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 Peden ed to be one of the important and in- based upon a Northern Californian scal- teresting , 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 of Patino- by KURODA (1932) as a subgenus of based upon a Recent . 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 , 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 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. From the Patinopecten tokunagai (YOKOYAMA). has morphological characters it is evident the same characteristic auricular crurae that Patinopecten should be included into as the true Patinopecten, though it is the same subfamily Pectininae as the more obscure. The other morphological genus Peden. characters of tokunagai are so different In the genera of Amusiinae the auri- from the Patinopecten of North America cular crurae terminate distally in a very that it can be regarded as an undes- much conspicuous, rounded, rather ob- cribed genus of the Patinopecten group long denticle at each extremity of hinge as mentioned later. and they are considered to be one of In other species of the so-called Pati- the most important characters in the nopecten of Japan the characteristic fea- classification of them besides the in- tures of hinge area as tokunagai have ternal ribs (VERRILL, 1897). not been observed. The other genera Considering from the morphological or subgenera of the Japanese Patino- characters of the auricular crurae above pecten group in broad sense. that is to described it is evident that they enable say. Forlipecten, Masudapecten and Ko- the valves to resist the powerful action torapecten are lacking in the character- of the adductor muscle when suddenly istic features of hinge area above men- closed and may serve to strengthen tioned. the valves. This consideration may be supported by the abraded distal denticle Revision of the Japanese of the auricular crurae in the left valve Patinopecten in usage of full grown specimens of the genus Peden, because this was probably pro- As noticed in the earlier pages, among duced by the friction of the valves the species hitherto referred to Patino- when suddenly closed for swimming or pecten in Japan the true Patinopecten for self-protection. Thus the above group is represented only by the so- noticed features of hinge area are im- called Patinopecten tokunagai t (YOKO- portant criteria in the classification of AMA). whereas the other scallopsY of the Pectinidae. the group should be referred to some The genus Patinopecten in usage in genus other than Patinopecten. From Japan very much resembles the true the morphological features, among the Patinopecten in general exterior features. Cenozoic Pectinidae of Japan only Pecten However, almost all species of the so- albicans (SCHROTER), Peden excavatus called Patinopecten of Japan can be dis- ANTON. Pecten punculatus DUNKER tinguished from the true Patinopecten and the so-called Patinopecten tokunagai by lacking the auricular crurae with (YOKOYAMA) can be included into the conspicuous distal denticle, rounded subfamily Pectininae. radial ribs in the right valve, very Since publication of a monograph of shallow byssal notch and large auricles. the Pectinidae of Japan (MASUDA, 1962a), Therefore, the Japanese species of Pati- the writer, from the evidence accumu- nopecten are in need of a new classifi- lated to date, finds that the Patinopecten 461, So-culled Patinopecten. 149 group must be revised and proposes in Mizuhopecten kimurai mmurayamai this work the following classification of (YOKOYAV A), 1926 the Japanese Patinopeclen group. Mizuhopecten kimurai nakosoensis (MASUDA). 1960 Mizuhopecten kimurai liganouraensis Family Pectinidae (NAKAMURA). 1940 Mizuhopecten kimurai ugoensis (HAT AI and Subfamily Pectininae NISIYAMA). 1939 Genus Pecten MULLER, 1776 Mizuhopecten kimurai yudaensis (MASUDA), (SCUROTER), 1802 1960 Pecten naganumanus YOKOYAMA, 1920 Mizuhopecten kobiyamai (KAMADA). 1954 Mizuhopecten kudoi (NOMURA), 1935 Genus Yabepecten MASUDA, n. gen. abepecten tokunagai (YOKOYAMA),Y 1911 Mizuhopecten paraplebejns (NOMURA and TAI), 1936 HA Subfamily Fortipectininae MASUDA, n. Mizuhopecten planicostulatus (NOMERA and subfam. NIHNO). 1932 Genus Fortipecten YABE_and HATAI, 1940 Mizuhopecten poculwn (YOKOYAMA), 1926 Fortipecten kenyoshiensis (CHINZEI), 1960 Mizuhopecten pocnlum tsudae (NODA). 