For His Criticism and for Reading the Manuscript. . MIOCENE

MIOCENE FORAMIiNIFERA IN CHUGOKU, JAPAN

. By Shigeo MURATA*

Abstract: No one has ever reported on the smaller foraminifera in the Miocene sediments of Chugoku, Japan. The writer discovered it in the Tortonian, the Helvetian and the Burdigalian in the Miocene of Chugoku. Here, the writer wants to present some of his researches concerning the stratigraphical, micro' paleontological and paleo-ecological significance of tho Miocene foraminifera in this district. The new species is described.

INTRODUCTION The Miocene sediments in Chugoku, hitherto, have heen investigated in ¥detail on the stratigraphy and paleontology, except on the foraminiferology. Since his micropaleonte- logical study have been tried on the Miocene formations in the vicinity of Matsue City, shimane Pref., the writer has started on some researches by the foraminifera in the Miocene of Chugoku. In the present paper, the Miocene foraminifera . frem Chugoku and their stratigraphical, micropaleontological and paleo-ecologicql significances are dealt with. These were collected by the writer from l951 to 1953, and are now kept in the cellection of the Mining Department, . Kyushu Institute of Technology. Here the writer would like to express his cordinal thanks to Dr. K. Asano of the Inst- itute of Geology and Paleontology, Tohoku University, Sendai, for his kind advices and comments, and Prof. G. Imamura of the Institute of Geology, Hirds' hima University, Hiro¥ shima, for his 'kind encouragements and suggestions given to the writer to the present study. He is particularly grateful to Dr. S. Jizaimaru of the Kyushu Institute of Technology for his criticism and for reading the manuscript. . ' MIOCENE STRATIGRAPHY OF CHUGOKU ¥' The inVestigation of the Miocene stratigraphy in Chugoku has made very great progress, ewing to the researches done by Dr. Y. Otuka, Dr. T. Tomita and G. Imamura and hi$ fellows. By these recent studies, the Miocene stratigraphy in thig di$trict has heen estab- lished as shown in Table 1. The Kimitani, the Naheyama and the Yatadani group deyeloped aleRg the coast frenting the Japan Sea in Chugoku, and the lower member of the Miyoshi and the Katsnta group . in the Miyoshi and the Tsuyama basin among the mountains of the aferementiosted district are the coal bearing formations which censtitute the Kimitani, the Shimane, the Kekubu} the Futami and the Tsuyama coal field, respectively. The Koura series, including the above mentioned group, consists mainly of sandgtone,

