anterior part extends ven- latter by its greatly inflated right valve, trally and terminates distally in an ob- concave or flat left valve, distinct in- long, rather obscure denticle in right ternal ribs and much less conspicuous valve : left valve with distal denticle byssal notch. The auricular crurae in 148 Koichiro MASUDA Pecten are rather obscure and very cation. slender in the right valve but in the Among the numerous Cenozoic species left valve they terminate distally in a of the so-called Patinopecten of Japan distinct, rounded, rather oblong denticle only one Pliocene species, the so-called at each extremity of the hinge.