1962 ortipecten tkahashii (YOKOYAMA), F 1930 Mizuhopecten togeshitensis (AKIYAMA). 1962 Mizuhopecten tokyoensis (TOKUNAGA). 1906 Genus Masudapecten AKIYAMA . 1962 Mizuhopecten tokyoensis hokurikuensis asudapecten iwasakiensis (NOMURA).M 1935 (AKIYAMA), 1962 MasudapecteN kintaichiensis (MASUDA). 1958 Mizuhopecten tokyoensis sematensis Masudapeten masndai (AKIYANIA), 1962 (AKIYAMA), 1962 (JAY). 1857 Genus Kotorapecten MASUDA, 1962 Mizuhopecten yessoensis nakatombetsuensis Kotorapecten egregius (ITOIGAWA), 1955 (AKIYAMA), 1962 Kotorapecten kagamianus (YOKOYAMA). 1923 Mizuhopecten yessoensis pseudoyessoensis Kotorapecten kagamianus moniwaensis (AKIYAMA and MIYAJIMA). 1960 (MASUDA), 1958 Mizuhopecten yessoensis yokoyamae (MASUDA). Kotorapecten kagamianus nimaensis 1962 (MASUDA), 1958 Kotorapecten kagamianus permirus Genus _Nipponapecten MASUDA, 1962 (YOKOYAM.a), 1926 ipponopecten akihoensis (MATSUMOTO).N 1930 Kotorapecten uaganoensis (MASUDA), 1962 Nipponopeclen wakuyaensis (MASUDA). 1956 Kotorapecten nakajimai (MASUDA), 1954 Kotorapecten sannohensis (CHINZEI), 1961 asudapecten, Kotorapecten and Nip-M Kotorapeclen tryblium (YOKOYAMA). 1925 ponopecten which are previously des- Kotorapecten trYblium shinshuensis cribed as subgenera (AKIYAMA, 1962 (AKIYAMA), 1962 MASUDA, 1962a) are raised to generic Kotorapecten yamasakii (YOKOYAMA), 1925 rank because of their morphological Kotorapecten yamasakii ninohensis (MASUDA), characters which bring them to the 1954 level of genus. Genus Mizuhopecten MASUDA, n. gen. izuhopecten chichibnensis (KANNO). 1958M izuhopecten hashimotoi (AKIYAMA), M 1962 Description Mizuhopecten ibaragiensis (MASUDA), 1953 Genus Yabepeeten MASUDA, n. gen. Mizuhopecten imamurai (MASUDA). 1959 zuhopecten kanbaraeusis (OTUKA). Mi 1938 Type-species:-Pecten tokunagai YOKO- izuhopecten kimurai (YOKOYAMA), 1925M YAMA, 1911. Pliocene Koshiba forma- 150 Koichiro MASUDA tion of Kanagawa Prefecture. much more conspicuous auricular crurae. Geological range :-Pliocene. Fortipecten.Masudapecten, Nipponopecten Diagnosis:-Shell large. rather thin, com- and Kotorapecten also can be distin- pressed, suborbicular, inequivalve, right guished from the present one by their valve more convex than nearly flat or lacking auricular crurae with distinct slightly inllated left valve ; right valve distal denticle. with numerous, very low. round-topped radial ribs which are obscure in younger Subfamily Fortipectininae stage but tend to become distinct with MASUDA, n. subfam. growth ; left valve with rather distinct, very slender, low radial ribs which tend Definition :-Shell large to very large. to become obscure with growth and suborbicular ; inequivalve, right valve characteristic, conspicuous network ; an- more inflated than nearly Hat or some- terior auricle larger than posterior, with what inflated left valve ; cardinal crura very shallow byssal notch ; hinge with rather distinct but simple ; ctenolium simple cardinal crura, wide and shallow usually not observed in adult shell but resilial pit with rather distinct lateral sometimes observed in younger shell ; ridges which tend to become obscure auricles nearly equal, moderate to large; towards and auricular crurae which byssal notch wide and shallow ; interior terminate distally in a rounded, rather surface somewhat folded corresponding obscure, oblong denticle; interior surface to external sculpture. slightly folded corresponding to external Remarks:—The present new subfamily sculpture. now includes such genera as Fortipecten Remarks :—The present new genus is YABE. and HATAI, Masudapecten AKIN-A- named in honor of Dr. Hisakatsu YABE. MA. Kotorapecten MASUDA, Nipponopec- Emeritus Professor of the Tohoku Uni- ten MASUDA, and Mizuhopecten MASUDA versity, who founded the Institute of n. gen. among the Japanese Pectinidae. Geology and Paleontology, Tohoku Uni- The present group can he distinguish- versity. ed from the Pectininae or Amusiinae by The present new genus is based upon the inequivalved shell with rounded the Pliocene Peden tokunagai YOKO- smooth radial ribs, nearly equal auricles AMA. The genus Patinopecten canY be with wide and shallow byssal notch, no distinguished from the present one by auricular crurae with distal denticle and its distinct, squarish radial ribs in the folded interior surface corresponding to right valve, deep byssal notch and external sculpture.

