564（52） ON THE NEW FORMS OF PALEOGENE MOLLUSCS・ FROM JAPAN By Katsura OYAMA＆Atsuyukj MIZuNo Introduction During this half century，our informations on the paleontology of Pale． ogene system in Japan have been piled up in voluminous amount through the efforts of many authors．H：owever，there remain yet many new forms of molluscs to be clarified for the progress of this science． Here，the writers will describe among them the following twenty－one new Oligocene forms discovere4from the various areas of Japan。 New genus T名o癬伽σOYAMA et MlzuNo，gen．noマ．（in Buccinidae）． New speeies and subspeeies （The names of systems show those from which the holotype occurred） 鰯。％ol伽醜6h露OYAMA et MlzuNo，sp．nov．（Setogawa group） Cα妙加oσso驚h伽s乞30YAMA et MlzuNo，sp。nov．（Wakkanabe formation， Ishikari group） Sゆh。磁幡h伽伽αOYAMAetM・zuN・，gP。n・v．（Akabiraf・mati・n，lshi－ kari group） Sゆho鰯齪『銘吻o航σOYAMA et MlzuNo，sp．nov．（Maze formation，Nishi－ Sonoki group） ．P蜘40卿7ゑsso嬬乞6sα彦漉OYAMA et MlzuNo，sp．nov。（Shioda fomation，：Nishi－ sonokigroup〉 Sαoo61痂hoh履40θ鯉蛤OYAMA et MlzuNo，sp．nov．（H：iragishi formation，Ishi一． karigroup） ノ46吻（Tグ繊鰯吻）照9σoづOYAMA et MlzuNo，＄P．nov．（Kishima∫ormation， Kishilna group） ∠46伽（∠46珈）sh珈oッα卿碗OYAMA et MlzuNo，sp．nov．（Akabira formatiqn， Ishikarigroup） 琢伽s耀傭h露OYAMA et MIz口No，sp。nov，（Omagari fomation，Ombetsu group） L吻σ（ノ406吻）s翻6shJ吻漉OY春M：A et MlzuNo，sp．nov．（Setogawa group） Os舵σ60吻吻7乞s OYAMA et MlzuNo，sp．nov．（Shitakara fomation，Urahoro group） 、C郷s傭ll露6s（C鰯sσ！611づ姻為o吻04σz OYAMA et MlzuNo，sp．nov．（Maze foma－ tion，，Nishisonoki group） 1一（589） 1，ド 塁 彰 ！l 地質調査所月報（第9巻第4号）’ I 旨 ＼ 唱伽6惚吻（qソ・Z・・4勲）h岬肋OYAMAetMIzuNq・sp・n・蝋Eigiref・rma－ 1』』 tion，Nishlsonbki group） 1． 、．L％伽o卿σ郷g襯OYAMA et MlzuNo，sp．nov．（Yamaga formation，Ashiya 旨 group） 巨一r 卜 』丁勿σsづ解（co％ohoo8z8）わ乞sθoiαo卿礎痂QYAMA et MlzuNo，subsp・nqv・（Akabira 1∴ 1・， formation，Ishikari group） 1、1 1「』 ．P吻7s吻oh加sづs OYAMA et MlzuNo，sp。nov．（Wakkanabe formation，Ishikari 1’「 1』、 group） ．」R6吻Zo耀づ卿鰯OYAMA et MlzuNo，sp。nov．（Tokuman formation，Nishi． ノ 1、、， llF sonoki group）・ いア iNew names ド ・αzso舵脚（αzso舵卿o餌sP）πσg伽OYAMA et MlzuNo，nom．nφv．（for助づ60一 ％∫z仰z sP・rndet・NAGAo，1928） 1 1「1 ’，y6彫 7加癬σ（（加Jooπ名伽）ツoた砂翻碗OYAMA et MlzuNo，nom．nov．（for76刀碗一 〇σ擢㍍60％ψ紹ssσYoK6YAMA，1890） 1； 14 ，伽9灘惚伽σ脚OYAMA’etMlzuN・，n・m・n・肌（f・r伽・g燃麟 気に MAKIYAMA，var．6伽8伽NAGAo et INouE，一1941） 1、 Materials・of new species and忌ubspecies are all kept in the Geological 1ピP Depart卑entlGe・1・3ica1Survey・fJapan，except．th・se・fα磁…（αz3・一 瀦卿o囲s7）郷9襯OYAM：A et MlzuNo and S伽θIJαho勲痂oθ競s OYAMA et MlzuNol th¢formerispreservedin the GeologicalandPaleontologicalInstitute， Tδhoku university，and the latter is in the collection of the GeQlogical and Mineralogical I耳stitute，Hokkaid6University♂ Sy’stematic Description GASTROPODA Family Trochidae Ge加s M：inolia A．ADAMs，1860 醜％oZ宛魏6h露OYAM：A et MlzuNo，sp．nov． （Plate I，figs．1a～c） Holotype：GSJ．Reg．No．5008（lntemal mould，somewhat broken at 尭he apical and apertural parts） Type locality二IIn the vicinity of Ashikubo，Miwa－mura，Abe．gm， Shizuoka－ken．（Setogawa group） Description：Shell sma11，turbinate with four whorls，suture distinct．3 B・dywh・rllargeli尊Hated，sculpturedwithab・utninespiralribsandwider interspaces with one week stria on every one；whorls of spire sculptured 『withab・ut・eig与tspiralribs；aperturesupcircular，6・1umellathickened。 