*Mining Department, Kyushu Institute ef Technology, { 64 shigeo Murata

shale and conglamerate with intercalated lignites, which contains the comptoneipdyllum- ttguidamber flora, a characteristics of the Burdigalian, lying uneonformal)ly above the Paleozoic, tihe gneiss, the granite and the quartz-porphyty etc. As to the geological age, the terrestrial sediments just eited, unconformably overlain by the Opercude'na-Miogypsincb-Vicarya zone mqntig.necl belQw, may be, ¥assigned to the lewe; Burdigalian, the lower Miocene. Th,q Tany}azukuri serieg includes the upper shale and the lower sandstone and conglome-. rate member with the 0perculina-Miogypsina-Vicarora fauna, which contains the tuff zone in the middle part. The sediments corespond to the Tamazukuri series in Hiroshima and Okayama ' Pref. have the aforementioned fauna, while in the Tamazukuri group and its equivalent formations in Shimane and Yamaguchi Pref. developed along the coast of the Japan Sea this fauna have not been found. The Iast mentioned sediments, however, included the characteristic species of the Opmczslt'na-IMogypsina horizon in Toyama PreÅí, namely Siraton'a siratoriensis (OT(JKA), Thptasira n. sp. and Venenicardia (Cptclocardia) n. sp. etc., and also the same species as that of the Miyoshi ' and the Tsuyama btisin, namely &'ratoria siratoriensis, Pecten kagnnzianus and Pecten kimurai etc. Therefore, the last ment! ion'ed group may be correlated with the Operculina-Miogorpsina zone. There has been found E'thothamm'um ramosissiumum REuSS, a characteristics of the Miocene of Japan, in the Kaw'ajiri formation, ' the upper member of the Yuyawan group equivalent to the ahove pieriti'oned group. ' - Judging from the similarity of these faunas, the intercalation of the tuff in the middle part of these sediments and the change of the deposition indicating the same transgressien stBge in each group, the Tamazukuri series may be referred to the upper Burdigalian in the'European standard.. These marine groups include the great number of the foraminifera mentioned,s. below. ' L T,he Fujina series in S'himane Pref. consists of sandstone, shale and conglomerate with the so-called ""Fujina fauna", a characteristics of the Tortonian of Japan, uneonfoimably lying above the Omori series mentioned below. Desmostylus 1'apombus TOKUNAGA, found , inahorizonalttle higher than the 0perculina-Miogypsiua horizon in Japan, has been discovered in the 'lower Fujina series near Wakayama, south of the Shinzi Lake, Shimane PreÅí The Fujina series, therefore, is marine in origin, and may be correlated with the Tortonian. The Omori series in this district consists of basaltic, liparitic and andesitic rocks and their pyroclastics with intercalated sandstone and shale with a few foraminifera. The Omori Series which Iies between the Fujina and the Tamazukuri, therefore, may be referred to the Helvetian'stage. The Matsue series, the uppermost Miocene in Chugoku, unconformably lying above the' Fujina geries, consists of shale, and sandstone with intercalated basaltic rock and it's pyroclastics with the molluscan faunule. This series belongs to a shallow water facies, arid' may be 'referred to 'the Sarmatian, the upper Miocene. The complete Miocene formations are .the Shinzi group in the Shimane Peninsula, -- MJ'oeene Foraminifera ¥i Chugoku, Japan 65 S"himane Pref. It has been said that the Shinzi' group, thickness up to 2ooem., had been depesiKed in the se-called ""Shinzi geesyncline" during the Miocene age in that area. By his rece'nt stratigraphical and paleontological $tudies, Y. Tai referred the Koura sandstone, the Josoji shale, the Ushikiri alternation, the Furue mudstone and the Matsue sandstone formation in this group approximately to the lower Burdigalian, the upper Burdigalian, the Helvetian, the Tortonian and the Sarmatian stage respective!y.

MIOCENE FORAMINIFERA IN CHUGOKU

The Miecene fossi'1 remains of the smaller foraminifera in Chugoku were found by the writer in three stages, namely the Tortonian, the Helvetian and the Burdigalian. The T6rtonian foraminifera was collected from the Shimane Peninsula, the vicinity of Matsue City, the southern area of the Shinzi Lake and lzumo City in Shimane Pref. These distriets include the .following species. Cyelammiua caneelZata BRADy vr C. incisa (STACHE) r 'C. 7'apaiNkra AsANo c C. erbiczslan's BRADy r . `' '' Haplophragnicles cornpressam LFRoy c 4 H. renzi ASANO' f Trochammina mobensis AsANo vr 'Mastinottiella commune's diORBIGNY c Plectina sp. ' ' r Gaucbyt'ua sp. , r QitangzseZoculina sp. vr. lagenonodosaria scaim's (BATseH) vr Nedosaha sp. , vr Eponides pp. vr Anomaliua sp. vr Among them, Cyclamunv'na irutsa, C. orbicularis, C. pasigla, C. (xmcezatua, C. ]'aporNeca, Haplophragmoides compressum, H. renzi, Trochamnina nebe7ut's and MavtinottieZla communis are the characteristic species of the Miocene in JRpan. The abundant occurrence of

Cptclammina ]' aponica, C. pasiZla, Haplophragnoictes campressum, H. rend and Martimottiella communis has been reported in the Tortonian sediments of Akita, Niigata and Toyama Pref. etc. These may be considered to have been affected by the colder Kurile current (er Oyashiro-current). And alse this assemblage hag very great number of the apenaceous 66 - ¥ Shigeo Murata forms, namely C.ieclammina, llapZophragmoides, Trechamm'ua and MartinottielZa etc., and few calcareo"s forms, such as Lagenonedes(uria and ATmbsan'a etc. Desmostylus ]'apani(xss ToKVNAGA, a colder water species in Japan, has been discovered in the vicinity ef Wakayama, south of the g. hinzi Lake. Judging from these facts, it seems reasonable to conclude that the Tortonian age must have been under the influence of the colder KuriIe current in the abeve mentioned district. This conclusion harmonise well with that from the study of the molluscan faunule by Y. Otuka and Y. Tai. The foraminifera of the Helvetian age has been discovered very poorly in the Shimane Peninsula, the southern area of the Shinzi Lake and Izumo City, Shimane Pref. These are only two following species, which aTe rarely found and only the arenaceous form. Cyclamnziua incisa (STACHE) r

