ISSN 0031-0204

Transactions and Proceedingsof thePalaeontological Society of Japan
New SeriesNo. 109

Palaeontological Society of Japan
April 30, 1978

Itaru HAYAMI

Editor

Associate editors Tsunemasa SAITO and Tomowo OZAWA

Officers for 1977 - 1978
Honorary President:
President:

Teiichi KOBAYASHI

Ryuzo TORIY AMA

Councillors:

Kazuo ASAMA, Kiyotaka CHINZEI, Takashi HAMADA, Tetsuro HANAI,

Itaru HAY AMI, Syozo HAY ASAKA, Hisayoshi IGO, Tadao KAMEl, Kametoshi
KANMERA, Tamio KOTAKA, Tatsuro MATSUMOTO, Tsugio SHUTO, Yokichi
TAKA YANAGI, Toshimasa TAN AI, Hiroshi UJIIE
Members of Standing Committee:

Kazuo ASAMA (Finance), Kiyotaka CHINZEI(General Affairs), Takashi HAMADA (Foreign Affairs), Tetsuro HANAI, Itaru HAYAMI (Transactions), Hisayoshi IGO (Planning), Kametoshi KANMERA(Special

Papers),

Ikuwo

OBATA

(Membership),

Yokichi

TAKAYANAGI("Fossils"), Hiroshi UJIIE, Juichi YANAGIDA
Secretaries:

Ienori FUJIYAMA (Special Papers), Kunihiro ISHIZAKI ("Fossils"),

Tsunemasa SAITO

and Tomowo OZAWA (Transactions),

Hiromichi

HIRANO and Yasumitsu KANIE (Membership), Toshiyuki YAMAGUCHI(General Affairs)
Auditor:

Tatsuaki KIMURA

The fossil on the cover:Original figure of Podozamites Reinii GEYLER,

1877, from the Tetori group. GEYLER'S description marked the onset ofmodern palaeontology in Japan.

All communications relating to this Journal should be addressed to the
PALAEONTOLOGICAL SOCIETY OF JAPAN,
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University of Tokyo Press, Hongo 7-3-1, Tokyo, Japan.

Trans. Proc. Palaeont. Soc. Japan, N. S., No. 109, pp. 223-2:'4, pis. 31, 32, April 30, 1978

684. DISCOACTINOCERAS AND THE DISCOACTINOCERATIDAE,
FAM. NOV.*TEIICHI KOBAYASHIJapan Academy, Tokyo

Abstract. Discoactinoceras used to be placed in either the Huroniidae or the
Polydesmiidae is quite distinct from them in the growth of intrasiphuncular stereoplasmic deposits from the actinoceroid to endoceroid type. Because its septal neckis of Armenoceras type, it must be a derivative from the common stock with the
Armenoceratidae. In longitudinal section the septum looks sigmoidal by an adoral
and adapical bent respectively near the conch and septal neck. From these distinctions a new family, Discoactinoceratidae, is proposed for the genus. Here, not only
Discoactinoceras multiplexum, the type-species of this genus, but also D. cf. multiplexum and D. okdongense, nov. from South Korea are described in detail.

Discoactinoceras known from South
Manchuria and North Korea is an interesting genus having shoulderedn nummuli
like the Huroniidae, but its siphuncular
structure is very complicated. Because
the description of its type-species andgeneric diagnosis written almost fifty
years ago is inadequate, they are here
redescribed. Discoactinoceras multiplexum
was monotypic. Five specimens containedin SHIRAKI collection from South Korea
represent two forms of this genus forone of which a new name is proposed.
Discoactinoceras has been placed in the
Huroniidae or the Polydesmiidae, buteither one of them is unable to have it
in its domain principally because of thepossession of double structural elementsof the siphuncle. The family Georginidae
recently proposed by WADE; from Australia also have double elements in its
siphuncle, but these elements are essentially different from those of Discoactino-

ceras. Therefore a new family, Discoactinoceratidae, is here established.
Judging from the siphuncular structure
this family indicates an aberrant branchissued from the common stock with the
Armenoceratidae in the middle Toufangian or middle Mohawkian age by parallel specialization to the Endoceratida by
the benthonic adaptation in the grownstage.

Family Discoactinoceratidae, fam. nov.
Diagnosis:-Actinoceroid with a large
marginal siphuncle whose deposits consistof outer annuli and inner tubular or conical sheathes; septa geniculated in proximal and distal parts; septal neck armenoceroid.
Remarks: - Since FOERSTE and TEICHERT'S reference (1930) Discoactinoceras
has long been allocated in the Huroniidae,
but as detailed below, it is sufficiently
distinguishable from that family. This
genus must have been evolved from an* Received June 16, 1977; read Oct. 16, 1977
at Kumamoto.

223

224

Teiichi KOBAYASHI

unknown common stock with the Armenoceratidae, but the high specialization requires its isolation from that family,
Judging from its complexity of the septa
and siphuncle it is quite improbable that
it is ancestral to the late OrdovicianSilurian Huroniidae.
Its siphunucular
structure is incomparable with the radially disposed longitudinal lamellae orendosiphuncular blades by TEICHERT and
CRICK (1974) in Huroniella servenense(FOERSTE and SA V AGE, 1927).
This genus was once located in the
Polydesmiidae by CHAO et al. (1965), but
as I have alreadY detailed that family in1940 and 1977, Discoactinoceras has inner
tubular sheathes on one side and its annuli do not grow in horn-shape as in thatfamily on th e other.
In the Georginidae tubular deposits
called endocones by VI' ADE (1977) sometimes appear in the central cavity ofGeorgina and well developed in the cavityof iv!esaktoceras like in Discoactinoceras.
In the radially lamellate structure of thenummulus and particularly in the so-called
engraft by VI' ADE, however, that family
is quite distinctive.
Thus. Discoactinoceras is isolated fromthe Huroniidae, Polydesmiidae, Georginidae, or else in the Actino ceratida inits double structure in the inner andouter parts of the siphuncle so farthat a new family should be instituted
for it.
Distribution :-Middle Ordovician; Eastern Asia.
Genus Discoactinoceras KOBA YASH!, 1929

Diagnosis: - Orthoconic actinoceroid
with large marginal siphuncIe; septa
geniculated near siphuncle and shell wall;
septal neck armenoceroid ; siphuncular segment very wide, shouldered near septal
neck; siphuncular deposits beginning withannuli, but becoming later tubular orconical sheathes; central cavity broad
primarily, but later narrowing and becoming tubular; radial canals branching
off from central cavity or tube and extending laterally through sheathes; stereoplasmic deposits undeveloped in camerae.
Surface of conch. apical end and bodychamber unknown.

Type-species: - Discoactinoceras 71lultiplexu11l KOBAYASHI, 1929.
Remarks:-In the large siphuncle withshouldered nummuli and septal geniculation this genus resembles Huroniella. It,
however, differs essentially from Hllronia
and Huroniella in the marginal positionof the siphuncle in this genus. The
siphuncular deposits are unusually complicated in this family. The genus wasallocated in the Polydesmiidae (CHAO etaI., 1965), but the siphunclar structure ofthat family is quite different from thatof this family.
The septa of this genus is more or
less' sigmoidal, although its middle mainpart is nearly straight. The sigmoidal
septa may be comparable to those of
Gonioceras, but it is no more than a parallelism in the trend of specialization.
because Gonioceras is quite different inmost other characteristics.
Recently CHEN and LIU (1976) described
two new species of Discoactinoceras,
platyventrum and wuyangshanense, fromthe middle part of their Machiakou suitein Shantung. The latter species appears
to resemble D. okdongense, while theformer is quite distinct from Discoactinoceras in the Actinoceras-type septal
neck and especially in the structure in
the inner part of the siphuncle.
Distribution:-Toufangian and its correlatives in Korea, North China andSouthern Northeast China.
Recently CHEN and LIU (1976) distinguished the Discoactinoceras- Loplwspira

684.

Discoactinoceras and the Discoactinoceratidae

yentaiensis zone in the middle part oftheir Machiakou suite in North China
and Northeast China and considered
Llanvirnian. Because their Machiakou
suite easily confuses the traditional Machiakou limestone, a few words are added
here.
Ordovician rocks in North China werefirst classified in about 1921 into theYehli formation, Liangchiashan limestone
and Machiakou limestone in ascendingorder, and the Machaikou fauna wascorrelated with the Black River or Mohawkian of North American by GRABAU(1922). This tripartition has long beenin current use in China. but the Machiakou limestone was subdivided into twoparts. The lower and upper Machiakou
limestone were correlated respectively to
Suite
Patou
Kechuang225

the Dawan formation and the Neichiashanseries of Central and South China where
the .series was subdivided into the Kuniutan limestone, Miaopa shale and Pagoda
limestone in ascending order (CHANG,
1964). According to Lu (1975) the Dawan
formation is Llanvirnian plus the Azygograptus suecicus zone and the .Neichiashanseries
Llandeilian-middle
Caradocian(Sinoceras sinense zone) in age.
According to CHEN (1976) the postLiangchiashan rocks of North China,
namely the traditional Machiakou limestone, is classifiable into four suites, restricting the Machiakou suite to a partof the limestone and they are correlated
to the North American sequence as below.

North American correlative

Cephalopod zone

Gonioceras badonellse
Mohawkian

None

Machiakou

Tofangoceras pauciannulatum
Stereoplasmoceras pseudoseptum

ChazyanPeianchuang

Ordosoceras quasililleatum
Polydesmia zuezshanensis

Whiterock

Subsequently, however, the Discoactinoceras-Lophospira yentaiensis zone wasadded at the middle part of the Machiakou suite (Lu et aI., 1976). Then, whatbears Lophospira yentaiensis on the zonation is a question. Lophospira yentaiensis
ENDO is a member of the Kangyao fauna
which ENDO (1932) correlated to the early
Chazyan or Mosheim fauna of eastern
North America. The Mosheim limestone.
Alabama is lower Chazyan, but the Stones
River group in Tennessee and Kentucky
is Black River in age (TWENHOFEL et al..
1954). Therefore, neither Lophospira yentaiensis nor abundant Lophospira suggests
merely Chazyan for the Kangyao correla-tive. Incidentally, lower Chazy an orWhiterock of today is approximate to
Llanvirnian. while Black River is early
Caradocian or thereabout in the British
sequence.
ENDO (1953) rectified the position of the
Kangyao formation as the subjacent unit
to the Ssuyen formation, eliminating the
Wuting formation from the intercalation
between the two other formations andallocating it beneath the Kangyao. Thismeans that the yentaiensis horizon ishigher than thought before. Likewise. itis probable for the Machiakou suite toextend up into the early Mohawkian orBlackriverian in view of the fact on the

Teiichi KOBAYASHI

226

hiatus of any fossil in Kechuang suite.
According to CHEN (1976) Discoactinoceras occurs in the lower and middle
parts of the Machiakou suite but not in
the upper part \vhich contains, however,Armenoceras manchurense, an associatewith Discoactinoceras mliltiplexum III
North Korea.
As the result of the above discussion
it is concluded that Discoactinoceras as agenus ranges through the lVlachiakou
suite whose range is post-Whiterock but
probably pre-Trentonian.

Discoactinoceras 11l11ltiplexum
KOBA Y ASH!, 1929
Plate 31, Figures 1-5, Text-figvx.os 1-2
1929. Discoactinoceras mulliplexum KOBAY ASHI, Japan. Jour. Geol. Geogr., Vol, 5,

no. 4, p. 202, pI. 22, figs. a-d.
1931. Discoactinoceras mullipl eXU11l KOI3A YA·SHI, Bull. Geol. Surv. Chosen ([(orea) ,Vol. 11. no. 1, p. 56, pI. 4, figs. la-b.

Description: - Conch large. straight,very slowly tapering, subcircl!lar in crossText.figure 1. Pharagmocone of
Discoactinoceras multiplexum.

section. Siphuncle almost circular incross section, nearly as large as a halfof conch's diameter, located marginallyor ventrally, distinctly nummuloidal withbroad central cavity but becoming narrow, longiconic or tubular where it issurrounded by sheathes.
Siphuncularsegment distinctly shouldered, but notannulated at the top as often seen inhuronioids.
In longitudinal section septa more orless sigmoidal, suddenly bent forward
near shell wall and then ad nate withshell on distal side, but on the other side
they are abruptly bent in- and backward,
then sharply recumbent and inserted between nummuli; main part of septum
between these two bents long, nearlystraight or very slightly convex backward. Connecting ring strongly convex
on adoral side and broadly rounded on
the other side. Annuli in early stage
composed of some concentric layers, but
becoming roundly quadrate and separated
from neighbouring neck rings by radial
canals; subsequent layers less convex
and connected with neighbouring ones;
at length they become conical or tubular
sheathes where, however, they are penetrated by radial canals at places.
Endosiphuncle long, conical in adoralpart, but narrow and tubular on the otherside. Radial canals extending from itlaterally with weak convexity on adapicalside and terminating near median partof connecting ring. Septal suture apparently ascending ventrally. Camerae freefrom stereoplasmic deposit. Surface ofconch, apical end and body chamber unknown.
Observation :-In cross section of theholotype specimen it is seen that thesiphuncle is in direct contact with theouter shell. judging from the sinuate
septal sutures on the siphuncle exposedon the limestone slab, the sutures are684.

Discoactinoceras and the Discoactinoceratidae

ascending toward the venter.
In the longitudinal section of the specimen the boundary sheath between theouter semicircular and inner tubular layers
is particularly well defined. The more
inner sheathes are recrystallized, butradial canals penetrate the recrystallizedpart at some places. In cross section of
the siphuncle the boundary sheath is circular but the circle takes zigzag course
and radial canals penetrate projections.
In the Cho'san specimen the boundary
sheath is clearly defined in the whole
length of the siphuncle, but the more inner sheathes are ill-preserved.
Because the septa are thin and thecamerae free from stereoplasmic deposits,
the camerate part was largely destroyed
and the siphuncle exposed. As the result
the outer surface of the nummulus waseroded in these specimens in different
degrees.
Comparison :-Without seeing the typespecimen of this species SHIMIZU and
OBA TA (1935) expressed their opinion
that this species is identical with Armenoceras submarginale (GRABAU) in pI.
VIII, figs. 5a-b, pI. XI, fig. 3, GRABAU,
1922, but the two species are quite different in all essential characteristics ofmarginal siphuncular position, septal geniculation, shouldered nummuli and themost complicate siphuncular structure ofthis species.
Occurrence: - The holotype specimen
was collected by K. MITSUISHI from darkgray banded limestone near Chiushukou
in the Niuhsintai basin, Liaoning, Northeast China in association with Ormoceras(Paraarmenoceras ?) tani (GRABAU) andOrmoceras (?) submarginale (KOBAYASHI).
The second specimen was procured by
Chong-weon KIM from gray spotted
limestone at the northern cliff of Clailgpyong-dong, Nam-myeon, Ch'osan, P'yeongan-bukto, North Korea together with227

Armenoceras manchurense (KOBAYASHI),
Onnoceras (Paraarmenoceras ?) tani (GRABAU), Ormoceras nanum (GRABAU) andStereoplasmoceras? submarginale (KOBAYASHI).
Judging from the cephalopod
association the multiplexum horizons at
the two localities are considered coeval
with each other. They are certainly
within the Toufangkou limestone.
In the vicinities of P'yongyang, North
Korea the Toufangian series consists offour units of strata in descending order
as follows:

4. Nanso or Namjang formation, barrenof fossils.
3. Unkaku or Unhak formation containing a copious fauna including Labechia,
Lophospira, Ormoceras and Armenoceras, etc.
2. Bantatsusan or Mandalsan formation
containing Stereoplasmoceras and 01'moceras rarely.
1. Maruyama or Hwansan formation
yielding Polydesmia and cameroceroid.
On the basis of the present knowledge
the Toufangian series in North Korea,
South Manchuria and North China is tentatively correlated as shown in Table 1.
As discussed already (KOBAYASHI, 1977),
the Maruyama, Leichuang and Peianchuang faunas all characterized by Polydesmia are approximately coeval with
the Whiterock of North America. The
Wuting fauna exclusive of Canadian fossils would be about the same age, although neither Polydesmia nor Ordosoceras
is contained in it.
The Machiakou limestone was primarily
named for the post-Liangchiashan limestone, although the superposition of theMachiakou on the Lianchiashan limestone
was actually indeterminable, because theformer in the Kaiping basin and the latter in the Liukiang coal-field were separate exposures in eastern Hopei (formerly

Teiichi KOBAYASHI

228

Table 1.
I

North Korea
KOBAYASHI,
1966b
Nanso

North China

South Manchuriai

I KOBAYASHI, I ENDO,
I
1966ai TapuUnkakuI

1953

Maruyama

I UnnamedI

CHEN, 1976
Patou

Tangshanupper

Lincheng

middleI

Wushanlower

I Wuting

Leichuang

Peianchuang

I Toufangkou , Kangyao
BantatsusanI

Hsiaofankechuang

I Ssuyen

I

I

OBATA, 1965!