Dimensions of the holotype：Height ca．0．85mm；diameter of the last whor10．84mm Comparison：This lnew sp㏄ies somewhat resembles磁物1毎f観蜘Zα如 2一（590） OntheNewF・rms・fPale・geneM・11us6sfr・mJ寧pan（K・Oyama＆AMizun・） YoK：oYAMA，1890，upPer Oligocene species from Central Hokkaid6，but differs from the latter in having more slender whorls and fewer spiral ribs on body whor1．Further，it differs from磁●％ol宛s％み伽g1％鰯σKuRoDA et HABE，1952 in having fewer whorls． Geologic range： （寿ower P）Oligocene Geographic distribution： Cent士al Honshi】 、 Family Epitoniidae Genus Cirsotrema M6RcH，1852 Subgenus Cirsotremopsis THfELE，1928 α駕o舵脚（C魏o舵窺ψsJsP）照9襯一〇YAMA et MlzuNo，nom。nov。 （Platel，丘9＄』18a～c） ユ928，ゆ∫！o％伽吻sp．indet．NAGAo，Sci．Rep．，T6hoku Imp．Univ．，Ser． 2，Vo1．12，No．1，p．93（83），p1．15，fig．7． Descriptioh and locality are given originally by NAGAo（1928）。 H：010type： IGPS．Reg．No．36183（broken in the apical part of she11） Type locality：“Beach rocks，west of Hachiman－zaki，Wakita，Waka－ matsu－shi，Fukuoka－ken”（after NAGAo，1928）． Description： “She11．rather sma11；probably high－turreted，penultimate whorl being slightly narro｛ver than the body whorl and slowly increasing in diamete士down－ ward；suture distinct and deep． E貧ch whorl corlyex，10ngitudinally ribbed and spirally striated；ribs9－10in血umber，rathernarr・w，slightly・blique，sharp，Pτ・mine写tand disc・nti且u・usfr・m・血ewh・rlt・thenext，withtheinterspacesHat・and，孕1m・stthrice 、as broad as the ribs；two or three ribs very broad，thick，and roundly flat on top， gr。wingt・sm・・thvaricesspiralstriaeHne，andcr・wded，eachaltematedwith・neo「 two finer striae．Body whorl rather sma11；base smooth and pro▽ided with a bounding kee1；aperturesma11，subcircular，andsurr・unaedbydisc・孕tin“・usthickenedlips；no defined umbili、cus．” （after NAGAo） Geologi¢range： 76駕蛎αz短宛∂6sあ渉o躍6s zone（upper，01igpcene） Geographic distribution： Northern Kly丘sh廿 Family Calyptraeidae Genus Calyptraea LAMARcK，1799 C吻伽α6α’so鰯h伽sJs OYAMA et MIzuNo，sp．nov． （Plate I，figs．6a，b） H：010type：GSJ．Reg。No．5030 Type1。cality：Nai6－machi，S・rachi－gun，H・kkaid6（exactlyunkn・wn）・ （Wakkanabe formation，Ishikari gtoup） Descripti・興：She111arge，with、threewh・rls；sutures・bscurαSpi「e hlgh，m・re・rless・blique；apex、bluntAperturelargelvery・blique・・nea「1y circular．Surface of the shell om＆mented by many伽Q growth・1ines． Dimensions of the holotype：Height ca10mn玉l major dlameter of body whor129。5mm 3一（591） 地黄調奪所・月報（第9巻第9号） Comparison：This new sp㏄ies is characterized by its high and．oblique3 spire， a箪d is easiIy distinguished from tヒe known species of other forms． Geologic range： Lower Oligocene鞠 Geographic distribution： Central Hokkaid6 Buccinidae Genus Tromi血ina OYAMA6t MlzuNo，1958，gen二nov． Type species： 。肋6乞s伽oZ砂客sノψo吻6％5TAK：EDA，1953 She11℃omparatively large，rather thin，fusiform，withhigh spire。Whorlsl rather high，not v6尊numerous in number with two prominent keβ1s，one ofり which is situated almost on the lower suture． Body whorl generally with two keds as ln T吻hoケo吻ε，but the lower one rarely obsolete． Spiral sculpture except keels and axials not prominent』 Aperture ova1，wi画short canaL Thlsロew genus differs from！