As already stated, the Omori series in the Helvetian consists of basaltic, liparitic and andesitic rocks and their pyroclastics with intercalated sandstone, shale and conglomerate. In the Helvetian, an intense volcanicity took place in the above mentiened district, probably along the present coast of the Japan Sea in Chugoku. The above mentioned facts have been recognized also in Akita Pref. and Hokkaido ete. These suggest that the larger form Cyclammina prefers an abnormal condition due to the volcanic activity. Judging from these facts, it may be concluded that the Helvetian sediments in this dis- ' trict indicate a colder water condition affected by more intense volcanicity than that of the Tortonian age. The Burdigalian foraminifera were found numerous in Chugoku, which may be divided into three types aS follows. The first assemblage of the Burdigalian was discovered by the writer from the Miyoshi and the Tsuyama basin among the mountains of Chugoku. These consists of the following specles. .

Gole'sella scheneki AsANo f , Martinottiella commune's dJORBIGNy vr PseutogauclrÅrtina ishikiensis AsANo c P. nt'igataensis AsANo vr Sigmoilina schlumbergert' STLvEsTRI vr RobuZus lieciaus (CusHMAN) c R. nikobarensis (SCHwAGER) vr R. pseitclorotulatus AsANo vr VagT'nuliua chugokuensis MuRATA n. sp. c zlfargt'nuZiua sendaiensis AsANo r. LagenomoclosarL'a horugaensis (OTNoMmADo) vr L. sagama'ensis AsANo vr Miocene Fora,ininifera in Chugoku, Japan ---- 67 ,L. ' scaZaris (BATscH) ' vr Nedosaha raphaua (LINNE) ' vr LlentaZina emaclata REuss r D. cf. .fiililtTornzis (D'ORBIGNy) vr D. " ¥ subsoZuta (CUSHMAN) c EZk'psomoaosan'a sp. vr Lagena sthata (DtORBIGNY) vr Cuttulina sadoensis (CVsH.MAN & OZAWA) vr G. Z(uctea (WALKER & JAcoB5 vr iVonv'on iaponicum AsANo f AT. asamoi (MURATA) vr Bulimina cÅí inJfZata SEGUENzA' vr Uvigen'na subperegriua CUSHMAN & KLEINPELL c (lyroidi,ua orbicuZaris DtORBIGNY vr Rotalia inLIFZata (SEGVENZA) c Eponides fiigidus (CusHMAN) f E. haiaingen' (D'ORBIGNY) f' E. orientalis AsANo 'vr E.. praecinctus (KARRER) f Baggina philippiensis (CusHMAN) vr Anomah'ua flintii CusH]!fAN vr

Among them,¥Globigeriua Goesella schencki, Pseze(lbgandryina sp. ishikiensis, f P. niigataensis, Vagr'nzalina chugokuensis, Marginulina sendaiensis, Uvigen'na subperegn'ua, Aronion asumoi and Epenides praecinctus are the charaeteristics ef the Burdigalian species in the Miocene of Japan. Furthermore, this assemblage includes the abundant species of the Lagenidae and few pelagic forms, and has alse the follewing forms as the speeies flourished luxuriantly in the warmer water condition oftthe Pacific Ocean type. ]7aginulina chugokztensis MuRArrA, n. $p. Lagenono(losaha hyugaensis (OINOMIKADO) Dk,ntalina cf. fclbltrorma's (D'ORBIGNy) RetaZia inj(Zata (SEGUENzA) EponL'aes haiclingeni (D'ORBIGNy) E. praecinctus ,(KARRER) E. orientalis A.sAtsTo Baggr'na philippiensis (CUSHMAN) Anemalina fZintii CusHMAN Judging from the above mentioned facts, the writer wishes to conclude that this assemblage may indicate the warmer condition of an island sea type. This cenclusion may be 68 ¥ 'j---2-"Shigeo -Mtirata ;' ' , more confumed by the occurrence ef the Operetdiiua-Mrtogrypana-Vicaya fauna, the warmer species of the Burdigalian,'in this foraminifera-bearing sediments. ¥i' The Burdigalian assemblage of the second type was found bY the writer at Takuno in the Omori distriet, Shenzejiki in the Kokubu disniet and the southern area efMasuda City in the Masuda district etc.' These are the following gpeeies. , Comuspira sp. ' vr Gardryina ogasuensis AsANo vr, Gaztclryinella J'aponica AsANo vr Haplephragmoi(les carnpressum LERoy' vr H. rengv' AsANo ' '¥ vr H. ' cf. rmlde'ssatum (BRADy) .r