Chihli). The Machiakou fauna describedby GRABAU, however, can safely be correlated to the Toufangkou and Unkaku
faunas. Fossils are, however, uncommon
in the Bantatsusan formation and apparently absent in the Nanso formation.
Similarly, the Tapu formation is almost
barren of fossils, although Stereoplasmoceras was later reported from the Hsiaofankechuang stage and Gonioceras described from the Patou suite recently.
ENDO proposed the Ssuyen formation
for the Armenoceras rich upper part andthe Kangyao for the Lophospira richlower part. Armenoceras, Lophospira andother Middle Ordovician fossils are foundcoexistent in the Toufangkou and Machiakou limestones.
OBA TA distinguishedthree stages in this fossiliferous limestone
and Chen also made its tripartition.
Armenoceras, Stereoplasmoceras and Tojangoceras are common and persistent
genera all through these stages or parts.
Armenoceras coulingi and A. 1'esseri, forexample, belong to the lower division by
CHEN but to the Lincheng stage by OBATA. Thus the reference of these species
disagrees between them.
Ornzoceras tani is referred to the lower
Machiakou fauna as well as the Wushan
fauna in association with Discoactinoceras
multiplexum in the former. Therefore themultiplexum horizon may be located in

Machiakou

the lower part of the Machiakou suite.
Ormoceras nudum and Armenoceras mal1churense, on the contrary, are considereda Tangshan member by OBATA and alate Machiakou member by CHEN respectively. Although it requires a further
investigation to solve the question, it isalso probable that the horizon in question lies in the lower Unkaku or the
Lincheng stage, if considered the rarityof fossils in the Bantatsusan formationand its equivalents in Koreo-Manchuria.

Discoactinoceras cf. multiplex1I11l
KOBA YASHI, 1929
Plate 32, Figures 1, 2

Tanggok specimen 9 cm long was cut
into three pieces to see its cross section.
In the middle 62.5 mm 5 nummuli arecountable in longitudinal section in thelength of 23 to 24 mm. The siphuncle isthere 19 to 21 mm broad at nummulus
and 16 to 18 mm broad at septal necks.
The septal geniculation and recumbenceat the neck are seen clearly near theconstriction. The nummulus is distinctly
protruded antero-Iaterally. In the adoralpart annuli are only partly lined back bytubular sheathes, while tubular and longconical sheathes are developed on theother part. In the middle part it is seen

684.

Discoactinoceras and the Discoactinoceratidae

that radial canals are closed by a few
sheathes. The apical angle of the endosiphocone or conical central cavity is
about 10 degrees. The central cavity ishalf as wide as the siphuncle where it is
wide open on the adoral side. In crosssection the annulus is penetrated byradial canals at a place on the adoralside. In the section of the adapical partsheathes are irregular in outline, but thecentral part appears more or less crescentic rather than circular or elliptical.
On the eroded surface of this specimen
some septa are seen to be extended fromthe siphuncle laterally and adorally.
Hwangjiri specimen is an adoral partof a phragmocone, 3.5 cm in length and2 cm in diameter of siphuncle; nummuli
0.5 cm on an average. In longitudinal
section septa are seen near the siphuncle
on its two sides. They are distinctly
geniculated just before insertion between
constrIctIOns. Short septal brim adnateswith septa. Not only the outer side but
also the inner side of the annuli are somewhat dissolved before fossilization, insofar as can be judged from their irregular outline. Nevertheless it is certainthat the central cavity of the siphuncle
is broader than a half of the siphuncular
diameter. No trace of tubular sheathes
is seen on this specimen, for this is theadoral part of the phragmocone.
This form agrees fairly well with Discoactinoceras multiplexum, but the lessdeveloped sheathes in the broad central
cavity and lunate cross section of thecavity suggest that this is probably a
distinct species,although its denomination is postponed.
OCCllrrence: - The two specimens in
SHIRAKI collection were procured from (1)Tanggok and (2) North of Sinch'on,
Hwangji-ri, both in Sangjang-myeon,
Samcheok-gun, Kangweon-to,South Korea,
probably either from the Tsuibon lime-229

stone or limestone lenses intercalated in
the Chikunsan shale.

Discoactinoceras okdongense
KOBAYASHI, sp. nov.
Plate 32, Figures 3-5This species differs from the precedings chiefly in the subovate cross sectionof the siphuncle and relatively narrow
central cavity. It is represented by three
specimens as follows:
The largest specimen from Okdong
which is the holotype was a siphuncle 17
cm long, but it was cut into three pieces
to see cross sections. Its diameter enlarges from 10 mm at narrow end to 20
mm at the other. Ten nummuli are distributed in 40 mm in the adapical part,but in 46.5 mm in the adoral part. In
cross section the siphuncle is sub ovate
and its broad flattened venter is in contact with the shell of the conch. In longitudinal section the septum is inserted
between two shouldered nummuli andabruptly recumbent at the end. The tubular deposit is seen to line annuli. The
central cavity is no more than one-third
the siphuncular diameter.
The recumbent septal neck is clearlyseen in the second specimen which wascontained in the same slab from Okdong
with the preceding. Annuli are not yet
lined by tubular sheathes. The central
cavity is narrower than a half of thesiphuncular diameter at the adapical end,
but it is expanded more than a half ofthe diameter at the other end.
The third specimen from Hyeoleom isa phragmocone 55 mm long; 5 camerae
found in the length of 20.5 mm. Its crosssection shows that the shell is attachedto the siphuncle at the broad more orless flattened venter. The central cavity
in the section is broad and lunate withconvexity on the dorsal side. On the

230

Teiichi KOBAYASHI

left side of the longitudinal section one
can see narrow camerae near the zone ofcontact. There the septa are gently inclined for some distance, but abruptly
geniculate near septal necks. Annuli are
well developed, but no tubular lining is
as yet deposited in this siphuncle; central
cavity relatively narrow. Episeptal deposits are present on the ventral side incamerae on the outer and posterior sides,
while hyposeptal deposits are confined tothe middle part of the anterior side. The
camerate portion is preserved also on theright side of the observer which is notpolished.
In Discoactinoceras wuyangense CHEN
and Lru the septal neck is of Armemoceras
type, the nummulus shouldered and annuli are lined with tubular and conicalsheathes as in this species, but in comparison with the thickness of the sheathes
the annuli are very broad. The siphuncle
is marginal but little mention is given of
its cross section.
Occurrence;- The first and second specimens were collected from Chinku-ri,
Okdong, Sangdong-myeon, Yongweol-glln,
Kangweon-to. The third specimen was
obtained from 1.5 km sOllthwest of Hyeoleom, Sangjang-myeon, Samcheok-gun,
Kangweon-to, South Korea.
Specialization of Discoactinoceras
As the result of the preceding description it is emphasized as the most salient
point that the siphuncle of Discoactinoceras is composed of a series of annuli
in the outer side, but invaginated sheathes
in the inner side which are conical likeendocones on the adoral side, but tubularon the adapical side. The endosiphuncle
in the central part is a conical cavity
which, however gradually merges backward with a narrow central tube or endosiphotube. The siphuncle in the adoralside where sheathes are absent, is essentially an actinoceroid siphuncle. On theother hand the siphuncular structure
where the sheathes are developed on the
inner side reveals an endoceroid-likesiphuncle, although the change from theendosiphocone to the endosiphotube is not
so sharp as in the Endoceratida. The
sheath-development is an example of parallel specialization to the evolution of the
Endoceratida which occurred in the Actinoceratida.
In the Endoceratida the endosiphotube
except for the short anterior terminus isclosed by diaphragms or endosiphuncularsegments in N athecoceras crassisiphonatum, A1anchuroceras wolungense andPenhsioceras? sp. (KOBA YASHI, 1935,1947). In Cameroceras d. manitobense thesuccessive lining of the anterior relic portion of the tube through growth yields
cone-in-cone structure in its endosiphotube(TEICHERT and CRICK, 1974). In Discoactinoceras multiplexum, however, theendosiphocone and endosiphotube arefilled up with the same kind of dirt.
In the Endoceratida the camerate portion was scarcely connected with theendosiphuncle where endocones were accumulated sheath after sheath, while in
the Actinoceratida any connection could
be maintained between the siphuncle andcamerae through the connecting rings.
In Discoactinoceras multiplexum and D.
d. multiplexum also it is known thatradial canals were extended from thecentral cavity and opened at the perispatium as in other actinoceroids, butsooner or later the canals and annuli
were largely lined on t:1eir inner side bytubular sheathes which were wavy at
first but became straight in longitudinal
section. Radial canals penetrated thesheathes at some places, but evidently
the control of the camerate portion became difficult for the soft animal through684.

Discoactinoceras and the Discoactinoceratidae

the growth of the sheathes.
In some endoceroids, Proterocameroceras,.Manchuroceras and Coreanoceras, for example, the endosiphuncular blades crossthe endocones at definite position. Although their nature and function are not
yet well known, they look incomparablewith the radial canals of actinoceroids.
On the other hand it is interesting to see
the lunate cross section of the central
tube in Discoactinoceras d. multiplexum
that it is very much like the crescentic
section of the endosiphotube of Manchuroceras. Both of them have marginalor submarginal siphuncles whose endosiphuncles are lunate in section with convexity on the dorsal side. Because thedevelopment fromtheactinoceroid
siphuncle to endoceroid like siphuncle
which occurred in Discoactinoceras means
the increase of the shell weight and theventral shifting of the center of gravity
and at the same time the devaluation of
the air-chamber for its life. Therefore
this specialization must have been related
to benthonic adaptation.
Because the shell growth of the Nautiloidea advances as a rule from exterior
to interior and in each element fromapical to oral, the armenoceroid septa of
Discoactinoceras shows its derivation fromthe stock of the Armenoceratidae, but inthis stage of construction of the septa
and camerae the septal geniculation andthe shouldered connecting ring show its
speciality of evolution. Until the growthstage of neck rings, however, the genus
was not far apart from many other actinoceroids. Judging from its camerae
and broad central cavity of siphuncle itis presumable that the animal was capable of swimming in this stage as someother actinoceroids. In the full grownstage, however, it became a vagile benthos
in view of the facts that the siphucle
became so heavy and at the same time231

the camerae lost their importance.
As discussed already (1977), the Maruyam an or early Toufangian age is approximately the Whiterock in North America
and the Llanvirnian in Europe when thefirst step of radiance has been advancedof the Actinoceratida and Wutinoceras,
Polydesmia and Ordosoceras were brought
to birth in Eastern Asia. Then the
Armenoceratidae and Ormoceratidae havedeveloped there probably from Wutinoceras in the middle Toufangian age when
the Toufangkou limestone was depositedin Koreo-Manchuria. Now this limestone
is divided into three parts. Therefore I
have tried to find out the appearance ofDiscoactinoceras more accurately, but it
was in vain for there is still some disagreement in the tripartitions by OBATA
and CHEN, although, CHEN (1976) suggested the early Middle Toufangian age forD. multiplexum. At any rate it is certainat present that Discoactinoceras is one of
the most specialized actinoceroids, insofar
as the siphuncular structure is concerned,
and it appeared sporadically some time
during the middle Toufangian age andsurvived by the end of the age or evena little later.
Finally, I have pointed out long ago(1929) that DiscosorllS resembles Discoactinoceras in the possession of endoconelike sheathes, but its conch is quite different as it is a curved brevicone. Since
than the order Dis:::osorida was greatly
clarified by FLOWER and TEICHERT (1957)
and it is known at present that such astructure occurs in certain genera of theWestonoceratidae and Discosoridae, but
the actinoceroid structure in the outerpart of the siphuncle is always absent inthem. Their end ocone-like sheathes developed gradually from the lining of thenummuloidal siphuncle. Therefore thisis another parallel specialization which
took place in the Discosorida intermit-T eiichi KOB AYASHI

232

tentl y during the prolonged three Palaeozoic periods, from Ordovician to Devonian.
Before closing this article I record here
my sincere thanks to Assoc. Professor Itaru
H A YAM ! of the University of Tokyo for
his warm assistance for its preparation.
References
CH A:" C, W .T. (1964) : Ordo vician System ofChina. S ci . R ep . of Slratigl·. Can/. China.
161 pp ., 1 table .
CH AO, Ch ink-ke, LI ANG , I-Isi-ho, T sou , I-Isip'in g , L EI, TS'ai-ke m and CH ANG , Jih-tung(1965) : Chinese Ce phalo pod Fossils. Eac hGroup of Fossils in Ch in a, 389 pp. 85 pI s .
CI-IEN, hi- yua n (1976) : Ad vances in the Ordov ician stratigraph y of North China wit ha brief desc ription of nautiloid fossi ls.
Acta P al . Sinica, vol. 15, no . 1, p. 55- 73,
pI. 1-3 .
- - and LI U, Ge ng -wu (1976) : North Chine se
rype nautiloids . In L u Yenhoo, CHU, Chaoling, CHI EN , Y i- yuan, ZHOU, Zhi -yi, CH EN,
Jun-yua n, LI U, Ge n-wu, Y O, ' 'Yen, CH EN,
Xu and X u , Han-kui: Ordovician biostratig rap hy and palaeogeograph y ofChin a. M em. Nani<illg 111.51. C eol. P a/aeon!.,no. 7, p. 43-'18, pIs . '1.

--

T ex t-fi g ure 2.
of siphuncJe in pI. 31, fig . 5.
a : annulus, c: ce ntral t ube , g : septa l ge nicuJation, r:
radial canal , t: tubular sheath.

Explanation of Plate 31
F igur e s 1--1. D iscoactinoceras mllltipleXll11l KOBAYAS HI. Two longitud in a l sections, weathe r ed
surface a nd trans ve r se section. A ll r e produced from Plate 22, fi g ures 7a-d , KOB AYAS HI ,1929. Nat ural Size . PM 005l.
Fig ure 5. Same species. Post erior part of long itudina l section in fi g . 1, four times m ag nifie dfrom the holotype specime n to s how septal ge nicul at ion ne ar siphnucle and growt h of annuli an d tubular s heathe s in the siphuncJe .

KOBAYASHI.'

Discoactinoceras

Plate 312

3

684. Discoactinoceras and the Discoactinocemticlae
ENDO, R. (1932): The Canadian and Ordo·
vician of Southern Manchuria. U.S. Nat.
Mus. Bull. 164, 152 pp. 40 pI. map.
- - (1953) : A summary of the columnar sec·tion in Manchuria. Proc. Seventh Pacif.
Sci. Congr., vol. 2, Auckland & Christchurch, p. 316-326.
FLOWER, R.H. and TEICHERT, C. (1957) : The
cephalopod order Discosorida. Paleont.
Contr. Univ. Kansas, Mollusca, '·01. 6, 144
pp.
FOERSTE, A.F. and TEICHERT, C. (1930) : The
actinoceroids of East-Central North America. Deniso7! Univ. BUll. Jour. Sci. Lab.,
vol. 25, p. 201-296, pI. 27-59.
GRABAU, A.W. (1922) : Ordovician fossils from
North China. Palaeontol. Sinica, ser. B,
vol. 1, fasc. 1, 127 pp, 9 pis.
KOBAY ASIII, T. (1929): Ordovician fossils
from Corea and South Manchuria. Japan.
Jour. Geo!. Geogr., vol. 5, p. 201-296, pI.
27-29.
- - (1931): Studies on the Ordovician stratigraphy and palaeontology of North Korea
with notes on the Ordovician fossils from
Shantung.
BUll. Geol. Surv. Chosen(Korea), vol. 11, no. 1, 60 pp, 9 pis.
----'- (1935) : Restudy on Manchuroceras with abrief note on the classification of endoceroids. Jour. Geol. Soc. Tokyo, vol. 42,
p. 736-753, pI. 21.
- - (19,10) : Polydesmia, an Ordovician actinoceroid of Eastern Asia. Japan. Jour. Geol.
Geogr., vol. 17, p. 27-44, pI. 3-5.
(1947) : _-\n observation on the endosiph-

233

uncular structure of an endoceroid. Japan.
Jour. Geol. Geor., vol., 20, p. 13-lS, pI. 4.
- - (1966a): The Chosen group of South
Korea. Jour. Fac. Sci. Univ. Tokyo, sec.
2, vol. 16, pt. 1, S4 pp.
- - (1966b): The Chosen group of North
Korea and Northeast China. Ibid., vol. 16,
pt. 2, p. 209-311.
- - (1977) : An occurrence of Ordosoceras inlehol, Northeast China, and a note on the
Polydesmiidae. Tmns. Proc. Pal. Soc. Japan, N.S. no. lO7, p. 125-134, pI. IS, 19.
Lv Yen-ho (1975) : Ordovician trilobite faunasof central & southwestern China. Palaeonto Sinica, n. S. B, no. 11, 463 pp. 50 pis.
OBATA, T. (1965) : Ordovician nautioloid zones
in North China. BUll. Aichi Gakugei Univ.
(Nat. Sci.), vol. 5, p. 50-56.
SI-Il~IIZU, S. and OBATA, T. (1935) : New genera of Gotlandian and Ordovician nautiloids. Jour. Shanghai Sci. Inst., sec. 2,
vol. 2, p. l-lO.
TEICHERT, C. and CRICK, R. E. (197'1): Endosiphuncular structures in Ordovician andSilurian cephalopods. Univ. Kansas, Paleonto Contr. 7l, p. 1-3, pI. 1-3.
TWENI-IOFEL, W. H.,(Chairman) et al.
Ordovician Comm. (1954): Correlation of
the Ordovician formations of North America etc. Bull. Geo!. Soc. Am., vol. 6, p.
247-29S, char. 2.
WADE, M. (1977): Georginidae, new family ofactinoceroid cephalopods, Middle, Ordovician, Australia. Mem. Queensland Mus.,vol. IS (1), p. 1-15, pI. 1-17.