▽のi％彫σR6DING，1798，with high spire・ and two（or one）keels． α伽砂6g窺σGRANT et GALE，1931P has two keels，、 butb・th・fthemaresitua㌻eゆthesubsutufalpart・fwh・r玉s． This gellus contains following speci¢s： 24％oぎsケo陀舞sノのo窺謡s TAKEDA，1953 ／1／zoお伽o形力乞s hoた々σ躍oαzs乞3HAYAsAKA et UozuMI，1951 ノ知z砿5朗oムゆ乞sゑsh〃診召妬6駕sゑs H：AYAsAKA et MATsul，1951 且7zo客5伽ol砂乞s房oozゴσ如HATAI et KoIKE，1957 ／ 醜伽8召郷研gσs伽αYoKoYAMA，var．卿わ爾6競s H：AYAsAKA et MA一一 TSUI，1951 1， ・ 醜醜92襯催9αs蜘αYOKOYAMA，1932・ ハ吻脇彫召％卿わ611ケ翻郷乞s且AYAsAK：A et UozuMI，1954 ハ彰ゆずz〃z6σo／z％σJoσYoKoYAMA，1932 Pハ吻劾彫α6zoσnσTAKEDA，1953 Genus Sip弛on．alia AビADAMs，1863 Sゆho7zσ1伽ゑsh貌σ7宛鴛σOYAMA et MlzuNo，sp．nov． （Plate I，丘gs．7a，b，8，9a，b，10a，b）， Holoty’pe： GSJ．Reg．No．5031 Type locality：Upstream of the Tan名an river，Ashibetsu．shi，Hokkaid6．、 （Ak：abira formation，Ishikari group） Description：Shel1，smail to medium in size，with four or five whorls l spire low，slightly concave。conica1，each whorl shou1dered and strongly nodose；apicaユangle about seventy de喜rees． Body whorl large，with thirteen sharp nodes on its upper portion；whorl inHated below the nodes，abmptly［ d㏄reasing the inHation about at anterior one一だhird of the whor1，making「・ very weak ridge between。Whorl of spire angula‡e昼with about thirteen nodes at about閣its middle．Spiral cords regularly arranged in altemation ofl 4一（592） ，当 On the New Forms of Paleogene Molluscs from Japan（K．Oyama＆A．Mizuno） 』4the strongs and weaks，u阜dulated，crossing，with very weak axial ribs l sculpture from the middle to posterior one－fourth of body whorl being very weak：．Aperture obli（1uely ova1，angulated on the upPer，part．CanaI short， nearlystraighl・butthedetailisunkn・wnduet・theill－preservati・n・fshe1L Dimensions of the holotype： Height ca．19．7mm l width of body 『whorl ca．11．9mm l height of body whor1’ca，15mm． Comparison：Sゆh卿召1伽づshJh4吻照n．sp．d近ers from S。3罐盈％舷 MlzuNo，1954，in having many smailer nodes on each whorl and peculiar ・〈）mamentation of body whor1。It so；newhat resembles S．αsα肋郷o％sぱs（NAGAo）， 1928，but the latter has few nodes on the whorls and higher she11。 Also，it Tesembles American S．わ加伽α如 DlcKERsoN，1915and its allies，but it ・differs from、the American forms in having much inHated body whorl and wellde丘nednodeson』eachwhor1． Remark：The neW species are sor践etimes found in the Akabira and －Wakkanabe formations of Ishikari group．on the northem part of the Ishikari ・coa1丘eld，in Central Hokkaid6，together with such brackish molluscan fossils， 、as Os舵α，Co癖o漁and段not無6r allied spegies，一Sゆho禰1毎sα肋肋瑠MlzuNo・ This new species may be classed in a new subgenus of Sゆho照1伽associate4 with S．s盈罐％名痂：their morphologic characteristics，namely，the short and nearlystraightcana1，and1・wspire・suggest，貧sわ・inted・utbyM・zuN・ （1954），their similarity to the species of Eo吻ho郷1乞α，but『6ur瀕materials can 、be apparently distinguished from the species of the subgenus in having箪o distinctbiangulati・n・fb・dywh・r1；theydi鉦ergfr・mth・sす・fNσss鰯σin lhaving nearly straight and hardly bent cana1． Geologic range：Lower Oligocene Geographic distribution： Central Hokkaid6 Sゆho照1齪吻φo％加OYAMA et MlzuNo，sp。nov。 （Platel，丘gs．2，3）辱 1928，C㈱061如吻～sp．indet．d．NAGAo，Sci．Rep．T6hoku Imp．Univ．， Ser。2，V・L12，N・・1，阜122（112）・P1115」gs・42～44・ Holotype： GSJ．．Reg．No．5035 「Type locality：In the sample of “：Kita－tatek6” at the Sakito coal mine，Sakito－machi，Nishi－so血ogi－gun，Nagasaki－ken。（Maze formation，Nishi．