Cn'brostomoides k)tashieense AsANo ¥ vr, Cyclammiua incisa (STACHEÅr f C. 7'aponica AsANo ¥ vr C. pusilla BRAT)y vr Quimpelogzeliua sp, vr Robulus lu6idus (CvsH!leAN) f

Vage'nulina chugoleuensis MuRATA n. sp. r MarginuZina sendaienst's AsANo ¥ vr M. glabra DtORBTGNY vr. ' Lagemonedosaria ¥saganimsis AsANo '' r S L. scaZaris (BATscM) f '

Llentalina smbsoluta (CUSHMAN) ' vr Ellt'psomoclbsaria sp. vr Polymorphinidae f Aronion 7'aponicum AsANo c IV. asanoi (MURATA) r Elphidium hit+ghesi foramimosum CUSHMAN vr

Uvigeriua subperegn'na CUSHMAN & KLEINPELL vr Gyroiaiua orbiculan's DtORBIGNY vT Rot.rv.lia inLfZata (SEGUENZA) c

Eponides praecinctus (KARRF.R) a Miocene For&minifera ¥,in Cltpgoku, Japan 6¥9 Baggt'na sp. vr '' 'H(muawaia tagaeTbsis AsANo ¥ f H. ne'ppom'ca AsANe c i Cibicr'des lobastulus (WALKER & JAcoB) vr ''.C cf. refuZgerzs (MoN'rFoRT) vr

Among them,CZobigen'na the characteristics of the Burdigalian Spp. foraminifera f in Japan are as follows. Haplophrugmoides compressum LF.RoY H. rennt' AsANo 'Cptclamnzina incisa (STACNE) C. iaponica AsANo ¥¥:¥¥ C. pasiZla BRADy Vaginuliua chugokuensis MuRAI'A n. sp. ''¥MarginuZina serz(kziensis. ¥AsANo / Uvigeriria subperetptna CVSHMAN & KLF,INPF.IJ. IVorzion asamoi (MuRA'1'A) Eponicles praecz'nctus (KARRER) Hangawaia tagaensis AsANo This assemblage is very similar to that of the first type of the Burdigalian of Chugoku jmst ci'$ed, except+the fact that the fQxmer inclu¥des the genus CycZanzrnina and ffaplophra- gmoidkis etc. These two foraminiferal assemblages indicate the same relation as that of the Tsuma and MiyaZaki facies of the Miyazaki group from the Tortonian to the Sarmatian in Miyazaki Pref. ; namely the former is of an island sea type without the genus CycZanwniua, aNd¥-the¥latter is of an open sea type with the genug Cyclame, both of which indicate the' Wamier condition. t' From'the above rnentioned faets, is ¥iseemg reasonable to cenclude that the second foraninifergl assemblage,may indicate the wamer eondition ¥of an open sea in the Burdi. galian¥ $tagef the lower Miocene ; the conGlusion being in harmony with that from the study of the molluscan faunule by Y. sOtuka and G,. Imamura. ,The la$t Burdigalian foraminiferal assemblage in Chugoku was discovered by the writer in{the- $himane¥ P/eninsula ,and tha southern area of the Shinzi Lak¥ e ete. along the coagt of, thq}Japan Sea, except the above ,mentioned district where the warmer. foraminiferal assem. blage of the Burdigalian are found. This foraminifera is of the follewing arenaceous forms.