Explanation of Plate 22

Figs. la-d. Patinopeclen caurirnrs (GOULD). la, Right valve, xca. 4/9. lb, Hinge area of la, .•~1 lc. Left valve. •~ca. 4/9. Id. Hinge area of lb, •~1. SM, Reg. No. 10885. Loc.

Puget Sound. Washington. U.S. A. Recent.

Figs. 2-4. Yabepecten tokunagai (YOKOYAMA). 2. hinge area of left valve, •~1. 3. Hinge area of right valve, •~1. DGS, Reg. No. 3714. 4. Right valve, •~ca. 1. IGPS. coll. cat. no.

72542. Loc. Right river cliff of the Chikagawa stream, about 700 m. from the sea shore,

Chikagawa, Mutsu City. Aomori Prefecture. Pliocene Hamada formation. MASUDA : So-called Patinopecten Plate 22

1 a 1 b

2

1 c

3

1 d

MASUDA photo 461. So-called Patinopecten 151

Genus Mizuhopecten MASUDA, n. gen. Remarks

Type-species:-Pecten yessoensis JAY. With regard to the development of 1857. Recent, Northern Japan. the so-called Patinopecten of Japan the Geological and geographical distribu- writer previously noticed that Patino- tions:—Oligocene to Recent. Northern pecten (s. s.) which is newly proposed in Japan. the present article as Mizuhopecten, is Diagnosis :-Shell large, rather thick, very abundant in specific and individual suborbicular, inequivalve, right valve numbers during the Tertiary period, more inflated than nearly flat or slightly but only two species are known in the inflated left valve; right valve usually Pleistocene and only one species, Patino- with rather distinct, broad, rounded pecten (s. s.) yessoensis (JAY) is known radial ribs, rarely dichotomous ; left from the Recent sea of Northern Japan. valve with distinct but low, rounded, Mizuhopecten chichibuensis (KANNo) narrow radial ribs and fine network ; from the Nenokami sandstone of the anterior auricle nearly equal to posterior Hikokubo group, Chichibu Basin, Sai- one, with wide and shallow byssal notch ; tama Prefecture (KANN°, 1957) and also hinge with distinct but simple cardinal questionably from the Taishu forma- crura. wide and shallow resilial pit with tion, Tsushima Island, Nagasaki Prefec- distinct lateral ridges ; interior surface ture (KANNU, 1955; is the earliest known somewhat folded corresponding to ex- species of the genus Mizuhopecten in ternal sculpture. Japan. Judging from its associated Remarks:—This new genus is named fauna the Nenokami sandstone is con- based upon the old name of Japan. sidered to have been deposited under Mizuhopecten can be distinguished the influence of warm thermal conditions. from Patinopecten by its having no Therefore, the ancestral stock of Mizu- auricular crurae with distal denticle. hopecten may be found in the Early rounded, broad radial ribs and large Tertiary formations of a Southern auricles with wide and shallow byssal region. In general, the changes in the notch. From Yabepecten it differs by marine environmental conditions from its having no auricular crurae and broad, the Early Neogene to the Recent are rather distinct radial ribs. Fortipecten well reflected in the mega fauna. The also can be distinguished from the pre- water temperature generally became sent one by its greatly inflated right gradually lower from the Early to latest valve, nearly flat left valve, very large Neogene and showed fluctuation during auricles and narrow radial ribs. the Pleistocene. The decreasing in the Judged from the figures and descrip- number of species of Mizuhopecten be- tion of Pecten (Aequipecten) pseuduloa sides other pectinids from during the EAMES and Cox (1956) from the Upper Tertiary to the Recent may coincide Miocene to Pliocene of Persia, it can be with the gradual lowering of the water distinguished from the present one by temperature associated with physical its left valve being slightly more inflated and nutrient changes in Japan, especially than the right valve. Whether their in Northern Japan. The decreasing of specimen can be referred to Aequipecten pectinids in general with the advance and Pecten may be in need of a re-ex- of geological time can be explained by amination. the changes of environmental conditions . 152 Koichiro MASUDA