Place Names
C: China,

K: Korea

Bantatsusan, Mandalsan IJ)E~LU (K),Changp'yong-dong ~J:5l'1/liJ (K),Chihli @~ (C),
Chinku-ni $Ji'~H! (K),Chiushukou :f};WiiI; (C),Ch'osan ~LiJ (K),
Dawan *~ (C),
Dongjeom-ni mJiSH! (K),
Hopei iDJ~t (C),Hwangji-ri 1ti!l!H! (K),
Hyeoleom i\iIc(K),
Kangweon-do ITi*ill (K),
Kangyao /i[ili! (C),Kechuang &Jf1: (C),Kuniutan!liilj:o~ (C),
Hsiaofankechuang 'H~~4?J1: (C),Leichuang ~:1± (C),Liangchiashan~*LiJ (C),
Liaoning ~~ (C),
Lincheng j:i&;:!8t (C),
Machiakou .~*iiI; (C),Maruyama, Hwansan:}LLiJ (K),
Miaopa M~ (C),Nam-myeon(K),
Nanso, Namjang
fff:1± (K),Neichiashan 3t*LiJ (C),Ok dong :Killll (K),Niuhsintai lj:o.c",il' (C),Patou i\1lIi (C),Peianchuang ~tltJ1: (C),Samcheok -=:~!f;:(K),Sangdong-myeon
J:JlnIii (K),
Sangjang-myeon J::N:OO (K),
Sinch'on ~f;j (K),
Ssuyen I19Ill (C),
Tanggok ~~ (K),
Tangshan Jl!fLiJ (C),
Tapu *~ (C),
Toufangkou JiJ:fHtli (C),P'yeongan-bukto 3f:tc~tifi (K),
Unkaku, Unhak ~~ (K),
Wushan :ii\:LU (C),
Wuting.lim (C),
Yehli l'i1'H! (C)mooTeiichi KOBAYASHI

234

Discoactinoceras 2:: ~ft Discoactinoceratidae - Discoactinoceras Ii. Huroniidae ~Polydesmiidae t;::.l\.;h,G;h, "(1,'f.:iJ~, {ll;:'ll!'Ij;H;::W~Ii.~jq15~"t:, l~t;::Ii.P:ljq15M2::Mfj;J:t7.>
Jt.!tkJ'i'~I::t' 7.>,~ "t: J:~r.::::ft 2:: Ii.~ < ~ '? "( 1,'7.>. -=t Q)~~MIi. Armenoceras ~ "t: Armenoceratidae 2:: IJ'i]-VlJt;iJ' G :$fir. L. "( :lief.: 2:: ~ *- G;h, 7.> iJ~, ~~fi.~ltJiiJij"t:li~j]lilB9"t:, ji!ij!liffiffl)"t:;E,t;::~;h,rJIl-?"(, ~ ~ S *;jj('i'~ L."( 1" 7.> • .:.;h,G Q)!l'ifM:.iJ'G t ~ftfi.ft!!Q)~f4 2:: ~ I), ~jq
15M<pQ) 1 ft'i'fJ:L. "(1,'7.>. i¥.jlji}J!fj1[")~*:2 v!l '/ 3 :/<Pt;::li. Discoactinoceras cf. multiplexum 2:: D. okdongense, sp. nov. c iJ~ii:J IJ, *jtm~:ftQ) Discoactinoceras multiplexum
2::~~':';h,G'i'.:..:.~WL.<E.L.k.

~

#

_

-

Explanation of Plate 32
Figures la-b. Discoactinoceras cf. multiplexum KOBAYASHI. Longitudinal and transverse sectionsof adoral part of a phragmocone. x P/2 Hwanji-ri specimen. PM 4296.
Figures 2a-c. Same species. One longitudinal and two transverse sections from 13 mm and
12 mm respectively from anterior and posterior ends of a siphuncle. xl. Tanggok specimen. PM 4297.
Figure 3. Discoactinoceras okdongense KOBAYASHI, sp. nov. Longitudinal section of siphnucle.
Natural size. Second specimen of Okdong. PM 4298.
Figures 4a-c. Same species. Two longitudinal and one transverse sections. Natural size.
Hyeoleom specimen. PM 4299.
Figures 5a-e. Same species. Two longitudinal and three transverse sections of the holotype
siphuncle. Natural size. Okdong specimen. PM 4300.
Repository:

University Museum, University of Tokyo.

KOBA YASHI:

Discoactinoceras

Plate 32

Trans. Proc. Palaeont. Soc. Japan, N. S., No. 109, pp. 235-258, pIs. 33-35, April 30, 1978

685.

PHENOTYPIC SUBSTITUTION OF GAUDRYCERAS(A CRETACEOUS AMMONITE)*
HIROMICHI HIRANO
Institute of Earth Science, School of Education,
Waseda University, Shinjuku, Tokyo 160

Abstract. The mutual relations among three nominal species, Caudryceras
denseplicatum, C. intermedium and C. tenuiliratum from Japan and Sakhalien are examined. C. denseplicatum and C. intermedium are here explained as a sexual dimorphic
pair from the facts that they coexist, they occur in the same stratigraphic range
and a constant numerical ratio of the specimens is kept for the duration in addition
to their morphogenetical resemblance. They should be degraded to C. denseplicatum
var. denseplicatu7ll and C. d. var. intermedium respectively.
Some main characters of C. tenuiliratum are common to those of var. denseplicatum and var. intermedium. The numerical ratio of the specimens of C. tenuiliratum to those of C. denseplicatum var. deseplicatum+ C. d. var. intermedium historically changes in the same pattern in Obira, Hokkaido and Naibuchi, Sakhalin.
Three possible explanations on the relations of C. tenuiliralulll with C. d. var.
denseplicatum and C. d. yar. intermediul1l are discussed and transient polymorphism
seems to be the most reasonable. Then C. tenuiliratul1l is degraded to C. denseplicatum var. tenui liratu m.

Introduction
Ammonites have been looked upon asinteresting and favourable material for
evolutionary study, but the detailed
evolutionary mode has not always been
established. The material which I deal
with is a species of Caudryceras whichflourished from the Turonian to Maastrichtian of the late Cretaceous. It includes
three nominal species, C. denseplicatu1Il(jIMBO. 1894), C. intermedium Y ABE, 1903
(emend. SHIMIZU, 1935) and C. tenuiliratum Y ABE, 1903, but I here regard
them as conspecific for the reasons which
mentioned later. In the present paper
they are called var. denseplicatll7n, var.
intennediu17l and var. tenuiliratum re* Received July 4, 1977: read June 14, 1975
at Morioka and Jan. 30, 1976 at Kawatabi.

spectively. No character was significantly
changed in each variety during the life
period of the species. They are very
similar to one another, although a few
characters are different as mentioned by
MA TSUMOTO (1941). The species occurs
fairly commonly in Sakhalien, Japan,
Madagascar and some other areas.
The purpose of this paper is firstly toclarify the mutual relations of these threevarieties and secondly to obtain an information about the adaptive strategy ofammonites which flourished in the Cretaceous.
I express my gratitude to Prof. Tatsuro
MA TSUMOTO, Dr. Itaru HAY AMI and Dr.
Kazushige TANABE for their discussion
and criticism. Prof. Terumi MUKAI, Dr.
Tsuneyuki YAMAZAKI and Dr. Osamu
YAMAGUCHI gave me instructive advice

Hit'otnichi HIRANO

236

on genetics. Prof. Anthony HALLAl\'!
kindly read the manuscript and gave
me some suggestions.
Prof. Tokio
SHlKAMA. Prof. Tetsuro HAl'iAI, Dr.
Ikuwo OBA TA, Dr. Takashi HAMADA,
Dr. Kiyotaka CHINZEI and Dr. Noriyuki
IKEY A gave many helpful suggestions.
Among the studied samples, those from
Sakhalien and part of Hokkaido wereobtained by Prof. MATSUMOTO andhave been generously loaned for thisstudy. These and several other specimens kept in the University Museum of
the University of Tokyo have been on
loan by courtesy of Prof. HANAI. This
study was financially supported partly by
the Science Research Fund of the Ministryof Education, Science and Culture (No.
074202 for 1975, No. 174269 for 1976), theMatsunaga Research Grant and Prof.
MATSUMOTO'S Grant. Miss Mutsuko
HAYASHIDA and Mrs. Yukiko HIRANO
assisted me in various ways.

I
148

I
E140

+

+

+46

+

0

o
,

100 200KmI

Material and method

Fig. 1. Map showing the fossil localities. N: Naibuchi, K: Kawakami, S: Saku,
R: Obira, A: Ashibets and Ikushumbets, Y:
Yubari and Oyubari H: Hobets, T: Tomiuchi, U: Urakawa.

The samples studied in this work wereobtained from the Naibuchi area in
Sakhalien and the Obira, Ashibets andTomiuchi (=Hetonai) areas in Hokkaido(Fig. 1). Those from the Naibuchi andObira areas are large in size and wereobtained in stratigraphic order. Therefore
they are suitable for the statisticalexamination. The samples are well preserved in hard calcareous nodules (withdiameter about 30 cm), though the bodychambers are not always complete. Herespecimens derived from one nodule areconsidered as one sample. For the geology of these areas and the locality
records including associated fossils see
MATSUMOTO (1942, 43), MATSUMOTO ed.
(1954), MATSUMOTO and OKADA (1973),
MA TSUMOTO et al. (in press), TANABE etal. (1977) and HIRANO et al. (1977).

Besides the material from the areas
mentioned above I examined some specimens obtained from the Kawakami area
in Sakhalien, the Saku. Oyubari, Ikushumbets, Hobets and Urakawa areas in Hokkaido and the Uwajima area in Shikoku
which are kept in the University Museumof the University of Tokyo and Kyushu
University, although they are not directly
quoted. For the specimens from overseas
areas I depended on the published papers.
The whorl of Gaudryceras is planispiral.
The morphology can be expressed graphically by projection of two planes whichcross perpendicularly to each other. Because the mode of coiling and the reliefof surface sculpture are often consideredas the specific criteria in Gaudryceras
and the tangential section enables us tomeasure these two characters, the tangen-68.5.

Phenotypic substittaion of Gaudrycems

tial section was employed for the studyof relative growth. The mensuration
was done under Nikon profile projector
V-16 and the suture lines were drawn
using Wild stereoscope.
Distribution of G([lUZnlCeras
So far as available literature is concerned, about thirty species of Caudryceras have been reported from various
localities of the world. The first appearance of this genus is in the Cenomanianof India (KOSSMA T, 1895; COLLIGNON,
1956) and J apan-Saghalien (MATSUMOTO,
1942), though a precise record in theformer region is not available. Concerning the latter, although the stratigraphy
is very well established, the occurrence
is not frequent.
Only three nominal species have been
confirmed from the Turonian, C. denseplica tum, C. intermedium and C. varagurense. The first and second occur inthe Lower Turonian of J apan-Sakhalien(jIMBO, 1894 ; SHIMIZU, 1935; MATSUMOTo,
1941, 43, 59b) and the third was reported
from the Turonian of India (KOSSMAT,
1895) and Angola (HOWARTH, 1965), withlittle stratigraphic information. A species
comparable with C. intermedium is known
from the Turonian of Angola (HOWARTH,
1965). In the Coniacian and Santonian
Calldryceras is widely distributed. The
extinction of Caudryceras occurred in the
Maastrichtian.
Through this specified time Caudryceras
may be. most abundant in the JapanSakhalien area. The biostratigraphicaldistribution and the mode of occurrence
have been preliminarily reported by
MATSUMOTO (e. g., 1942, 43, 59b; ed.,1954). The specific diversity of Caudryceras, however, is not high there. Thisphenomenon is interesting in view of thephylogeny of Calldryceras, and its anal-

237

ysis is the future problem with therevision of classically described species
in the world. Here I show the stratigraphic distribution and the number of
specimens in each zone of the sequencesof the Naibuchi and the Obira areas(Table 1). Var. denseplicatum and var.
intermedium appeared in the Inoceramlls
labiatus zone of the Turonian and continue
to the I. amalwsensis zone of the Santonian (Obira) and the I. japoniCZls zone of
the Santonian (Naibuchi), and their extinction occurred in the early Campanian(MATSUMOTO, 1942, 59a). On the other
hand, var. tenuiliratum appeared in theI. uwajimensis zone of the Coniacian,continuing at least to the I. japonicus
zone of the Santonian. The upper limitof this variety is early or middle Campanian (MATSUMOTO, 1959a), and thenumber of specimens seems to increase
with time.
I examined the chang'" of then umericalratio of var. intermedium to var. denseplica tum in the sequences of Naibuchi
and Obira (Fig. 2). The numerical ratiosof the specimens of these two varieties
do not show any significant differences(Table 2): the hypothesis of uniform ratio
is not rejected.
The numerical ratio of var. tenuiliratum to var. denseplicatllln+var. intermedium seems to increase gradually withtime (Fig. 3). The ratios in the twosequences, Naibuchi and Obira. are examined by chi-square test (2 X 2 contingency
table) to know whether the zone by zone
ratios equal to each other or not. The
results show that there are no significant
differences between the two sequences(Table 3) and that the patterns of thetransition of the ratios in these two areas
are equal to each other.
Furthermore, in the field these threevarieties are commonly fonnd in the same
nodule or one exposure. Although theHiromichi HIRANO

238

Table 1. Stratigraphic distribution of C. denseplicatum var. denseplicatum, var. intermedium
and var. tenuiliratum in Obira, Hokkaido and Naibuchi, Sakhalien.
Number of specimens
GeologicalageCampanian

Zone of
Inoceramus

Naibuchialb 1 c 1 die

alb 1 c 1 d 1 e

1 orientalis
76
japonicus

Santonian

01

01

0

0

01

01

01

01

01

01

01

0

Mh7

91 8
19-11i 019

36 100

Mh6p

0

16

17

41

11

n

01

4
amakusensis

0

21

1

22

19

0 -1\-8-82y11

Mh6a-/3

~I

34

Mh6a2

1

Mh6a1

01

01 401 401

3

21

01

21

41

0

Mh5

61

11

31

1

11

31

31

71

1

Mh4

teshioe:nsis

3111

311 35

11

01

01

1

Mh3

hobetsensis

91

21 491 60

01

01

11

1

Mh2

01

5

11

01

1

Mh1

I

MhO

mihoensis
Coniacianuwajimensis

88
TuronianLocalstratigraphic
division

Obira

m.y.

labiatus
94

0\

101

5\

I

._-

I

-

01

Cenomanian 1 concentricus

1
1
1
1
1
1
a: var. densepllcatum, b: var. mtermedzum, c: Immature specImens of var.
denseplicatum and/or var. intermedium, d: a+b+c, e: var. tenuiliratum.
n: naumanni, y: yokoyamai
\

Age

Zone
of
lin oceramus

Camp an.

orientalis

Ob iram.y.

Ratio

NaibuchiNumberSanton.

,am akusensi 5•

82 mihoensis

teshioensis
Turon.

•~.......--.
~""-"

labiatus

0

1.0

0

------.

•

•

5

10

~

• I

•

I

•

I

0

~

I

I

94 Cenoman. concentricus"x'XXX2to!

,
I

t

88 -

hobetsensis.....-.

Q var. ijaponicus

uwajimensis

Number~ var. d76 -Coniac.

Ratio

J
1.0

0

5

10

Fig. 2. Chronological changes of the numbers of the specimens of var. denseplicatu1ll
and var. intennedium and the numerical ratios of the latter to the former (95% confidence
interval is shown by a bar).

685.
Table 2.

Phenotypic substitution of Gaudryceras

239

Chi-square matrix with Yate's correction (2 x 2 contingency
table) on the ratio of the number of the specimens of var.
intermedium to that of var. denseplicatum, from the Upper
Cretaceous of Naibuchi (upper) and Obira (lower).
Datasame as Table 1.

Mh6
8:9

Mh6
0:1

Mh6
4:4

Mh6

Mh5
0:2

1:0

Mh4
3:1

Mh3-1
0:2

Mh6
Mh6

0.01

Mh6

0.09

0.01

Mh6

0.00

0.00

0.01

Mh5

0.27

-

0.23

0.19

Mh..!

0.20

0.05

0.04

O. 70

Mh3-1

0.27

-

0.23

0.19

Z20 . 05 ("=I) = 3.84

I

amak.
1:0

miho.

uwaj.

0:0

1:6

I

I

0.75
0.75

-

I
teshio.
1:3

Ihobets.
2:9

labia.

0:0

amak.
miho.

-

uwaj.

0.38

-

teshio.

0.05

-

O. 14

hobets.

0.36

-

O. 19

O. 19

labi.

-

-

-

-

Geologicalage
Santonian

I

Zone
Local
of
Inoceramus subdivision
Mh6A
japonicus
Mh6ClC.A
amakusensis .Mb..6.ct2
Mh6oc:1

Io biraNaibuchi.....--....

---...........
II

mihoensis

Mh5...........

uwajimensis

Mh4teshioensis

Mh3

.-.

hobetsensis

Mh2

••

labiatus

Mh 1

0ConiacianTuronian

-

I

•

•

•

I

.---........

I

•
I

I

I

•

I

. - ............ - - - - - - ....... -"1.- ----_. --_.. - ....

. - ............ - -I

0.2 0.4

0.6

0.8

to

..... -- ...

Q---0.2"--0.4---0.6---0:8 1.0

Fig. 3. Chronological change of the numerical ratio of var. tenuiliratum to the threevarieties in the number of specimens (95% confidence interval is shown by a bar or a dashedline) .

Hiromichi HIRANO

240
Table 3.

Chi-square matrix with Yate's correction (2 x 2 contingency table) on the ratioof the number of var. tenuiliratum to that of the pair of var. denseplico.tullland var. intermedium between the samples from Obira and Naibuchi. Data
same as Table 1.