,,¥i"¥:J'vFj, `¥ Martinoutella IIloTy)thia,sp, commas DtORBg¥GNY,- ,, fvr , ¥.¥." HapZephragnzoides cempressam LE+Roy¥ vr ,t, .,.H, dÅí emowhtum (BRADY) f L,", ¥H. x cf. tnbZZisscztum (BRAbY) f L -Cyclamma'na indsa (STACHE) r vr .C.' pusilla BRADy 'f 70 Sliigeb JMurata

As already C. stated, iaponica'AsANo an intense volcanicity has been occurred f in the above mentioned district in the Burdigalian. This assemblage is very similar to that of the Tertonian J'ust cited, except that it has a few number of species and individuals. If this tendency proceeds in such manner, it is expeeted that this may be replaced by the Helvetian foramlniferal assemblage in Chugoku. It may be said, therefore, that this assemblage indicates the transition in the deposition from the Tortonian to the Helvetian in Chugoku. As to the volcano-stratigraphical investigation, it is said that the volcanig activity in Chugoku had been the greatest in the Helvetian and the weakest in the Tortonian. Therefore, the relationship of these foraminiferal assemblages,may be at least due [to the influence of the volcanicity. Furthermere, the sediments in the North Japan, having the Burdigalian assemblage . of the last type, include the same colder species as that in Toyama Pref. etc. along the Japan Sea. Judging from the adove meptioned . facts, it may be concluded that this assemblage indicates the abnormal colder condition due to the volcanic activity in the Burdigalian, as well as in the Tortonian or the Helvetian in this district.

PALEOGEOGRAPHICAL CONSIDERA'HION BY THE FORAMINIFERAL ASSEMBLAGES

The Chugoku massif and probably the southwestern Japan may have been a peneplain in the pre-Miocene time, except the Oligocene Ashiya transgression from Sasebo-Ashiya in dto northwestern Kyushu to Yuyawan-Izumo along the coast of the Japan Sea' in Chugoku. A remarkable unconformity 1ying between the lower Miocene Yuyawan group and the upper Oligocene Ashiya group in Yamaguchi Pref. suggests the existence of a 1and period prior to the lower Miocene transgression stated below. During this Oligocene-Miocone 1and stage, an intense volcanicity took place in the present coastal region of the Japan Sea. A warm climate flora comprising Lt' gzmkiamber formosana HAIsTcE and ComptoniphorIZum naum(mni NA'rHeRsT thrived on the land of this stage just cited¥ Namely, the climate of Chugoku was gradually ameliorated from the upper Oligocene to the lower Miocene. Simultaneously, the following lakes are supposed to have been made among the mountains of Chugoku. Namely, the Miyoshi and the Tsuyama lake and probably the Shimane, the Kimitani and the Kokubu 1ake have occurred in the recent site along the Japan Sea and the eoal bearing formations was formed. A very extensive marine transgression took place in Chugoku and probably the southwestern Japan during the Iower Miocene. This transgression became larger than that of the OIigoeene and combined with that of the Nligata-Toyama along the Japan Sea of North Japan. Further, as a result of the enlargement of the above mentioned lakes among the mountains of Chugoku, a large island sea emblacing many isles occurred in the present site of the mountains of Chugoku and probably the ""Setonaikai". It may be supposed that the last mentioned island sea finally connected the present Japan Sea with the pacific Miocene Foraminifera in Chugoku, Japan 7t. . Paleogeographical Map of Southwestern Japan Lower Burdigalian

1. Toyama 2. Kanazawa 3. 0ki Islands 4. Shimane Peninsula 5. Shimane Lake 6. Kimitani Lake 7. Kokubu Lake 8. Tsuyama Lake 9. Miyoshi Lake 10. Shodo-shima Lake 11. Kumano Lake 12. Sasebo 13. Fukue Lake Land area shaded with vertical lines.

Paleogeographical Map of Southwestern Japan Upper Burdigalian '

, oÅqJ+ . g$iEP ' ts t+ 13txllle .e- le. .ix l .3 , (IIItiSe.' as2.'2 Z-F

rv tb a n s(gZ! .

ng `2gslsÅr asP

;

!. Teyama 2. Ktinazawa E. Tottori 4. 0ki lslands 5. Shimane Peninsula 6.,Mhtsue 7; Shinzi{ Lake 8¥ Izume 9. 0da 10¥ Omdri 11. ida 12. Kokubu {'.-L..;,i IE.Masuda 14.Susa 15.Yuyawan 16.Geinichi--wan 17.Nozima 18.Takahara 19.Miyoshi 20¥Shobara 21.Tari 22.Tojo 23.Tsuyama 24.Hiroshima 25.ShinL ¥ ichi 26. 0kayama 27. Suzuka Lake 2'8. Miyai 29. Tanabe 30. 0ita Lake' Land area shsded with venicai lines. ' r

7S shigee . Murata Paleogeographical Map of Southwestern Japan Helvetian

1. Toyama 2. Kanazawa 3. Tottori 4. 0ki lslands 5. Shirnane Peninsula 6. Matsue 7. Shinzi Lake 8. Izumo 9. 0da 10. 0mori 11. Ida 12. Suzuka Lake 13.0ita Lake '. Land area shaded with venical lines.