The earliest occurrence of the common The occurrence of the genus Palino- Recent species of Northern Japan, Mizu- pecten is unknown from the Japanese hopecten yesoensis (JAY), is from the Miocene or from the Miocene of South- Early Pliocene formations of the Japan eastern Asia. Therefore, its ancestral Sea borderland province (MAMMA. 1962b) stock may not be a migrant from Asia in association with several species of but from some other regions, probably Mizuhopecten and Ybepecten tokunagai from the Mediterranean region. Yabe- (YOKOYAMA). Although Mizuhopecten pecten tokunagai (YOKOYAMA) which ap- yessoensis (JAY) survived to the present, peared in the Early Pliocene of Northern almost all other species of Mizuhopecten Japan probably branched off from the and Yabepecten tokunagai (YOKOYAMA) Patinopecten group of the Northern became extinct at the end of the Early Pacific region of North America as a Pliocene. Mizuhopecten tokyoensis hoku- result of its westward migration from rikuensis (AKIYAMA) appeared in the North America in the Early Pliocene. Early Pliocene but it became extinct at It became extinct during that time. the end of the Early Pliocene and :Mizu- hopecten tokyoensis (s. s.) (TOKUNAGA) which may be derived from tokyoensis References hokurikuensis, appeared in the Late Plio- AKIYAMA,M. (1962) : Studies on the Phylo- cene and survived to the Pleistocene. geny of Patinopecten in Japan. Sci. Rep., Mizuhopecten tokyoensis semAtensis (AKI Tokyo Kyoiku Daigaku. Sec. C, Vol. 8. No. YAMA) appeared in the Pleistocene and 74. pp.63-122, pls. 1-8. text-figs. 1-3. became extinct before the close of the ARNOLD,R. (1906) : Tertiary and Quater- age. The development and extinction of nary Pectens of California. Prof. Pap., U . S. Geol. Surv., No.17. pp.7-146, pls. the species Mizuhopecten may have had 1-53, text-figs. 1-2. intimate relation with the changes of DALL. W. H. (1898) : Contributions to the the environmental conditions. Tertiary Fauna of Florida with special The genus Patinopecten distributed in Reference to the Silex Beds of Tampa the Northern Pacific region may be and the Pliocene Beds of the Caloosaha- closely related to Peden or Amusiinae tchie River. Trans. Wagner Free Inst. considering from the presence of the Sci., Vol. 3. Pt. 4. pp.571-947, pls. 26-37. auricular crurae with distal denticle. EAMES, F. E., and Cox, L. R. (1956) : Some

Explanation of Plate 23

Figs. 1a-b. Patinopecten caurinus (GOULD). 1a. Right valve, •~ca. 1/2. 1b. Left valve. •~ca.