~
Naibuchil Mh6,B I Mh6a-,B I Mh6a1+ a2 1 Mh6a2
Obira __________ 100: 36
11 : 1735: 2834: 19japonicus

19 : 0I 5.15

Mh6a1
1:9

Mh4
1:7

Mh5
0:4

1 15.0------~-------+--------.-------,-------

amakusensis 19: 221
mihoensis

3 : 40uWajimensis

1: 10

0.87

I

0.19

clear

distinction between var. denseand var. intermedium in theimmature stages is impossible, as will bementioned later, some of the immature
specimens which have hitherto been regarded as C. denseplicatum are assumed
to be var. intennedium and the rest are
var. denseplicatum from the examinationof the position of the nepionic constriction. Thus, var. denseplicatum and immature var. intermedium are coexistent.
Adult individuals of var. intermedium
sometimes occur exclusively and therefore
the habitat may be somewhat different
from those of the immature var. intermedium and other varieties. A fullygrown up and large specimens of var.
intermedium, however, independently forms
one nodule (the size of a fully grown up
specimen is nearly the same as that of acommon nodule) and therefore the associated fossils with the adult variety in a
nodule are rare. It is uncertain whether
this mode of occurrence depends on
physical and! or chemical or biologicalreasons. Var. tenuiliratum often coexists
with var. denseplicatum and assumed immature var. intermediulIl.

plica tum

Characteristics of var. denseplicatlllll
and var. intennediu1n
Ontogeny:

Generally, the growth of

0.52

2.30

3.06
0.27

I

I 0.27
parts of the body relative to that of the
body is in a certain functional relation.
called allometry, and is expressed asy=(3x" (where y represents the size ofa particular organ or a part of the body;(3 the relative size of the organ at its
first appearance; x that of the total bodyor a part of the body; and lX the rate of
growth of the organ y) (NOMURA, 1926;
HUXLEY, 1932). GOULD (1966) designatedthe term allometry as the differences inproportions correlated with changes inabsolute magnitude of the total organism
or of the specific parts under consideration. Ideally, the growth pattern of anammonite is isometric and the pattern is
recognized as a logarithmic spiral (THOMPSON, 1917; HUXLEY, 1932; OBATA, 1959.
60, 61, 65). The method of mesnurationis the same as that described in HIRAKO(1975).
The growth pattern of the whorl ofvar. denseplicatum is characterized by thehigh rate of the growth of radius length
to the spiral in comparatively later stages
as shown in Fig. 4 (Compare it with thatof var. tenuiliratum in Fig. 10 of thispaper and fig. 3 in HIRANO, 1975). The
suture line shows little variation and isexpressed as ELU2 U 1 Is in terms of theformula by KULLMAN and WIEDMANN(1970) (Fig. 5). The surface of shell iscovered by widely interspaced thin and685.

Phenotypic substitution of GaudTycem8

241

R
3
o

10.0

5.0

•
1.0

o e
o•

0.5

iii

R4018b N= 3

o R 2643p N=2

I 0•" 0I

Fig. ,1. Example of the growth pattern of the radius length (R) to the spiral (0).
Samples are from the teshioensis zone of Obira (R26.13p: var. denseplicatu11l; R101Sb :var. denseplicatu11l and/or var. inter11ledium).

comparatively high radial subcostae fromthe first whorl to the early half of thethird whorl. After the stage, numerous'
coarse and weakly sinuous subcostae(Tables 4, 5; See table 11 of tenuiliratumin HIRANO, 1975) appear, and branching
and insertion of these subcostae arise on
the lateral to the ventro-lateral side of
the fourth to the fifth whorl. At about
the sixth whorl the costae appear andcontinue later. They describe a sine
curve in cross section and the inters paces
become narrower with growth. The bodychamber occupies a little less than 360'in spiral angle, although the estimation
is approximate owing to the difficulty
in recognizing the peristome. The ventral
shell is composed of three layers and thedorsal shell is of two layers as the outerlayer wedges out at the umbilical seam.
This variety has a constriction like var.

tenuiliratum (HIRANO, 1975), and especiallythe first, nepionic constriction, is situatedat a constant position (Table 6).
C. denseplicatum var. intennedi1l11l was
at first described by Y ABE (190~) as avariety of C. tenuiliratum and regarded
by SHIMIZU (1935) as a distinct species.
After that it was treated by MATSUMOTO(1959b) as a subspecies of C. de71seplicatum.
As mentioned in the previous chapter,the variety under consideration is coexistent with var. denseplicatum and therefore the sub specific relation between themis unlikely.
The morphological characteristics ofvar. intermedium are the same as thoseof var. denseplicatum to the 5th or 6th
whorl and the differences between them
are not detected by the observation andthe biostatistic examination(Figs. 6. 7). The
growth ratio of the radius length to theHiromichi HIRANO

242

G

M

p

o
Fig. 5. Sutural ontogeny of var. denseplicatum. A-G: H2157, from Mh61', Naibuchi,
Sakhalien. A: 180· from the protoconch. B: 2.5 th whorl. C: 3.5th whorl. D: 4.5th whorl.
E: Just 5th whorl. G: Just before 6th whorl. H-N: H2153, from Mh61', Naibuchi. H: 3/4
whorl. I: Just before 3rd whorl. J: 3.4th whorl. K: 3.7th whorl. L: 4th whorl. M: Just
5th whorl. N: 5.5th whorl. 0: H023b, from Onnenai, Hokkaido. 5.25th whorl. P: var.
tenuiliratum, H5022, from Kawa-kami. Just 6th whorl. The horizontal bar indicates 1 mm.

spiral, however, increases after the 5th
or 6th whorl and we can distinguish them
if the specimens are larger than thegrowth stage. Further, the costae appear
at about 6th or 8th whorl, and continue
to one or more whorls, and the adultindividual becomes very large (diameter
30 cm±). The cross section of each costa
is quadrate in the early stage and is thesame as that. of var. tenuiliratulIl. About

one whorl later the costa describes asine-curve in cross section.
Geographic and chronologie variation:
The geographic variation of var. denseplica tum is very little like that of var.
tenuiliratum (HIRANO, 1975) and no significant differences are confirmed about
the measured characters among the population samples from Sakhalien and Hokkaido. As an example the growth ratio

685.
Table 1.

Phenotypic substitution of GaudTycems

Height of subcosta (mm) at the three different ontogenetic stages,
the 4th, the 4 1/2 and the 5th whorl, of var. denseplicatum and/or
var. intermedium. Samples are from Obira.

Age
N

.::

.~

.::

.8

243

amakusensis

x
SD
OR

~

[f)

the 4ththe 4 1/2

the 5th

7
0.019
0.011
0.008-0.036

7
0.041
0.028
0.013-0.096

7
0.078
0.034
0.028-0.098

Nmihoensis

.~u

.~

1

x

-

SD
OR

0.067

-

2
0.064
0.036
0.038-0.089

3
0.096
0.066
0.040-0.169

3
0.076
0.053
o. 0-12-0. 137

3
0.128
0.095
0.054-0.236

N

.;I

x

0.018
0.021
0.031-0.077

5
0.087
0.027
0.061-0.129

6
0.014
0.013
0.007-0.037

6
0.035
0.047
0.011-0.131

6
0.059
0.019
o. 037 -0. 071

7
0.010
0.009
0.003-0.029

7
0.027
0.015
0.011-0.055

7
0.090
0.037
0.055-0.166

Nunknown*

x
SD
OR

.::

0

u

N

uwajimensis

x
SD
OR

teshioensis

SD
OR
N

.::

.~

.::

0

1-0

hobetsensis
upper

;::J

E-<

x
SD
OR
N

hobetsensis
lower

x
SD
OR

* The detailed age is not determined.
N: sample size, x: mean value, SD: standard deviation,
OR: observed range.

of the radius length to the spiral of some
Santonian samples and the results of thestatistical examinations are shown (Tables
7, 8). Concerning the suture, no~ only
the basic elements but also the. detailed
parts show no geographic changes. Thisvariety is distribu ted as far as Madacascar and differences have not been detected
between the specimens from the JapanSakhalien area and Madagascar, although
they have not been quantitatively analysed.
As has been recognized previously, any

Hirornichi HIRANO

244
Table 5.

Table 6.

Number of lirae on a quarterof whorl of var. denseplicatum,counted at the umbilical shoulder, at some ontogenetic stages.
An example is shown by the
Sample N22Z from Naibuchi.

Stage

S.D.

Mean

3 3/4-4th whorl
4-4 1/4
4 1/,1-4 1/2
4 1/2-4 3/4
4 3/4-5-5 1/45
5 1/4-5 1/2
5 1/2-5 3/4

Stage

N

6. 1
4.9
2.5
1.4
2.1
1.3
4.0
0.0

20.3
23.7
21. 7
17.0
18.3
20.8
21. 3
17.0

Position of the nepionic constriction of the pair of var. denseplicatum and var. intermedium expressed by the angle between theconstriction and the protoconch
aperture. Samples from Obira.

naumanni zone
amakusensis zone
hobetsensis zone

3
3
3
2
3
4
3
2

N

7J

5
2

355°26355°15'365°06'

11

S.D.
1

29°45'
7°26'
6°17'

cation of suture, modification of surface
ornamentation and growth pattern ofwhorl, and the change of position of
nepionic constriction did not arise, and it
follows that this evolutionary mode exhibits a morphological homeostasis. An
example is shown by the growth ratio of
the radius length to the spiral (Fig. 8).
The mean values of the figured samples

particular chronological transition ofmorphology such as increase or decreaseof some quantitative characters (e. g.,
protoconch size), complication or simplifi-

40.0
mm

o
20.0

.
.
.
.:

o.

10.0

~

~

• 0.

5.0

•• 1

. it••
•• j

"*o
o

.~i

.1

.1

1.0

Q5

0.50

II

I I

I

•

I'

intermedium
appearance of rib

denseplicotum
appearance of rib

•

.. ,
•••

2

4

6

8

10

12

14 -n;

Fig. 6. Growth pattern of the whorl height to the spiral angle in var. intermedium
and var. denseplicatum. Var. intermedium: 13849, loco N332b, Mh6a, Naibuchi. Var.
denseplicatum: H2158-1, 2, 3, loco N22Z, Mh6 {3, Naibuchi.

685.

Phenotypic substitution of Gaudryceras

0.1602 0.1370 0.1236 0.1505
Here I test the randomness of thisseries by a runs test. The minimum
value is 0.1364, maximum is 0.1774 andtherefore the middle is 0.1569. Let thevalue larger than the middle value express a and smaller as b. Now the composition of the run is as follows.

amkusensis Zone86obefore 97(.

~

after

97(.

4
2
0r-~~~~-L~~--~~__~

12hobetsensis Zone

o

N

o

d

0

Fig. 7. Histogram of the growth ratioof the radius length to the spiral (in thestages before and after 9 rr) of the pair ofvar. denseplicatum and var. intermedium
from Obira.

in Fig. 8 are as follows in ascendingorder:
0.1774 0.1676 0.1639 0.1364 0.1529 0.1712
0.1715 0.1751 0.1588 0.1616 0.1564 0.1582
Table 7.

245

-lower horizon upper horizon~
Composition of run:a a a b b a a a a a b a a b b b
Run number:
3
2
5
1 2
3
Here we can get the total number of theruns, U =6, lOas and 6bs. In the tableof the runs test of randomness (one side
2.5,%') the rejection areas are less thanfour and larger than thirteen, and U isout of these areas. Thus we can conclude that the hypothesis of randomness
is not rejected.
Var. intermedium cannot be distinguished from var. denseplicatum until the
specimen shows mature characteristics.
Thereupon I studied and compared somecharacters in more details.
Sutural ontogeny: No significant difference is detected (Figs. 5, 9).
Position of the nepionic constriction:
The frequency distribution is bimodal (Table 9). Although the

Growth ratio of the radius length to the spiral angle after the 9rr stage in some
Santonian samples of the pair of var. denseplicatum and var. intennedium.

SampleNSO"
a±to,o5.vN

SO"

O.R.

Naibuchi (j)Obira (a)Obira (n)Ashibets (y)Tomiuchi (n)

3
10
3
2
2

O. 1374±0. 0083
O. 1461 ± 0.0158
O. 1505±0. 0134
O. 1693±0. 0520
o. 1533±0. 0540

0.00450.02240.00730.01710.0177

O. 1324-0. 1412
0.1054-0.1774
0.1442-0.1585
0.1572-0.1814
0.1407-0.1659

j: japonicus zone, a: amakusensis zone, n: naumanni zone, y: upper part ofyokoyamai zone. N: number of measured specimens,
mean of growth<;;ratios,a:~"=: standard error, SO": standard deviation, O.R.: observed range.

vN

Hiromichi HIRANO

246
Table 8.

Differences of the growth ratios among five Santonian samples of the pairof var. denseplicatum and var. intermedium. (Data same as Table 7).

Sample

Na(j)

Ob(a)

Ob(n)

As(y)

To(n)

Naibuchi (j)Obira (a)Obira (n)Ashibets (y)Tomiuchi (n)*1. 13310.3234
1. 1102
1. 4769
O. 7162*2.64390.3261

O. 1,181*(3.3173)
1. 3659
1. 7858

0.58730.17960.77050.1120*1. 6103
0.42340.26020.9207

O. '1598*

Right upper: results of t.test. When there is a significant difference between
the variances, Welch's method is, applied. Significant result at 5% level isindicated by. ( )., Noone is significant at 1% level.
Left lower: Coefficient of difference.

Zone
Geologicalofage
Inoceramus

Growth ratio

japonicus
Santonian,

N=3
N~3

I

•

I

•I

amakusensis
mihoensis,
Coniacian

N=4

•

I

'N=6
........-..

N=2

I

I

I

•

uwajimensis

I

•

•

teshioensis

N=4
Ni4
N=7
I
t---+--1 N=7

•

I

I

I
I

•

Turonian•I

hobetsensis

N=2

•

0.10

0.12

0.14

I

• N=3
•

I

labiatus

0.16

I

0.18

I

0.20

Fig. 8. Chronological change of the growth ratio of the radius length to the spiral (after
the:stage of 9 n:±) in the pair of var. denseplicatum and var. intermedium from Obira. The
mean value and the 95% confidence interval are shown. The black circle without a bar
indicates a sample composed of one specimen.

boundary cannot be set objectively,,in general the position of the char·actor, of var. denseplicatum is at
the later stage (e. g., Sample As1144: N=5, mean=368.95°, S. D.=
4.20°) and tfi~t of var. inten;iedium
is at the earlier stage (e. g., Sample
As-1129a: N=l, Angle=340.700).

The unfavourable preservation of
inner whorl of var. intermedium
impedes the confirmation of thisrelation (The preservation of inner
whorls of large specimens areushaily unfavourable).
Number of sub costae : No difference
is detected.

685.

Phenotypic substitution of Gaudryceras
Table 9.

Chi.square test on the frequency
distribution of the position of
Nepionic constriction of var. dellseplicatum and/or var. illterllledium. Sample is of the hobetsensis
zone in Obira.

Class

Oi

Ei

x-3s~x-2s

4
0
0
2
0
5

0.24
1. 49
3.75

N=l1

10.97

x-2s~x-s

x-s ~xx~x+s
x+s ~x+2s
x+2s~x+3s.

X2 = 163.40

Fig. 9. Sutural ontogeny of var. inter·medium. 13849, loco N332b, Mh6 a, Naibuchi.
A: 5-5.5 th whorl. B: 5.5-6 th whorl. C:
6-6.5 th whorl. The horizontal bar indicates
1mm.

Height of sub costae : No difference is
detected (Table 10).
Ratio of the height to the width ofsubcosta: No difference is detected (Table 11).
Growth ratio of the radius length tothe spiral: It is very difficult to
detect the difference in the stages
before the costae appear (Figs. 6, 7).
Shape of costa: Usually distinguishable (see Plates).
Table 10.

247

>

--

..,0. I;)
1. 49

o. 24

X20.05("=3) = 7 .8147

Size of the adult shell: Clearly distinguishable. Var. intermedilllil attains
more than 30 cm. in diameter but
var. denseplicatum does at . most
20cm.
Stratigraphic distribution: The stratigraphic distribution of var. intermedium is the same as that of var.
denseplicatum and if one increases
in the number the other also doesso.
Geographic distribution: Var. intermedium coexists with var. denseplicatum world-widely. In someareas which have been preliminarily
studied only one of them is reported.
Discussion: As described above, var.
denseplicatum and var. inter71ledilllll are
hardly distinguishable from each otherAn example of the height of subcosta (mm) at three defined stages invar. dellseplicatum and var. interllledium. Samples are of Santonian from
Ashibets. The results of t-test are non significant in al1 stages.

Stagevar. denseplicatum
As-1140 (N=2)
mean
S.D.

var. illtermedium
As-1129 (N=l)

t·test0.008

1. 288the 4th whorl

0.014

4 1(2
the 5th whorl

0.031

0.004
0.012

0.016

1. 0100.073

0.019.

0.048 .

0.078

248

Hiromichi HIRANO
Table 11.

Examination of the ratio of the height to the width of subcosta between
var. del1seplicatum and var. intermedium. Samples are of Santonian in
Ashibets. The results of t·test are non significant in all stages.