Paledgeographical Map of Southwestern Japan ' Tortonian and Sarmatian

1. Toyama 2. Kanazawa 3. 0ki lslands 4. Tottori 5. Shimane Peninsula 6. Matsue 7. Shinzi Lake 8. Izumo City 9. 0da IV. Omori 11. Doki 12. Nagoya 13. Ayukawa 14¥ Suzuka 15. 0saka 16. Kobe 17. AwaziTsland ' 18. Shodo shima Lake 19¥ Ishizuchi Lake 20. 0ita Lake 21¥ Iki Island , 22. Yarne Lake 23. Miyazaki 24. Kushikino 2S. Tanegashima Land area shaded with vertical Iines¥ Miocene Foraminifera in Chu'goku, Japan 73

Ocean in the Burdigalian age. Such connection in the Burdigalian age gave rise to the two foraminiferal assemblages along the Japan Sea coast, namely the warmer type in the vicinity of Kokubu district, and the colder type around the Shimane Peninsula indieating,the abnormal condition due to the volcanicity and others. During the Burdigalian-Helvetian age, a 1and emergence occurred in Chugoku, except the present coastal region of the Japan Sea, and the pre-Helvetian sediments mentioned above were subaerially denudated. The Helvetian indicates the most abnormal colder condition, because the volcanism of this age was most violent in the Miocene of Chugoku. The volcanism mentioned above was gradually weakened in the upper Miocene. Accordingly, the more normal foraminiferal assemblage, affected by the colder condition, was formed in the Tortonian age. During the above mentioned events in the Miocene, a rapid subsidence of the sea bottom took place around the so-called C"Shinzi,,geosyncline". This geosyncline attained its maximum development in the Tortonian, and existed until the Sarmatian, the uppermost Miocene, when this was filled up with some shallow water sediments. In the uppermost Miocene, the sea became shallower and the Matsue sandstone formation, which contains abundant frustules o'f diatoms etc., was deposited in this geosyncline. This evidence suggests that this sediment may have been deposited under the colder condition. Although the climate of Chugoku was warmer in the lower and middle Miocene than at present, it was deteriorated gradually toward the upper Miocene.

CONCLUSION , As a result of the stratigraphical, micropaleontological and paleo-ecologieal i'nvestigation of the foraminifera in Chugoku, follewing facts are recognized: (1) The Miocene fossil remains of the smaller foraminifera in Chugoku were found in three stages, namely the Tortonian, the Helvetian and the Burdigalian. (2) These assemblages are divided into two types, namely the wamer type'deposited in an open and an island sea, and the colder type including three transitional abnormal conditions due to the volcanicity and others. (3) During the Burdigalian, the greatest transgression in the Miecene of Chllgoku occurred and a large island sea having many isles was formed in the present site of the mountains ef Chugoku and probably of the ""Setonaikai", and the connection of the Japan Sea with the Pacific Ocean took place through the island sea.

DESCRIPTIO.N OF NEW SPECIES

Vagi'raulina chugokuensis MuRATA, sp¥ nov¥ Plate. 1. Figs. 3a, b. Test very elongate, several times Ionger than broad, side subparal}el, gradu?Ily increasing in width toward apertural end; chambers numerous, the first few coiled, as mueh as 12 chambers in uncoiled ponion, dorsal gide htgher than ventral; sutures distinct, oblique, 74 . Shigee M¥urata limbate, raised; aperture radiate. Length up to 2 mm. Holotptpe.-Loc. no. MM-101, Yoshino, Katsuta-gun, Okayama Pref. (Lat. 35" 2' 50'i.4 N.i Long. 1340 9' 36'i.5 E.).Katsuta group, Miocene. ' Remarks-This new species resembles Vuginzslina mizeraensis AsA"To with the exception of the curved test. This is also cloq.ely allied to Z;dizrgv'nuZina silicLela (PLuMMER) CusHMAN, the upper Cretaceous Arkadelphia Marl¥of Arkansas, with the exception of the eharacter of the sutuTe.