1/2. DGS, Reg. No. 1576. Loc. Eel River. Scotia Bluffs, Scotia, Humboldt County, Cali- fornia, U.S. A. Pliocene Wildcat formation.

Figs. 2a-c. Patinopecten healeyi (ARNOLD). 2a, Right valve. •~ca. 2/3. 2b, Hinge area of 2a, ca. 2/3. 2c. Hinge area of left valve, •~ca. 2/3. DGS. Reg. No. 1128. Loc. Rose Can-•~

on, La Jolla Quadrl., San Diego, California. U.S. A. Pliocene. y Fig. 3. Yabepecten tokunagai (YOKOYAMA). Hinge area of left valve. •~1. DGS, Reg. No. 3714.

Loc. Right river cliff of the Chikagawa stream. about 700m. from the sea shore. Chika-

gawa. Mutsu City, Aomori Prefecture. Pliocene Hamada formation. Figs. 4-5. Mizuhopecten yessoensis (JAY). 4. Hinge area of right valve. •~1. 5. hinge area of

left valve, •~1. DGS, Reg. No. 4488. Loc. Asamushi. Nonai-mura, Higashi-Tsugaru-gun, Aomori Prefecture. Recent. MASUDA : So-called Patinopecten Plate 23

1 a 2b

2c

2a

3

1 b

4

5

MASUiA photo 461. So-culled Patinopecten. 153

Tertiary Pectinacea from East Africa, and California. Prof Paper, U.S. Geol Persia and the Mediterranean Region. Sure., No.354-J. K, pp.225-237. pls. 35- Proc. Malac. Soc. London, Vol. 32, Pls. 1 16. 2. pp.1-68. pls. 1-20. MASEDA, K. (1962a): Tertiary Pectinidae HABE. T. (1951) : Genera of Japanese Shells. of Japan. Sci. Rep., Tohoku Univ., Ser. 2 Pelecypoda. 1 (in Japanese). pp.1-96. (Geol.), Vol. 33, No.2, pp.117-238, pls. text-figs. 1-192. 18-27, text-figs. 1-11. KANNO, S. (1955) : Tertiary from (1962b) : Notes - on the Tertiary Pecti- Taisho Mine, Tsushima. Nagasaki Pre- nidae of Japan. Ibid., Spec. Vol. No. 5, fecture, Japan. Trans. Proc. Palaeont. pp. 159-193. text-figs. 1-9, tables 1-9. Soc. Japan. .V. S. No. 18, pp.31-36. p1.6. VERRILL, A. E. (1897) : A Study of the text-fig. 1. Family Pectinidae. with a Revision of -(1957) : -(1957) On Some New Species of Pali- the Genera and Subgenera. Trans. Conn. nopecten from the Chichibu Basin. Sal- cad. Arts & Sci., Vol. 10, pp. 41-95,A pls. tama Prefecture. Bull. Chichibu .Mus. 16-21, text-fig. 1. at. Hisl.. No. 7, pp.101-108, pls. 1-3.N YABE, H., and HATAI. K. (1940): A Note on KURODA, T. (1929-1935) : An Illustrated Pecten (Fortipectcn, subgen. nov.) taka- Catalogue of Japanese Shells (in Japa- hashii YOKOYAMA and Its Bearing of the nese). Parts 1-16. Venus, Vols. 1-5. Japanese Neogene. Sci. Rep., Tokoku Append.. pp.1-154. text-figs. 1-165. mp. Univ., Ser. 2 (Geol.), Vol. 21. l No.2, MACNEII., f.S. (1961) : Lituyapecten (New pp.147-160, pls. :34-35. Subgenus of Palinopecten) from Alaska

Asamushi it •ó’Ž Koshiba •¬ŽÄ Chikagawa ‹ß•ì Nonai-mura –ì“à‘º Higashi-Tsugaru-gun “Œ’ÃŒyŒS