Stage
the 5th whorl
5 1/2
the 6th whorl

var. denseplicatum
As-11M (N =5)
mean
S.D.

o. 189o. 284
0.333

0.083
0.053
0.054

until they attained the adult condition.
The close morphological resemblance andthe fact that they coexist geographicallyand chronologically suggest they areconspecific_ We cannot expect the relation of twin species (SIMPSON, 1961) for
this phenomenon under such conditions
mentioned above.
Homeomorphy is
known in various ammonites but even insuch a case the suture, which has close
relation to their soft parts, is commonly
distinguishable, and as has been known
by the studies of SCHINDEWOLF (e. g.,
1954) and KULLMAN and WIEDMANN (1970)the suture is a genetically very stablecharacter. The essentially similar patternof rise and fall of these two phena andthe sufficiently uniform numerical ratio
indicate the likelihood that they belong
to one and the same species.
The simultaneous occurrence of several
discontinuous phenotypes or genes in a
population, with the frequency even of
the rarest type higher than can be
maintained by recurrent mutation, is
known as polymorphism (MA YR, 1970).
Examples of polymorphism are numerous
in living species. Is this case a sexual
dimorphism or other type of dimorphism
like a balanced polymorphism?
If this is a balanced polymorphism, thecharacteristic differences between thetwo phena have possibly arisen from apair of alleles of which one gene isdominant, and either var. denseplicatum

var. intennedium
As-1129 (N = 1)

o. 163o. 272
0.403

t-test0.284
o. 194
1. 172or var. intermedium is the phenotype of
dominant homozygote plus heterozygote.
In some other cases such a dimorphism
may be controlled by a kind of chromosome aberration like inversion. The relations between phenotypic polymorphism
and chromosome aberration and theinfluence of chromosome aberration are
discussed by many geneticists (e. g.,
OSHIMA et aI., 1974; DOWDESWELL, 1970)_
The polymorphism maintained by allelicgenes which are associated with theinversion is exemplified or inferred insome living mollusks (e. g., CAIN andSHEPPARD, 1954; KOMAI and EMURA, 1955).
The mechanism of this phenotypic
polymorphism is nearly impossible toknow, and similarly the distinction between the balanced polymorphism andthe sexual dimorphism is certainly difficultin this case. The proved dimorphisms,
however, of which mode of ontogeny ishardly distinguished up to the adult andadult size shows differences, in the natural world, are usually case of sexual
dimorphism, and the difference of theadult size between male and female has
been exemplified in ammonoids (e. g.,
P ALFRAMANN, 1966, 67, 69).
Thus I consider the case of sexual
dimorphism_ Here, I note the ratio of
the two sexes 0 and ~ is 1: 1 as seenin the living Sepiidae (YAMAMOTO ed.,1973) and many other organisms, although
no evidence is yet obtained in ammonoids.

685. Phenotypic substitution of Gaudryceras
Upon examination of the numerical ratiosof the specimens of Table 1, and no
significant differences are detected fromthe hypothesis of a ratio 1: 1 (Table 12).
The large size of var. intermedillm
recalls us of the autopclyploidy but sucha phenomenon is very rare in animals.
Table 12.

249

The fact that the ratio of two forms is
kept constant in two distant areas isunfavourable for the supposition of autopolyploidy.
It is most appropriate to regard themas a sexual dimorphic pair.

Chi-square matrix with Yate's correction (2 x 2 contingency table), whichindicates the significance for the difference between the numerical ratioof Yare intennedium to yare denseplicatum and idealized ratio on thesexual dimorphism (1 :1). Upper: Naibuchi, lower: Obira.

Stage

Mh6,8

Mh6a-,B

Mh6,,2

Mh6,,1

Mh5

Mh4

Actual ratio
Result

8:9
0.029

0: 1
0.667

4:1
0.250

1:0
0.667

0:2
0.000

3: 1
0.000

Stage

I amakus.

miho.

uwajim.

teshio.

hobets.

labiatus

Actual ratio
Result

1:0
0.667

0:0

1:6
0.737

1:3
0.000

2:9
1. 2640:0

I

7. 20.05("= 1) = 3.841

Characteristics of yare tenlliliratllm

Ontogeny: The ontogenetic development of var. tenuiliratllm was explained
in detail with the Santonian samples(HIRANO, 1975). The sutural pattern of
this variety is ontogenetically same as
those of var. denseplicatum and var. intermediu11l. The growth ratio of the radius
length to the spiral is smaller in thepresent variety than in the other twovarieties in the later stages. The crosssection of the costa is quadrate like thatof var. intennedium. The adult size ofthe present variety is similar to that ofvar. denseplicatu11l. In short, as mentioned
by MATSUMOTO (1941) these three varieties are different from each other in somepoints but at the same time they havecommon or similar characters in otherpoints.
Geographic and chronologic variation:
The distribution of this variety is almost
restricted to Japan-Sakhalien, but from

California (MATSUMOTO, 1959b) and South
Africa (HOEPEN, 1921) similar ones werereported as d. tenuiliratwn or under adifferent name. Cf. tenuiliratu11l, which
is not available at my hand, is however,rather rare in California and I omit thisspecies under the assumption that thistreatment does not influence on the final
results. Thereupon I studied the geographic variation of the present variety
in the Japan-Sakhalien area but no particular trend like cline was detected throughthe range as exemplified by the Santonian
samples (HIRANO, 1975).
Then I examined for chronologicalchange of the growth pattern of the
spiral from the amakusensis zone to thejaponicus zone (Fig. 10), but detected none.
Discussion: The morphological differences of var. tenuiliratu11l from var.
denseplicatu11l and var. inter11ledium aremacroscopically and biostatistically clear
in some characters as mentioned in theprevious section. The sutural pattern ofHiromichi HIRANO

250

o

o

Sample fromamokusensis Zone...

Sample fr~mj~ponicus Zone.

o
o.

o
o

o

o
t

o

... "

•
..... '"

•

100

1.0

~

after 91&~

before 9 7t.

.

I

N=4

§;
o.v

NB 3

.2..'-

0.10

2.0

I
N=1i
- N=8
-~ -

... -[]- )

~~

-I

N~l

1'~
.0800 I
0

.1 00

.1 00

N8~1400

.1600

4.0

6.0

8.0

10.0

12.0

I

.1800

14.0 nFig. 10. Growth pattern and ratio of the radius length to the spiral of var. tenuilir.a-tum from Obira. In the square, the mean value and 95% confidence interval of thegrowth ratio is .shown.

Sample from the naumanlli zone is indicated by a broken line.

var. tenuiliratunz, however, is not distinguishable from those of var. denseplicatumand var. intermediu71l.
The rise and fall of var. tenuiliratum
are exemplified in two representative
localities, NaibuclTi and Obira (Table 1),
and both two examples show that it
began to appear in Coniacian and flourished in Santonian. Next I compare thenumerical fluctuation of the specimens ofvar. tenuiliratum with that of the pair ofvar. denseplicatu71l and var. intermedium(Fig. 3).
The chronological change of the numerical ratio of the specimens of var.
tenuiliratum to those of the pair of var.
denseplicatum and var. intermedium showsnearly the same pattern in the two localities (Table 3, Fig. 3), notwithstanding
the different chronologic patterns of thenumber of var. denseplicatum+var. inter-medium in these two localities (Table 1).
That is, these patterns clearly indicatethat var. tenuiliratum replaced the pairof var. denseplicalum and var. intennedium.
Var. tenuiliratum has been regarded asingle and independent species by mostauthors. Did it speciate from anotherspecies than C. denseplicatu71i (=C; d.
var. denseplicatum+C. d. var. intermedium)or from C. denseplicatu71l in other area
like the model of allopatric speciation,
migrating to Japan-Sakhalien and flourishing there, taking the niche of C. denseplica tum ? The numerical ratios of thespecimens of three varieties (var. tenuiliratum: var. denseplicatum+var. intermedium) in these two localities are almost
equal to each other except in the case of thejaponicus zone vs. Mh6a-j3. Why did theratios change in the same pattern in thetwo places, the distance 'of which is as685.

Phenotypic substitution of Gaudrycems

great as 300 km ?
Here I consider three hypothesis which
may explain the relation between "tenuiliratum" and the pair of var. denseplicatumand var. intermedium. The first andsecond hypotheses assume "tenuiliratum"
as an independent species from C. denseplica tum. That is, 1. "C. tenuiliratum"speciated from a species other than C.
denseplicatum, migrating to Japan-Sakhalien area and adapted to an environmentof this area, 2. "G. tenuiliratum" speciatedfrom C. denseplicatum in some marginalor semi-isolated places and migrated tothe main distributional area of C. denseplica tum (as in the model of ELDREDGE
and GOULD, 1972). In the third hypothesis,on the contrary, "tenuiliratum" is thepolymorphic pair (transient polymorphism)
with the couple of var. denseplicatum andvar. intermedium. Which would be themost reasonable explanation?
Firstly case 1 is considered. The first
appearance of "tenuiliratum" is in theearly Coniacian and therefore we mustseek the ancestor in the Turonian speciesof Caudryceras. The only applicable species is C. varagurense which is known in
the Turonian of India and South Africa.
There is not more positive evidence ofthe speciation of "tenuiliratum" from C.
varagurense than the interpretations mentioned below although C. varagurense
resembles "tenuiliratum" in appearance.
In case 2 we assume that the speciationof "tenuiliratum" from C. denseplicatum
proceeded in the marginal isolated areaof the distribution of C. denseplicatumand "tenuiliratum" migrated to the mainarea, J apan-Sakhalien. after the complete
reproductive isolation was established.
According to the model of ELDREDGE
and GOULD (1972). this process is likely
to have proceeded fairly rapidly. Because
the distribution of C. denseplicatum of
Turonian age is only J apan-Sakhalien, the251isolated population must have arisen in
the marginal part of J apan-Sakhalien. The
Turonian sediments occur in great thickness and lateral extent in this area, andfossil preservation is very good. However,
we have not succeeded in finding theintermediate form of those two "species"
under discussion for the last 100 years
from any locality. If we supposed that"originally such an intermediate form
existed", here we can apply the modelof ELDREDGE and GOULD (1972) (I do notintend to deny their model). If thetransformation of morphology from thecouple of var. denseplicatum and var.
intermedium to var. tenuiliratum is gradual, the discovery of intermediate individuals would be expected. On the other
hand if "tenuiliratum" arose as a resultof adaptation for different conditions thandenseplicatum, the optimum condition of
the former would have been much different from that of the latter. However,the fact that these two "species" coexisted for 12 million years after the"speciation" denies this necessary condition.
Thereupon I search for a more reasonable explanation. That is, we are led tothe thought that "tenuiliratum" is one
and the same species as denseplicatum.
Although they are one species, the heightof the subcostae and the whorl growth
pattem in some stages are different andthere is no intermediate form. Therefore,
they should be regarded as a pair ofdimorphism. In spite of the different
durations and the different patterns oflocal rise and fall in Japan and Sakhalien,
the relative frequencies of "tenuiliratum"to the pair of var. denseplicatum and var.
intermedium are in the same pattern asmentioned in the early part (Table 3, Fig.
3). This fact seems to suggest transientpolymorphism. That is, var. tenuiliratum
may constitute dimorphism with the pair252

Hiromichi HIRANO

of var. denseplicatum and var. intermedium, and arised by some mutation (genemutation, chromosome aberration, position
effect of supergene or other case) fromthe pair of var. denseplicatum and var.
intermedium earlier than the early Coniacian, and survived until the middle or
early Campanian after the decline of thepair of var. denseplicatum and var. intermedium. As the actual mode of theadaptive strategy of organisms this explanation may be more reasonable.
Furthermore, the fact that var. tenuiliratum is rarely but actually obtained
from the Turonian is reasonably explained
only in this case.
Additional consideration ontransient polymorphism

Studies on transient polymorphism ofliving organisms are not as numerous(e. g., KETTLEWELL, 1955, 56; KOMAl etaI., 1950; KOMAI, 1956) in comparison withthose on balanced polymorphism (e. g.,
KOMAl and EMURA, 1955; CAIN and SHEPPARD, 1954; SMITH, 1973; on many spedesof butterflies and many species of Drosophila by many geneticists). This ismerely because long period is required
for a study of transient polymorphism.
Transient polymorphism is the polymorphism existing during the period whenan allele is being replaced by a superior
one (MA YR, 1970).
As the polymorphism mentioned here
is represented by two phenotypes (var.
tenuiliratum and the sexual couple of var.
denseplicatum), we can consider that apair of allele has the relation of dominant
and recessive. I consider both cases ofdominant mutation and of recessive mutation, since the gene produced by mutation
is usually recessive but disadvantageous(I avoid discussing the problems of neutral
theory here).

The decision whether a single gene canchange the morphology or not depends
on the. condition if the gene is a part ofthe polygenes or the major genes. Examples of the polymorphism owing to themutation of a single major gene arecommonly known.
Further, the rate of mutation is known
as low as 10- 5 to 10- 6 /1 gene locus(DOBZHANSKY, 1951). In population genetics the cases that the mutation recurrents
at a constant ratio p. in each generation[xt=xoe- 1tt , t: generation, Xo: frequencyof Al at the starting generation] and thatthe back mutation arises [Xt= p.~v +(1-p.-v)t(xo- p.~v)' v: rate of muta-tion from A2 to AI] (KIMURA, 1960;
HAYAMI, 1972, 73a, b) are considered. HereI discuss the change of the gene frequency on the assumption that the change iscaused not by recurrent mutation but by
natural selection as has commonly been
suppossed by evolutionists.
Case of recessive mutant gene: Assuming that var. tenuiliratum represents therecessive homozygote, I calculate the relative gene frequencies during the durationfrom the number of specimens (Tables
13, 14, Figs. 3, 11). The life span of thespecies is assumed as ten years or sobased on the rate of shell secretion calculated from the isotopic study on ammonites by STAHL and JORDAN (1969),
the origin of constriction of the molluscan
shell studied by UNO (1962) and theontogenetic pattern of constriction of var.
tenuiliratum (HIRANO, 1975). The stratigraphie range of var. tenuiliratu7n is fromthe Coniacian uwajimensis zone to the
Santonian amakusensis zone in Obira andis 9 m. y. in absolute age (HARLAND et
ai. ed., 1964). In Naibuchi it is from theuwajimensis zone to the Santonian japonicus zone and is 12 m. y. (Table 1).

685.

Phenotypic substitntion of Gaudryceras

253

Table 13. The change of the gene frequency from MM to Mh6.8 observedin Naibuchi samples. The case of dominant and that of recessin:
are both calculated. p is the frequency of the wild type gene.
Age

Phenotype
HorizonWild typem.y.
dCase of dominantCase of recessive

All

p

q

p

q

0.265
0.607
0.358
0.900

0.515
0.779
0.598
0.949

0.485
0.221
0.402
0.051

0.143
0.373
0.199
0.684

0.857
0.627

0
1

1. 0000.875

1. 000
0.935

0.000
0.065

1. 000
0.646

0.000
0.354

0
0

1. 0001. 0001. 0001. 0001. 0001. 000

0.000
0.000
0.000

1. 0001. 0001. 000

0.000
0.000
0.000

-76
Mh6;3
Mha-,8
Mh6a2
Mh6a1

Santonian

36
17
19

100
11

34

9
82

Coniacian

Mh5
Mh4

Turonian

Mh3
Mh2
Mhl

-I
7
88

94
Table 14.

The change of the gene frequency from Turonian to Santonian obserYedin Obira samples. The case of dominant and that of recessive are both
calculated. p is the frequency of the wild type gene.
Phenotype

Age

0.801
0.316

Zone

Wild type

Case of dominantCase of recessive

m.y.
d

All

p

q

p

q

-76
Santonianjaponicus
amakusensis

Coniacianmihoensis
uwajimensis

Turonianteshioensis
hobetsensis
labiatus

22

19
19

0.000
0.537

0.000
O. 733

1. 000
0.267

0.000
0.319

1. 000
0.681

40
10

3
1

0.930
0.909

0.964
0.953

0.036
0.0-15

0.736
0.699

0.264
0.301

35
60
5

0
0
0

1. 0001. 0001. 0001. 0001. 0001. 000

0.000
0.000
0.000

1. 0001. 0001. 000

0.000
0.000
0.000

0
82

88

94

Because the relative frequency of specimens is the average value in each zone,
the absolute age of the middle part ofeach zone should be employed for thefollowing calculation. The number ofthe generation follows that 6.10 5 in theformer and 9.10 5 in the latter. Here, therelative frequency of the dominant gene isp, and that of the recessive gene is q
(Tables 13, 14). When the wild type geneis Al and the mutant gene is A z, threegenotypes, AlAl' AlA2 and A2Az are

available. If A2 be recessive, the wild
type composed of AlAl or A l A 2. and themutant type A"A 2 would be observed.
This means that the relative frequencyof the mutant gene q of the mutant type
AzAz is calculated as the root of the ratioof the mutant type specimens.
Here I introduce the coefficient of selection, s (if the recessive individuals fitted
better than the dominant individuals to
the natural selection, s is negative) andthe following formula of the change ofHiromichi HIRANO

254_ sx(1-x)2
the gene frequency, Llx- 1- s(1-x)2' x:gene frequency, is obtained. When s ismuch smaller than 1, we can substitutethe above formula by the following equa.
dx _(1 -x )2 .
tlOn,c[i-sxIn my study the absolute value of s isalso assumed to be much smaller than 1.
To solve the above formula, we can apply

the transformation z=log.(l":J+(l~x)

Then, ~~ =sx(1-x)2
dz
becomes Tt= s and the value of z at

(KIMURA, 1960).

the t generation is given in the formula,
Zt=st+z o• Here Zo is the value of z at
the initial generation and t is the generation. The generation has already estimated and now I can obtain the value ofs. That is, in Obira s=-3.5·1O- 6 and in
Naibuchi s=-4.5·1O- 6 • The values arereasonably small as we can assume. fromthe fact that these two types replaced
through 9 m. y. or 12 m. y., and the values
are one figure smaller than that of Cryptopecten vesiculosus (HA YAMI, 1973b).
Case of dominant mutant gene: Likewise the following values are obtained in
Obira and Naibuchi, and the values of s
are the figures of 10- 6 in the two places.
s=3.9·10- 6
Obira
s=3.9·10- 6
NaibuchiDiscussion: As mentioned in the earlypart of this chapter, there are no data
which are directly comparable with theabove results.
Before going further I propose somevalues with regard to the fixation ofmutant genes. As the small s worked
effectively, the effective population size
(Ne) of the species is assumed to exceed
10 6 • The probability of fixation (U) is 2s
in the case of the complete dominanceand U = v2s/(rrN) in the case of the complete recessive.
The generation at which the relative
frequency of the mutant attains 0.5 iscalculated below.
1. Case of recessive
Obirat=6.3·10 5
Naibuchi t=3.2·10 5
2. Case of dominantObirat=1.0·10 5
Naibuchi t=9.2·10 5That is, the relative frequency of themutant gene attained 0.5 after about 1/10
total generations passed in Obira (1/14
in recessive case and 1/9 in dominantcase) and about 1/13 total generations(in dominant case) or 1/38 (in recessivecase) passed in Naibuchi.
In either case, dominant or recessive.
the analyzed results indicate that thewild type of C. denseplicatum did not
become extinct as it might appear but
the wild type was gradually replaced by
the mutant type, caused by the differenceof fitness for selection in the order of
10- 6 •
Furthermore, the mutant type of C.