REFERENCES AsANo, K. (1951) Recent and Tertiary CorcZamma'na from Japan and the Adjacent Regions. . Short Papas, Inst. GeoZ. Paleont. Tohohu U,u'v., 3, 13-24. (1953) Miocene For¥aminifera from tbe Shintotsugawa Area, Kabato¥gun, Hok- kaido. Trans. Prec. Paleont. Soc. Japan, Ar.S., 10, 45-54. IKEBE, N. (1949) Tertiary Stratigraphy of Western Toyama and Eastern Ishikawa Pref. Sct'ence of the Ettrth, 1, 14-26. (1948) On Letter Nomination. Joar. Assoclat. Geol. Collabor. 2, 1-12. IMAM¥ URA, G. (1951) Tertiary of western t"San-in", Japan. .17our, Ceol., 57, 307. IMAMURA, G., HAsE, & WADA. (1951) Paleogene of Eastern Yuyawan, Otsu-gun, Yama- guchi Pref. Jour. (]eol. 57, 306. IMAMURA, G. & TAi. (1950) Outline of Tertiary in Northern Hiroshima PreÅí Jotzr. Gbol. 56, 299-300. IMAMURA, G, TAr, URA'rA & MuKAT. (1953) Neogene of the Vicinity of Matsue City, 'Shimane Pref. Joztr, Geol., 59, 358. KANEHARA, K. (1936) Geology of Northern Geinichi-gun, Keisho-Hokudo, Korea. Jozer. Ceol., 43, 73-103. MATsusuiTA, H. (1949) Geology of the Coal-Fields in Northern Kyushu. Jour. Mint'ng Inst. Korushu, Speciat Papa. ' MiYOSHI, T., YAyosHI. (1951) On the Tertiary of Miyoshi Basin, Hiroshima PreÅí Minercsg. Geology., 4, 90-93. MURA'rA, S. (1951) Miocene CorcZammina in the Vicinity of Matsue City, Shimane Pref. Jour. Ceol., 57, 509-510. (1951) On the Paleo-ecological Investigation of the Fossil Foraminiferal Fauna in the Miyazaki Group. ¥ Bull. Korushu Inst. Techmol. 1. 91-104. (1952) The Smaller foraminifera from the Miocene deposits of the Miyoshi and Tsuyama Basin, Chugoku, Jour. Ceol., 58, 491-492. NAGAHAMA, H. (1953) On the Geological Age of the so-called Sasebo Group. Jour. Geol., 59, 401. NAGAi, K. (1951) Tertiary Stratigraphy of Ishizuchi-yama, Shikoku, Japan. Jour. Geol., 57, 291., ¥ OTUKA, Y. (l937) Geologic¥al Age of Hamada Tertiary. Jour. G'eol., 44, 161-167. Miocene Foraminifera in Chugoku, Japan 75 ¥

SAITo, R. (1953) Correlation of the Paleogene in Kyushu and Hokkaido. Hokkaiao. GeoZ. Surv. Rep., 23, 1-14. Suso, K. (l951) Neogene of the Eastern Tsuyama Basin, Okayama Pref. Jour. Ceol., 57, 291. TAi, Y. (l952) Stratigraphy and Geological Structure of the Cent]ral Area of Shimane Peninsula, Shimane Pref. Jour. Geol., 58, 573-583. TANAi, T., KATTo & TANi, (1950) Geolegical Structure of Kumano Coal-Field. Jour. Ceol., 56, 283. ToMITA, T. & SAKAI, E. (1939)Cenozoic Geology of the Fujina-Kimachi District, Izumo Province, Japan. Jour. Shanghai &i. Inst., 2, 147.

EXPLANATION OF PLATE l Figs. Ia,b. Cptclarnmina J'aponica AsANo Å~44 Figs. 2a,b. Cyclainnzina pusiZla BRADy , Å~80 ' Figs. 3a,b. PTaginuliua chugokwnsis MuRA'rA n. sp. Å~80 Figs. 4 Margr'nuZina senclaiensis . AsANo Å~80 Figs. 5a,b,c. Eponides praecinctus (KARRER) Å~80 Figs. 6a,b,c. Rotalt'a inLfZata (SF"GUBNZA) Å~80 .

/ Bull. Kyushu lnst. Technol. No.4 Platel

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