Explanation of Plate 33
All figures x 0.8
1.

2.

3.

C. denseplicatum var. denseplicatum. I.471, from the Miho River, Naibuchi. Horizon: Mh3
Collected by M. KAWADA, a: ventral view, b: lateral view.
C. denseplicatum var. tenuiliratum. I-4034, from the Second stream of the eighteenth forestry district, Naibuchi. Horizon: Mhl·3. Collected by M. KAW ADA, a: ventral view, b: .
lateral view.
C. denseplicatum var. intermedium. I-185, from Makaushuppe, a branch of the SanushibeRiver, Hobets. Horizon: uncertain. Collected by Y ABE, H.

HIRANO:

Gaudryceras

Ib

Plate 33

685.
Age

C
0

Zone
Slbdivisionofin
Dominant mutant gene
Inoceramus Naibuchi
japonicus

C

III
III

U
III

Phenotypic substitution of Gaudryceras

amakusensis
mihoensis

Mh5

c

0
U

uwajimensis

Mh4teshioensis

Mh3

.c
0
....

hobetsensis

Mh2

t-

labiatus

Mhl

c

III

:l

Recessive mutant gene....

......-.

Mh6B
Mh60CB
MhSoc?
Mhfioc1255----...
••

~

~

I.

I

I.

oe-<

.....---.

I

~
I

10

•
•
•
o

t---€J

Io----e---........ •

I

•

•

I

I

I

I

8

•

I
I

•

0

0

0

•
•

• Naibuchi
0

Obira

0

0

0

02 0.4 0.6 0.8

1.0

0

0.2 0.4 0.6 0.8

1.0

Fig. 11. Historical change of the mutant gene frequency.
95% confidence interval is shown by a bar.

denseplicatum disappears in the middle or
early Campanian and C. striatum appears
about the time. In the detailed biostratigraphic studies (MATSUMOTO, 1943, 59a;
KANIE, 1966) C. striatum is said to overlap in time with the mutant type of C.
denseplicatum. The morphological resemblance between these two species has
already been mentioned by MATSUMOTO(1941). Transient polymorphism may havealso occurred in this case. If this assumption is true, the extinction of C. denseplica tum in the middle or early Campanianalso is not caused by a drastic change ofthe physical environment or similar kindsof other change.
Conclusion

The two nominal species, C. denseplicatum and C. intermedium, are explained
as a sexual dimorphic pair on the basisof morphometrical distinction found onlyin the adult shell, insignificant chronological change of the numerical ratio of
the specimens, commonly observed relation of coexistence in Hokkaido and

Sakhalien, the same geographic and thestratigraphic distribution. They are heredegraded to C. denseplicatum var. denseplica tum and C. d. var. intermedium,
respectively.
The ratio of the frequencies of anothernominal species, C. tenuiliratum, to var.
denseplicatum and var. intermedium shows
the same pattern through the duration in
the two areas, Obira and Naibuchi,
notwithstanding that the chronologicalchanges of the frequencies of the pair ofvar. denseplicatum and var. intermedilll1l
are in different patterns between these
two areas. In addition to this fact, in
virtue of the consideration of the morphometric analyses, the geographic andthe stratigraphic distribution, this nominal
species actually seems to belong to thesame species, C. denseplicatul1l, andtransient dimorphism is the most reasonable relation. Here C. tenlliliratul1l isdegraded to C. denseplicatu17l var. tenuiliratul1l.
The change of the relative gene frequency is obtained for the cases of thedominant mutant gene and the recessiveHiromichi HIRANO

256

mutant gene on the supposition that thechange is not caused by recurrent mutation but by natural selection, and thecoefficient of selection is obtained as thefigures of 10- 6 • Var. denseplicatum andvar. intermedium may have seemingly
become extinct, but they actually survived
till the end of Santonian or the early
Campanian. They were, however, gradually replaced by the individuals of
another phenotype (dimorphic pair) which
probably had higher fitness. This seems
to be significant in the evolutionary
studies not only of ammonoids but also
many other taxa.
Speciation is a function of population
size, the degree of initial variation of thegene pool in the peripheral isolate andthe degree of fitness of the peripheral
isolate. Therefore there can be several
models on evolution. Some cases may
fit phyletic gradualism and others may
fit punctuated equilibria. The present
case is an example of the evolutionarymode by the transient polymorphism, andit follows that the model proposed by
HAYAMI (in HAYAMI and OZAWA, 1975)
is supported as one of the major modelsof evolution not only by genetical theory
but also by palaeontological evidence.
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Explanation of Plate 34
All figures x 0.8
G. denseplicatum val'. denseplicatum (a fully grown up specimen). R2113-1, from the Obirashibe Riber, Obira •. Horizon: I. hobetsensis zone. Collected by HIRANO and TANABE.
2. G. denseplicatum val'. intermedium. Ventral view of the PI. 33, Fig. 3.

1.

Hate 34
HI RANG :Gaudryceras

685.

Phenotypic substitution of Gaudrycems

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Hiro?nichi HIRANO

258

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SCI-lINDEWOLF, O. H. (1954) : On development,
evolution and terminology of ammonoid
suture line. Mus. Compo Zool. Bull., Harvard Univ., vol. 112, p. 217-237.
SHIMIZC, S. (1935): The upper Cretaceous
cephalopods of Japan. Part 1. Jour. Shanghai Sci. Inst., sec. 2, vol. 1, p. 159-226.
SIMPSON, G. G. (1961): Principles of animal
taxonomy. Columbia Univ. Press, N. Y.,
Japanese ed. by Iwanami book Co., Tokyo,
272p.
SMITH, D. A. S. (1973): The population biology
of Lacuna paliidula(DA COSTA) and Lacuna

vincta (MONTAGU) in northeast England.
Jour. mar. bioi. Ass. U. K., vol. 53, p. 493520.
STAHL, W. and JORDAN, R. (1969): Generalconsideration on isotopic palaeotemperature determinations and analyses on Jurassic ammonites. Earth & Planet. Sci. lett.,
6, p. 173-178.
TANABE, K., HIRAl'O, H., MATSUMOTO, T.
and MIYATA, Y. (1977): Stratigraphy of
the upper Cretaceous deposits in the Obiraarea, northwestern Hokkaido. Sci. Repts.
Kyushu Univ., Ceol., vol., 12, no. 3, p.
181-202.
THOMPSON, D. (1917): On growth and form.
Cambridge Univ. Press, Japanese ed. byUniv. Tokyo Press, 1973, Tokyo, 215p.
U:--;o, Y. (1962): Studies on the aquicultureof Turbo cornutus SOLANDER with specialreference to the ecology and periodicityof the growth. Jour. Tokyo Univ. Fish.,
SPecial ed., vol. 6, no. 2, p. 1-76.
Y ABE, H. (1903): Cretaceous Cephalopoda
from Hokkaido Part 1. Jour. Coli. Sci.,
Imp. Univ. Tokyo, vol. 18, art. 2, p. 1-55,
pIs. 1-7.
YA:\IAMOTO, M. ed. (1973): Marine ecology.
Oceanography series, 9, Univ. Tokyo Press,
Tokyo, 213p.

1&Jt!JS.!IE;f.e7 ,/-'I:::t"1" Caudryceras Q)*!JUl'!.iiltJ!: B*t-;J:V:~:t: J: 1)f.4 Ght.::. C.
denseplicalum, C. intermediullZ, C. lenuiliratum Q)1(*f~")\"-C, lllf*Je1:~AQ)1:4P.JiJ!IJ'iE, :itl!JffiB'~· ~rfl¥J)j-;{ff, {ltiI{$:~.Lt~Q)t9tW~LJ.::.c::: 0, t'l* (1941) l~ti'i:fjl,j~hl'f,f:mCtJ:"? -C \,'t.::.J:ilt:;::::~Q)I*H~d)~(1zQ)~I~ID?fJJl-C ~ ::5::: c iJ~'FIJ"? t.::.o -ttd?'!?, C. denseplicatum
c C. inlermedium ft, :::h"j:-CI~~ilGh-C\"::5M~Je1:J:Q)%fL.H\&fj;J,Q){t!!K., ~&Q).
~,)j-;{ff:itl!J1iX&O:Jf.'ff1;:Q)-It ~1~~ff~Jt!JrI31~iili c -C Q)-'iEQ)lIl{$:~JtQ)*lM'l.J\ GM;I¥J=mi.
c 'J'1J1f)f ~ h::5 C. tenuiliratullZ it::: Q) jiIij~I~;ll<iili-t::5 Mmll¥J!f!fP&~:off L., ~tifli~'PfZ:'&'O:~:t:P'J~h~-c, J:ilt:;=mi. c Q){IIiI{$:~JtQ)I!t~~*Oi)::5 c jj'iJ C/~!J '/~~-th G Q)FI3'Q)~i*~ID?
1j)'j-t::5 t.::.ool-=', ::::")Q){&ID?~t~ -Ct9tWL. t.::.~*, C. tenuiliralum ftlliIilt:;=mi.c jj'iJ-;fi-C}/&lil!:0:::l¥J~mi.cL.-CID?fJJl-t::5Q)~.t~Jffil¥Jcmhhko~:::-C~~Q).~.~~I¥J~*~M~*.

f!l!:f 5L. ~9E1:I~")\"-C~~L.t.::.oExplanation of Plate 35
1.

C. denseplicalum var. inlermediullZ. N191-p, from the Santan River, Naibuchi.
Mh6a. Collected by T. MATSUMOTO X 0.8

Horizon:HIRANO:

Gaudryceras

Plate 35

Trans. Proc. Palaeont. Soc. Japan, N. S., No. 109, pp. 259-279, pIs. 36-38, April 30, 1978

686.

ADDITION TO THE MESOZOIC PLANTS FROM THE AKAIW AFORMATION (UPPER NEOCOMIAN), THE ITOSHIRO GROUP,CENTRAL HONSHU, INNER ZONE OF JAPAN*
T ATSUAKI KIMURATokyo Gakugei University, Koganei, Tokyo 18,1

and
SINJI SEKIDO
Komatsu Senior High School, Komatsu 923

Abstract. This paper deals with the additional palaeobotanical descriptions of newly
discriminated species to the Akaiwa flora formerly described by us (1976) in thepresent transactions. The newly described species are as follows; Gleichenites
nipponensis, Coniopteris saportana, Adiantopteris sewardii, A. toyoraensis, Raphaelia
diamensis, Dictyozamites efr. obliquus, Nilssonia schmidtii, Butefia? sp., Ginkgoites
paradianloides, Arclobaiera? sp., Elalocladus sp. C, E. sp. D, Protodammara sp. andCarpolithes sp. In addition, both Gleicheniles porsildii and Cladophlebis ex gr. wi!·liamsonii are redescribed with some emendation and additional remarks respectively.
It might be notable that Raphaelia diamensis, which has so far been regarded
as a Jurassic species, is now found from the Japanese Lower Cretaceous. The
occurrence of Coniopteris saportana, Dictyozamites efr. obliquus, Nilssonia schmidtii,
Ginkgoiles paradiantoides and Protodammara sp., is the first record in Japan.
After all, the Akaiwa flora is now consisting of 26 genera and ;:;3 species. As
formerly mentioned by us, both the Akaiwa flora (late Neocomian) and the underly.
ing Oguchi flora (early Neocomian, the main part of the "Tetori flora") in the Inner
Zone of Japan, are similar in composition to the coeval floras in V AKHRA~IEEV'S
Siberian Palaeofloristic Area, but are not so to those in the Outer Zone of Japan.

Afterwards we collected many more
specimens from the Bettokuzure point, ofthe upper layers of the Akaiwa Formation, the Itoshiro Group, the Tetori (orTedori) Supergroup, and found additional
fifteen new forms among them.
The present work deals with the description of these new forms, most ofwhich are common to the Late Jurassic
to the Early Cretaceous floras in the
VAKHRAMEEV'S Siberian Palaeofioristic
Area.

Introductory
Last year we described the Akaiwa
Flora with its comparison with the coeval
floras in the Outer Zone of Japan and in
the Siberian Palaeofloristic Area formerly
proposed by VAKHRA~IEEV, and mentioned its significance in the Mesozoic
floral change in Japan and her adjacentareas (KIMURA & SEKIDO, 1976b).

* Received July 20, 1977; read Jan. 21, 1977
at the annual meeting of the society, Tokyo.

259

260

Tatsnaki KIMURA and Sin}i SEKIDO--Table 1.

Composition and localities of the Akaiwa Flora(KIMURA & SEKIDO, 1977)
Localities

Genera & species

Equisetites spp. (stem and tubers)
Cleichenites nipponensis OISHI*
C. porsildii SEW ARD**
Coniopteris burejensis (ZALESSKY) SEWARD
C. saportana (BEER) V ACHRAMEE\'*
C. sp. cfr. C. hymenophylloides (BRONGNIART) SE\\"ARD
Birisia onychioides (V ASSILEVSKAJA & KARA-MuRSA)

BKA. spp. (A, B, C)

Onychiopsis elongata (GEYLER) YOKOYAMA
Sphenopteris ex gr. goepperti DUl\KER
S. kochibeana (YOKOYAMA) OISHI
Cladophlebis ex gr. denticulata (BROl\Gl\IART)

0
0
0

-

(MS)

0
0
0
0
0
0
0

0
0

0

0

0

0

0

0
0

0

•
• •
•
•• - 0

0
0

0

0

0
0
0

0

0
0

0

•• •

0

0

0

0

0

0

0

•
••
•

- - - -- -- - - -

0
0
0

0
0
0

0
0
0

0

0

• •• •-- • -0- -- -

0
0
0

--

0

0

0
0

0

0

0

0

0
0

0

0

0

0

0

0

- -- -- -

0

0

0
0

Cinkgoites digitata (BRONGNIART) SEWARD
C. huttonii (STERNBERG) BLACK
C. paradiantoides (SAMYLIl\A) KI~ICRA & SEKIDO*
C. sibirica (BEER) SEWARD
Cinkgoidium nathorstii YOKOYAMA
Pseudotorellia sp.

OZ- -- - - -- -0

C. spp.

Dictyozamites cfr. cordatus (KRYSHTOFOVICH) PRYNADA
D. cfr. obliquus SAMYLINA*
Nilssonia kotoi (YOKOYAMA) OISHI
N. lobatidentata V ASSILEVSKAJA
N. nipponensis YOKOYAMA
N. cfr. orientalis BEER
N. schmidtii (BEER) SEWARD*
Tetoria endoi KIMURA & SEKIDO
Butefia? sp.*

SI

0

0
0

C. ex gr. williamsonii (BRONGNIART) BROl\GNIART*
Raphaelia diamel1sis SE\\,ARD*
R. spp. (A, B)

000

NATHORST

C. (Osmundopsis) distans (BEER) KIMURA & SEKIDO

OG~

SA'dYLINA

Asplenium cfr. dicksonianum BEER
Adiantopteris sewardii (YABE) VASSILEVSKAJA *A. toyoraensis (O!SHI) VASSILEVSKAJA*

TOS

1 - - - - -- - - -

0

0
0

••

686.

Mesozoic plants from the Alcaiwa Formation

CzekaiZowskia sp.
Leptostrobus sp.
Podozamites angusti/olius (EICHIVALD) HEER
P. ex gr. lanceolatus (LIKDLEY & HUTTOI\') ERAV\
P. reinii GEYLER
Elatocladus spp. (A, E, C*, D*). PityophyllulI! lindstroemi NATHORST
Protodammara sp. *Xenoxylon latiporosum (CRAMER) GOTHAI\' (MS)
Carpolithes sp. * (Ginkgoites seeds?)

Seeds
Problematica

• ••
•

0
0
0

Arctobaiera? sp. *261- -- -- -- -

0
0
0
0
0
0
0

0

0
0

0
0
0

• ••
0

0

0

0
0
0

0

- - - - - -- - - -•0*; Additional forms here described to our previous work (KIMURA & SEKIDO, 1976b, p. 346,
tab. 2).
** ; Additional description and illustration to our previous work.
BK; Bettokuzure, southwestern slope of Mt. Hakusan (2,702 m), 5hiramine.mura, Ishikawa.gun,
Ishikawa Prefecture.
OS; Osugidani, Irahara, 5hiramine.mura, Ishikawa·gun, Ishikawa Prefecture.
T; Tamodani, Hambara, Izumi.mura, Ono.gun, Fukui Prefecture.
OG; Common or allied forms to the underlying Oguchi Flora (Early early Cretaceous in age).
51; Common or allied forms to the floras ranging from the Late Jurassic to the Early Cretaceous in age in VAKHRA~IEEV'S Siberian Palaeofloristic Area.
OZ; Common or allied forms to the coeval floras with the Akaiwa Flora in the Outer Zoneof Japan.
(open circles and solid ones showing common and allied forms respectively).

Table 1 shows the composition andlocalities of the Akaiwa Flora newlyedited by us, among which the species
with an asterisk and two asterisks aredescribed in this paper.
Acknow ledgements
We first express our sincere gratitude
to Dr. Thomas M. HARRIS, F. R. S., Professor Emeritus of the University ofReading, England for his very helpful
suggestions and kindest reading over thepresent manuscript.
We are indebted to Mr. Keiju YAMAZAKI, a member of the Komatsu City
Museum and many students of the Tokyo
Gakugei University for their invariable

help in collecting fossil plants. We also
give our thanks to Miss Tamiko OHANA,a graduate student of the Tokyo Gakugei
University for her kind help in drawing
the figures in this paper.
This study has been undertaken withthe aid from the Section of Cultural
Properties Protection, Board of Education, Ishikawa Prefecture.
Systematic description
Filicales
Family Gleicheniaceae
Genus Gleichenites SEWARD, 1910: 351

Gleichenites nipponensis OISHI

262

Tatsuaki KIMURA and Sinji SEKIDO
PI. 37, figs. 4, 5; PI. 38, figs. 3, 4;
Text.fig. 1

Gleichenites nipponensis OISHI; OISHI, 1940, p.
202, pI. 3, figs. 2, 3, 3a (Kaisekiyama, theRyoseki formation; Kuwashima, the Oguchi formation) ; KIMURA, 1958, p. 13, pI. 1,
figs. 2, 3; pI. 3, fig. 4; pI. 4; fig. 5; textfigs. 1, 2 (Mochiana, the Upper Jurassic
Kuzuryu group).

Description:-Ultimate (the last) pinnae
mostly long and narrow, nearly parallelsided, 4 mm wide, straight and attached
at interval of 7 mm to the axis at a wide
angle. Pinnules set closely, small, semicircular with broadly rounded apex, typically 1.3 mm long and 1.2 mm wide, uppersurface strongly convex, and attached by
the whole base perpendicularly to the
pinna axis; midnerve indistinct, forking
at its tip, sending off a pair of lateral,
forked once. Sori circular, 0.5 mm indiameter, consisting of five sporangia
with a prominent central placenta. Sorioccurring on each side of midnerve, but
often restricted to one on the acroscopic
side. (The details of sporangia not known).
Several fragments of penultimate pinnae
were newly obtained. Pi. 37, fig. 5 shows
possibly an apical portion of a penUltimate pinna in which ultimate pinnae are
reduced in length, their apical halves are
not segmented into pinnules but only
shallowly lobed and ending with acutely
pointed apex. Text-fig. 1 (a-d) shows
outline of sterile pinnae (la) and fertile
ones (lb) and position of sorus (lc-d).
Remarks:- The present specimens agree
well with the original ones described by
OISHI from Kuwashima (or Kuwajima) of
the Oguchi formation and also with thoseby KIMURA from Mochiana of the Kuzuryu group.
In the present material the sori eachcomposed of five sporangia are seenclearly but their cells were not visible.

The present species resembles Gleichenites vegagrandis HERBST (HERBST, 1962a,
p. 145, figs. 11, 14-15) and G. san-martini
HALLE (Ditto, p. 142, figs. 1-5, 12-13, 16)from the Lower Cretaceous (?) Baquero
formation, Patagonia and also G. juliensis
HERBST (HERBST, 1962b, p. 188, pi. 1, figs.
1-5; text-figs. 1, 2) from the Middle Jurassic of Patagonia. But Gleichenites nipponensis differs from the above three inits venation and fewer of sori on apinnule.
KRASSILOV regarded G. nipponensis as
the fertile frond of his cyatheaceous
Alsophilites nipponensis (KRASSILOV, 1967,
p. 113-117). But the Japanese specimens
clearly have Gleichenia-like sori.
Occurrence:- Rare.
SPecimens:-BK6-0l0 (A-F).

Gleichenites porsildii SEWARD
PI. 37, fig. 3; Text-fig. 2

Gleichenites aff. porsildii Seward; KIMURA,
1975, p. 70, pI. 7, figs. 1-3; pI. 8, fig. 2;
text-fig. 4-4a, b (Uppermost member of
the Tamodani formation); KIMURA &SEKIDO, 1976b, p. 351, pI. 36, fig. 2; textfig. 2 (Bettokuzure and Osugidani, theAkaiwa formation).

Description:-Proximal portion of afrond with three incompletely preserved
pinnae. Pinnules fertile, long and narrow,nearly parallel-sided, ending with rounded
apex, typically 0.8 cm long and 1.2 mm
wide at the middle portion, and the uppersurface strongly convex; margins lobed
except near apex, a basal pair of lobes
expanded. Midnerve of pinnule distinct,
persisting to the tip, sending off once orsometimes twice forking secondaries, thenumber of secondaries corresponding tothat of lobes. Sporangia all shed leaving,
the depression and the trace of a central
placenta on the centre of each lobe, but686.

Mesozoic plants j?·om the Akaiwa Formation

~

1c

~
I
o

~d

trY

1b

I

O.25cm

~
~·1a

-

263

o

O_5cm

o

O_25 cm~5cm I

2coo

Text-figs. 1-2: 1 (a-d) ; Gleichenites nipponensis OISHI. la; sterile pinnae (BK6-010A).
lb; fertile pinnae, showing venation and position of placentae (small solid circleS) (BK6010B). 1c-d; showing sori reconstructed from their depressions, enlarged partly from lb.
2 (a-d) ; Gleichenites porsildii SEWARD. 2a; sterile pinnae (BK6-063) _ 2b; sho\\-ing detailed
venation enlarged partly from 2a, each secondary nerve is forking once, then an apicalbranch forking again, but a proximal one does not so in general. 2c; fertile pinnae (BK6028) drawn from PI. 37, fig. 3 (BK6-028). 2d: showing detailed venation and position ofsori, and a sorus reconstructed from its depression, in which solid circles show placentae
and open circles with dotted line sh-JW the depression of sorus. (Parts drawn by dottedline are imaginary).

264

Tatsuaki KIMURA and Sil1Ji SEKIDO

judging from the shape of depression,
sori circular in form, 0.6 mm in diameterand probably consisting of several sporangia.
Sterile pinnules set closely, similar inform to fertile ones, but broader thanfertile ones and secondary nerves forked
twice.
Text-fig. 2 (a-d) shows outline of sterile
pinnae (2a), venation (2b), fertile pinnae
seen also in PI. 37, fig. 3 (2c) and detailsof a pinnule together with a restored
sorus (2d).
Remarks:-We describe two finer specimens than those formerly illustrated byus. Judging from its thick rachis, thepresent specimen shown in PI. 37, fig. 3
might represent the proximal portion ofa frond. Similar specimens, though representing the apical portions of fronds, topresent one were already described byus. The present and our former specimens are referable to those originallydescribed by SEWARD (1926, p. 76, pI. 6,
figs. 18-19, 24, 30) from the Cretaceousof Greenland, that by SEWARD & CONWAY(1935, p. 5, pI. 1, fig. 5) from the same
bed, those by KRASSILOV (1967, p. 107,
pI. 9, figs. 1-2) from the Lower Cretaceousof Southern Primorye, and those by BELL
(1956, p. 63, pI. 14, fig. 4; pI. 19, fig. 4 ;pI. 21, figs. 2, 3) from the Lower Cretaceous of Western Canada.
Cfr. Gleichenites porsildii recently described by SAMYLINA (1976, p. 21, pI. 2,
fig. 1) from the Lower Cretaceous (dated
as Aptian by her) of the Omsukchan
Coal-Field on the right bank of the Kolyma is indistinguishable from our sterile
specimens.
Occurrence :-Common.
Specimens:- BK6-028, BK6-063.
Family Dicksoniaceae
Genus Coniopteris BRONGNIART, 1849: 26

Coniopteris saportana (HEER)VACHRAMEEV
PI. 36, fig. 1; PI. 37, fig. 6; PI. 38, fig. 2;
Text-fig. 3

Dicksonia soportana HEER; HEER, 1876, p. 89,
pI. 17, figs. 1, 2; pI. 18, figs. 1-3 (JurassoCretaceous of the Bureja and the Amur).
Dicksonia gracilis HEER; HEER, 1876, p. 92,
pI. 17, fig. 3 (JUl'asso-Cretaceous of the
Bureja) .
Coniopteris saportana (HEER) V ACHRAMEEV ;VAKHRA~IEEV, 1958, p. 79, pI. 4, fig. 4;
pI. 5, fig. 3 (Lo\\"er Cretaceous of theLena) ; VAKHRA~IEEV & DOLUDEC-;KO, 1961,
p. 56, pI. 4, figs. 3, 4 (Jurasso-Cretaceousof the Bureja) ; LEBEDEv, 1965, p. 66, pI.
5, figs. 1-4; pI. 6, fig. 1; pI. 7, figs. 4-5;
text-fig. 15 (Upper Jurassic of the Zeia) ;SAMYLl:-.iA, 1964b, p. 61, pI. 10, figs. 3, 4a(Lower Cretaceous of the Zyrianka CoalField) ; 1976, p. 29, pI. 7, figs. 3-6 (Lower
Cretaceous of Omusukchan Coal-Field);
VASSILEVSKAJA, 1966, p. 52, pI. 1, fig. 3(Lower Cretaceous of the Lena).

Description :-Frond at least bipinnate.
Rachis comparatively thick, 2 mm acrossat the middle portion of frond (or penultimate pinna) with a prominent mediangroove on the upper surface and thinly
winged along both lateral sides. Pinnae
elongate-oval or elongate-lanceolate inform, flexible, more than 9 cm long and2.2 cm wide at the widest portion andattached alternately to the rachis at anangle of 35 degrees, then bending outwards, the distance being 1.25 cm. Pinna
axis slender and with a distinct mediangroove. Pinnules katadromic in order,
set closely, rhomboidal in form, acuminately pointed at apex, typically 1.2 cm
long and 3 mm wide at the widest portion, decurrent at base, distal half ofmargins serrate, serration typically 6-7
in number and directed forwards. Nerves
Sphenopteris-type, midnerve originatingnear the basiscopic base, slightly sinuous

686.

Mesozoic plants front the Akaiwa Formationand sending off 6-7 pairs of simple or
rarely once forking secondaries directed
forwards. The first basiscopic pinnules
specialized, triangular in form, the apex
sometimes bilobed and originating below
the base of the pinna axis and distinctly
decurrent to form wings along both sides
of main rachis. Fertile pinnae and pinnules, similar in form to sterile ones, but
mostly reduced in size, 0.4-0.5 cm longand 1.3 mm wide at the widest portion,in the largest one, more than 1 cm longand 7 mm wide at the widest portion.
Sori circular or oblong, variable in size,
0.2-1 mm across, one or rarely two in
number on the distal part of each serration, or on the distal part of the acroscopic secondary nerves in case of larger
pinnules.
Several specimens were obtained. PI.
36, fig. 1 shows a part of sterile frond
in which the first basiscopic pinnules areclearly seen. PI. 38, fig. 2 shows a fertile
pinna on the apical portion of a frond,
attached remotely to the fairly thickrachis, 2 mm across. PI. 37, fig. 6 shows
two fertile pinnules enlarged presumablyon the proximal portion of a frond, 1 cmlong and 0.5 cm wide, deeply lobed, inwhich sori are terminated at the distaledge of each acroscopic secondary nervein each lobe, and the laminae, except thesterile parts, are somewhat reduced.
Text-fig. 3 shows outline of sterile andfertile pinnae, pinnules and their venation,and presumable transverse section of arachis.
Remarks:-The present specimens agreewith Coniopteris saportana known fromvarious parts of East Siberia. The present specimens resemble HEER'S original
specimens in general outline of sterilepinnules and venation in which the secondaries are directed forwards, but withentire margins.
The present specimens agree closely265with those described by LEBEDEV (1965)
from the Upper Jurassic of the Zeia inoutline of pinnules with serrate margins,
venation, the form of first basiscopic
pinnules and the position of sorus.
This species has been regarded as oneof the characteristic ones in the V AKHRAMEEV'S Siberian Palaeo floristic Area. Thisis the first record of Coniopteris saportana
from Japan.
Occurrence:-Probably common.
Specimens:-BK6-031, BK6-037, BK6042, BK6-048, BK6-092.
Family Pteridaceae?
Genus Adiantopteris V ASSILEVSKAJA
1968: 49
We use Adiantopteris V ASSILEVSKAJA,
1968 instead of Adiantites GOEPPERT, 1836,
the meaning of which is confused. We
describe new material of Adiantopteris
sewardii and A. to),oraensis in which we
include 'Adiantites sp. D' of KIMURA &SEKIDO, 1976b. We rename Adiantites sp.
A, sp. Band sp. C of KIMURA, 1975 andKIMURA & SEKIDO, 1976b as Adiantopteris
sp. A, sp. Band sp. C respectively.
Adiantopteris sewardii CY ABE)V ASSILEVSKAJA
PI. 36, figs. 1, 2; PI. 37, fig. 7A; Text.fig. 4

Adiantites sewardi YABE; YABE, 1905, p. 39,
pI. 1, figs. 1-7 (Nagdong Group,. Korea),
fig. 8 (Kami-Uchinami, an equivalent of
the Oguchi formation) ; OISHI, 1940, p. 233,
pI. 7, figs. 1,5 (Iwaidani and Kuwashima,
the Oguchi formation), fig. 6 (a reproduction of Y ABE'S pI. 1, fig. 3) ; ]Ai\:ICHEi\: &KAHLERT, 1972, p. 966, pI. 1, figs. 2, 3, 5
(Jurasso.Cretaceous? of Mongolia).
Adiantites aff. sewardi YABE; VAKHRAMEEV,
1958, p. 83, pI. 8, figs. 2, 3 (Lower Creta·
ceous of the Lena).

Tatsuaki KIMURA and SinJ·i SEKIDO

266

~

3e

3g

I----l

o

I

I

0

1 em

I

I

2em

0

3d

I

0

t

O.25em

3a

I

O.5em

3f

o

O.5em

Text·fig. 3: Coniopteris saportana (HEER) VACHRAMEEV. a-d; sterile, e-f; fertile.
a-b; a part of sterile frond (BK6-037 and BK6-048). c; showing outline and venation of
normal pinnules, drawing from 3a. d; showing outline and venation of a first basiscopic
pinnule, drawing from 3a. e; a fertile pinna fragment on the distal part of a frond, showing outline and venation of pinnules, and position of sorus (BK6-031). f; a part of fertile
pinnule probably on the proximal portion of a frond, showing outline and Yenation, withdeeply lobed margins, and position of sorus (BK6-042). g; a presumable transverse sectionof rachis with a prominent median groove above, rounded below and lateral expansions due
to wings of laminae above.

686.

Mesozoic plants from the Akaiwa Formation

267

Adiantopteris sewardii (YABE) V ASSILEVSKAJA; KRASSILOV, 1967, p. 123, pI. 20,
figs. 1, 2 (Lower Cretaceous of Southern
Primorye).

Adiantopteris toyoraensis (OISHI)

Description :-Rachis slender, 0.5 mm
thick, with smooth surface, bearing subopposite lateral pinnules. Lateral pinnules
with short stalk, laminae somewhat inequilateral, broadly oblanceolate in form,
with cuneate base, distal margin irregularly double-serrate or lacerate, and distal
half of lateral margins shallowly serrate.
Nerves usually prominent, arising from
two in the stalk, branching throughout
and showing little tendency to form strong
marginal nerves, 16-18 in number per cm
in density at the middle part of lamina.
Apical pinnules and fructification not
known.
Several detached pinnules and one fragment of a frond were obtained. PI. 37,
fig. 7A (BK6-046) shows a fragment of afrond with three broken pinnules and PI.
36, fig. 2 (BK6-003) and fig. 1 show detached pinnules. Text-fig. 4 shows outlineof pinnules and their venation drawn from
BK6-046 and BK6-003 respectively.
Remarks:-This species is less common
in the Akaiwa Formation than the Oguchi
formation. The present specimens, thoughincomplete, agree with Y ABE'S original
specimens, especially with his pI. 1, fig. 3,
except the venation. All nerves appear
to originate from the top of stalk in
Y ABE'S illustration, while in the present
specimens, nerves are arising two in the
stalk, then branching throughout, as thenerves of Ginkgo biloba do. We imagine
that the veins are imperfectly represented
in YABE'S figures.
Occurrence :-Not common.
Specimens:-BK6-003, BK6-046 andmany small fragments of pinnules.

Adiantites toyoraensis OISHI; OISHI, 1931, p. 11,(name only) ; 1940, p. 235, pI. 7, figs. 2,
2a, 3 (non figs. 4, 4a) (Upper Jurassic
Kiyosue formation); JANICHEN & KAHLERT,1972, p.967, pI. 2, figs. 1,2 (JurassoCretaceous? of Mongolia).
Adiantites sp. D; KIMURA & SEKIDO, 1976b,
p. 358, pI. 36, fig. 4; text-fig. 8 (Osugidani, the Akaiwa Formation).

VASSILEVSKAJA
PI. 36, fig. 3; Text-fig. 5

Description :-Incompletely
preserved
pinnate lateral pinnules, bases missing.
Laminae small, ovate in form, with a
median sinus and with serrate outermargin, 2 cm long and about 1.5 cm wideat the widest portion. Nerves divergent
from the point of attachment, repeatedly
forking dichotomously, 18 per cm indensity at the middle part of lamina.
Fructification not known.
Text-fig. 5 shows two pinnate lateralpinnules and their venation.
Remarks:-The
present
incomplete
specimen agrees in pinnule outline andvenation with the original specimens described by OISHI from the Upper Jurassic
Kiyosue formation, Yamaguchi Prefecture.
This species resembles Adiantopteris
gracilis VASSILEVSKAJA known widelyfrom the Upper Jurassic-Lower Cretaceous of East Siberia (V ASSILEVSKAJA,
1957, 1966; V ASSILEVSKAJA & PAVLOV,
1963; SAMYLINA, 1976).
Occurrence :- Rare.
Specimen:- BK6-081.

Unclassified ferns
Form-genus Cladophlebis BRONGNIART,
1849: 105
From the Akaiwa Formation and its

Tats~wki J{li\WRA and Sinji SEKIDO

l 268

2cm

(r rn

2cm

6a

6b

~

ffrn/J
o
o

O.5cm

7c

o

2cm

Text-figs. 4-7. 4; Adiantopteris sewardii (YABE) VASSILEVSKAJA. 4a; a lateral pinnule
preserved almost completely, drawn from PI. 36, fig. 2 (BK6-003), showing outline andvenation of pinnule. 4b; a part of pinna with three incompletely preserved pinnules withshort stalk. 5; Adiantopteris toyoraensis (OISHI) VASSILE\,SKAJA, showing two lateral pinnules
and their venation, drawn from PI. 36, fig. 3 (BK6-0S1). 6; Cladophlebis ex gr. williamsonii(BRONGNIART) BRONGNIART. 6a; three detached pinnae drawing from PI. 37, fig. 2 (BK6033), showing general outline of pinnules. 6b; showing venation drawing from 6a. 7;
Raphaelia diamensis SEWARD. 7a; showing venation (BK6-017). 7b-c; showing outline ofpinnules, the first pair of lobes is distinctly specialized in form and each lamina is decurrent to axis to form a wing (BK6-025 and BK6-047).

686.

Mesozoic plants from the Akaiwa Formationequivalents, the following Cladophlebis
species have been known; Cladophlebis ex
gr. denticulata (BRONGNIART) NATHORST,
C. distans (HEER) YABE (non FONTAINE),
C. williamsoni (BRONGNIART) var. tenuicaulis THOMAS and C. sp.
We recently obtained good specimensfrom Bettokuzure of the Akaiwa Formation, assignable to C. ex gr. williamsonii
and regarded here C. williamsoni var.
tenuicaulis formerly described by us fromthe same locality as C. ex gr. williamsonii.
Cladophlebis ex gr. denticulata is similar
in form to C. ex gr. williamsonii, but it
is easily distinguishable from each otherby examining their venation; in C. ex gr.
denticulata, the secondaries are once forking dichotomously except the first pair
and in C. ex gr. williamson ii, they are
twice forking in general.
By our finding of its fertile pinnae fromthe Oguchi formation, Cladophlebis distans
is to be redescribed by us as Osmundopsis
distans (KIMURA & SEKIDO, 1977 MS) andalso C. sp. is at present to be referable
to some Gleichenites species (KIMURA &SEKIDO, 1977 MS).

Cladophlebis ex gr. williamsonii(BRONGNIART) BRONGNIART
PI. 37, fig. 2; Text·fig. 6

Cladophlebis williamsoni (BRONGNIART) BRO.
:"IGNIART var. tenuicaulis THOMAS; KIMU·
RA & SEKIDO, 1976b, p. 354, pI. 36, figs.
5, 6; pI. 38, fig. 6 ; text.fig. 5 (Bettokuzure,
the Akaiwa Formation).

HARRIS (1961) listed a large number ofcomparable specimens from many regions
including Japan and ranging from theUpper Triassic through the Jurassic.
V AKHRAMEEV (1958) and V AKHRAMEEV& DOLUDENKO (1961) gave Cretaceousreferences.

269

Description :-Sterile frond probably
bipinnate, unknown size. Pinnae set
closely, long and narrow, nearly parallelsided, more than 8 cm long and 1.6 cm
wide and attached to the rachis at anangle of 30-45 degrees. Pinnules set
closely, broadly triangular in form, falcate,entire, basiscopic margin usually rounded,attached by their whole base at a wide
angle, mostly with expanded base andsubacutely pointed apex, typically 1.2 cm
long and 0.6 cm wide at base. Midnerve
persisting to the tip, sending off twice
forking secondaries, 3 or 4 pairs on bothsides of a midnerve. (No fertile material
available).
Text-fig. 6a drawn from the specimen
shown in PI. 37, fig. 2 shows. outline ofpinnules and Text-fig. 6b shows detailed
venation.
Remarks:-It would be noteworthy thatsuch one of the older types of Cladophlebis
species bearing large-sized pinnules as
this species is fairly abundant in the
Akaiwa Flora, because they have not beenfound from the coeval floras in the Outer
Zone of Japan.
The present specimens agree in form
and venation with a common form ofsterile Todites williamsoni, though there
may be Cladophlebis species of this formin the Upper Jurassic and Lower Cretaceous.
Cladophlebis williamsoni var. tenuicaulis
described by us from the same locality
should now be included into the categoryof C. ex gr. williamsonii.
Occurrence :-Common.
SPecimens:-BK6-033, BK6-034 andmany pinna fragments.

Genus Raphaelia DEBEY &ETTINGSHAUSEN, 1859: 219
In our previous paper (1976b), we des-270

Tatsuaki KIMURA and Sinji SEKIDO

cribed Raphaelia sp. A and sp. B. Recently we obtained new material among
which we discriminated a well-known
Raphaelia diamensis.
Raphaelia diamensis SEWARD
PI. 37, fig. 1; PI. 38, fig. 1; Text.fig. 7
Raphaelia diamensis SEWARD: SEWARD, 1911,
p. 15, pI. 2, figs. 28, 29 (Middle Jurassicof Chinese Dzungaria); V AKHRAMEE\',
1958, p. 100, pI. 21, figs. 2-4; pI. 22, figs.
1-3; pI. 23, figs. 1-6; pI. 24, fig. 1 (Upper
Jurassic of the Lena); VAKHRAMEEV &DOLLDENKO, 1961, p. 75, pI. 6, fig. 5; pI.
27, fig. 1; pl. 28, fig. 1; pI. 30, fig. 4;
text·fig. 22 (Upper Jurassic of the Bureja) ;SA~IYLI"A, 1963, p. 79, pI. 9, figs. la, 2(Upper Jurassic of the Aldan) ; 1964b, p.
69, text·fig. 8 (Upper Jurassic of the
Zyrianka Coal.Field); LEBEDEV, 1965, p.
87, pI. 14, fig. 2; pI. 15, fig. 3 (Upper
Jurassic of the Zeia).
Raphaelia aff. diamensis SEWARD; SAMYLIKA,
1963, p. 80, pI. 2, figs. 8-11; pI. 7, fig. 5(Upper Jurassic of the Aldan).

Description :-Several incomplete pinna
fragments. Pinnae elongate-oval or elongate-lanceolate in form, about 1.5 em wideat the widest portion. Pinnules set somewhat remotely, elongate-triangular inform. 1 em long and 0.25 cm wide at base,bluntly or acutely pointed at apex, strongly constricted at base, then decurrent tothe axis to form a wing and attached ata wide angle to the axis, upper surface
strongly convex; margins distinctly lobed,
lobes 6-7 in number on each side, withrounded apex directed forwards, the firstpair of lobes mostly specialized, acroscopic ones rectangular in form, largest
in size, 0.27 mm long and 0.13 mm wideand less directed forwards, basiscopic
ones circular or triangular in form, sometimes reaching 0.2 mm in diameter, often
decurrent along the pinna axis to form awing, 0.3 mm wide, other lobes semicircular in form.
Midnerve distinct,
slightly sinuous, persisting to the tip,
sending off twice or once forking secondaries at an acute angle, each lobe receiving one secondary nerve. (No fertile specimens found).
PI. 38, fig. 1 and PI. 37, fig. 1 show theupper and lower surfaces of pinnae respectively and Text-fig. 7 shows outlineof pinnules and venation in detail.
Remarks:-The present specimens agreewith the original ones described by
SEW ARD from the Middle Jurassic ofChinese Dzungaria and those by several
Russian palaeobotanists from the Upper
Jurassic rocks in VAKHRAMEEV'S Siberian
Palaeofloristic Area in past two decades,
but the Siberian pinnules are somewhat
shorter and broader than those of ours.
In V AKHRAMEEV'S Siberian Palaeofloristic Area, this species appears to be
restricted in the Middle to Late Jurassic
floras, while in Japan this species is abundant in the early Neocomian Oguchi flora(KIMURA & SEKIDO, 1977 MS) and common
in the late Neocomian Akaiwa Flora, but
has not been recorded in the coeval floras
in the Outer Zone of Japan.
Occurrence :-Common.
Specimens:-BK6-017, BK6-025, BK6041, BK6-047.

Bennettitales
Genus Dictyozamites OLDHAM &MORRIS, 1963: 37
As was shown in detail in our previous
paper (KIMURA & SEKIDO, 1976a), theOguchi formation yields abundant andvaried Dictyozamites species, while fromthe superjacent Akaiwa Formation, only
D. cfr. cordatus (KIMURA & SEKIDO, 1976b)
and a new type here described resembl-

686.

Mesozoic plants from the Akaiwa Formation

ing D. obliqllllS are known in rare occurrence.
Dictyozamites cfr. obliqllllS SAMYLINA
PI. 38, fig. 5; Text·fig. 8Comparable specimens: Dictyozamites obliquus
SA:\IYLINA; SAMYLINA, 1964a, plate, figs.
10, 11 (Lower Cretaceous of Central Pri·
morye).

Description :-Isolated pinnae, elongatetriangular in form, upper margin straightand lower one arched, both apex andbase missing, more than 3 cm long and
0.8 cm wide at basal part. Nerves fine,anastomosing to form fine meshes, upper
nerves straight, parallel to the upper
margin but lower nerves divergent to thelower margin.
Text-fig. 8 drawn from one of thespecimens shown in PI. 38, fig. 5 show
venation in detail.
Remm'ks:-The present specimens arecharacterized by the nerves in which
upper ones are straight and parallel tothe upper margin and lower ones aredivergent. Such nerves as in the present
specimens has not yet been recorded
among the known Dictyozamites species,
except D. obliquus.
Therefore the present specimens might
be referable to Dictyozamites obliquus
originally described by SAMYLINA fromthe Lower Cretaceous of the Bikin Riverarea, Central Primorye, but we here
reserve identifying the present ones fully
to SAMYLINA'S species because they are
too imperfect.
Occurrence :-Rare.
Speci71len:-BK6-090 (one slab only).

Cycadales
Genus Nilssonia BRONGNIART, 1825: 200

271

From the Akaiwa Formation, the following Nilssonia species have been described; Nilssonia kotoi (YOKOYAMA) OISHI,
N. lobatidentata V ASSILEVSKAJA and N_
nipponensis YOKOYAMA. In addition, we
here describe Nilssonia schmidtii (HEER)SEWARD.
These Nilssonia species are common to
those of the coeval floras in V AKHRAMEEV'S Siberian Palaeo floristic Area,
except N. kotoi. But N. kotoi is similar
in form to N. sinensis Y ABE & OISHI
known from the Jurassic of Northern
China and N. borealis SAMYLINA fromthe Lower Cretaceous Siliap formation in
the Zyrianka Coal-Field.
These Nilssonia leaves from the Akaiwa
Formation are smaller in size in generalthan those from the underlying Oguchi
formation.

Nilssonia schmidtii (HEER) SEWARD
PI. 38, fig. 6; Text-fig. 9

Anomozamites schmidtii HEER; HEER, 1876,
p. 100, pI. 23, figs. 2, 3; pI. 21, figs. 4-7(Jurasso.Cretaceous of the Bureja and theAmur).
Nilssonia schmidtii (HEER) SEWARD; SEWARD,
1912, p. 27, pI. 2, figs. 11, 12, 14 (JurassoCretaceous of the Tyrma and the Umalta) ;KRYSHTOFOVICH, 1916, p. 114, pI. 10, fig.
5 (Lower Cretaceous of Southern Primorye); V AKHRAMEEV & DOLlJDEl'KO,
1961, p. 96, pI. 43, figs. 5, 6 (JurassoCretaceous of the Bureja) ; LEBEDEv, 1965,
p. 92, pI. 22, fig. 3b; pI. 23, fig. 2; pI. 24,
fig.. 1 (Upper Jurassic of the Zeia).

Description :-Several isolated leaf-fragments. Leaves more than 4.7 cm longand 2.8-1.6 cm wide at the middle portionof lamina. Lamina covering the uppersurface of rachis, irregularly segmented,
segments 0.5-1.3 cm wide, quadrilateral inform, lateral and distal margins of narrow272

Tatsuaki KIMURA and Sinji SEf(IDO

2em

o

8

"ill
I

o

I

lem

o

I

o

I
1. em

o

686. Mesozoic plants from the Akaiwa Formation
segments rounded, but irregularly andbroadly undulated in broad segments.
Nerves fine, simple, parallel, 26-34 per
cm in density.
Remarks:-The present specimens arereferable to Nilssonia schmidtii in generaloutline. Such specimens regarded as
Nilssonia schaumburgensis by KRASSILOV(1967) from the Lower Cretaceous ofSouthern Primorye as his pI. 57, figs. 3,
4, 6 resemble the present ones, but they
are distinguishable from the present onesin that in KRASSIL ':lV'S specimens theincisions of laminae are mostly not reaching to the rachis, or if do so, the segments are different in form those of N.
schmidtii.
Several specimens regarded by us as
Nilssonia nipponensis from the same
locality (KIMURA & SEKIDO, 1976b, p. 361,
pI. 37, fig. 2; text-fig. 17) are similar inform to the present ones but the distal
margins of their segments are mostly
finely dentate and not rounded as thoseof the present ones.
Occurrence :-Common.
Specimens:-BK6-018, BK6-044, BK6080.

Unclassified cycadophyte
Genus Butejia DOBRUSKINA, 1964: 135
In 1964, DOBRUSKINA established thisgenus as a new cycadophyte, based on apart of HEER'S Podozamites ensiformis(HEER, 1878, p. 6, pI. 2, figs. 5, 6) and
PRYNADA'S Glossozamites ensiform is, in-273

cluding YOKOYAMA'S Glossoza71lites hoheneggel'i with her some doubt, and described Butejia ensiform is (HEER) (p. 135,
pI. 12, figs. 1-3), from the Upper Jurassic
in the upper course of Amur.
This genus is a form-genus known only
by its external pinnate fronds. The external appearance of its pinnae reminds
us of some Podozamites leaves, but it isgenerally distinguished from Podozamites
by its apparently dichotomously forking
nerves near the base.
In 1965 LEBEDEV described Butejia burejensis from the Upper Jurassic along theZeia, including as synonymy PRYNADA'S
Glossozamites burejensis and DOBRUSK~NA'S
Butejia ensiform is excluding her pI. 12,
fig. 2.
Very recently SAMYLINA (1976) described Butejia obliqua as a new species
from the Lower Cretaceous bed (dated
as Aptian by her) of the Omsukchan
Coal-Field in the right bank of Kolyma.
Butejia? sp.
Text-fig. 10

Description :-A detached pinna, basemissing, elongate-ovate in outline, 8.3 cm
long and 3.4 cm wide ,at the widest portion, apex presumably rounded: Nerves
originating radially from the small area
at base, dichotomously forking near base~parallel on the most part and converging
near apex, apex unknown, 16 per cm indensity at the middle portion of lamina. 'Text-fig. 10 shows pinna outline andvenation.

Text-figs. 8-12. 8; Dictyozamites cfr. obliquus SA;\IYLlNA, showing venation in detail,drawing from One of the incomplete pinnae shown in PI. 38, fig. 5 (BK6-090). 9,; Nilssonia
schmidtii (HEER) SEWARD, showing outline of segments and venation, drawing partly
from BK6-018. 10; Butefia? sp., showing pinna outline and venation, drawing from BK6029. 11; Ginkgoites paradiantoides (SAMYLINA), sh'owing venation and general outline oflamina, drawing from PI. 38, fig. 8 (BK6-035). 12; Arctobaiera? 'sp., showing venation,
drawing from PI. 38, fig. 9 (BK-106).

274

Tatsuaki KIMURA and Sinji SEKIDO

Remarks:-The present pinna would
belong to Butefia owing to its venation.
But it does not agree both in external
outline and in density of nerves withsuch three species hitherto known in
VAKHRAMEEV'S Siberian Palaeofloristic
Area as B. burejensis, B. ensiformis andB. obliqua. However, owing to the incompleteness of present material, we atpresent regard the present one hastily as
Butefia? sp., though we should make herewith our anxiety an additional remarkthat the present one resembles closely
such Ferganiella species regarded by
Russian palaeobotanists as having Podozamites affinity, as F. LanceoLata BRICK described by BARANOV A et al. (1975, p. 133,
pl. 34, figs. 7, 8) from the Jurassic of theeastern part of Caspian Basin.
Occurrence :- Rare (at present).
SPecimen:- BK6-029.
Ginkgoales
Genus Ginflgoites SEWARD, 1919: 10
In addition to such Ginkgoites species
as G. digitata, G. huttonii and G. sibirica
described by us (KIMURA & SEKIDO, 1976b)from the Akaiwa Formation, a new typeleaves referable to Ginflgoites paradiantoides are described here. Following
SEW ARD (1919), we have used the genericname Ginkgoites, instead of Ginkgo usedby modern palaeobotanists.

Ginkgoites paradiantoides(SAMYLINA) n. comb.
PI. 38, figs. 7, 8; Text-fig. 11
Similar specimens: Ginkgo paradiantoides
SAYMYLINA; SA~IYLINA, 1967, p. 138, pI.
2, figs. 2-5; pI. 3, figs. 1-11; pI. 4, figs.
9-10; pI. 6, fig. 7a; pI. 8, fig. 7b (Lower
Cretaceous of the Zyrianka Coal-Field).
Ginkyo pluripartita SClIIMPER; SA:vIYLINA13,
1964, p1.l7, fig. 2b (Ditto).

Description :-Leaves long petioled, petiole 4-5cm long. Laminae semi-circular witha basal angle of 180 degrees, divided by a
deep median sinus reaching to the top of
petiole into two halves with truncated orirregularly lobed apical margin. Nerves
divergent, dichotomously forking at alllevels on the apical half of lamina.
Remarks:-It is unfortunate that wecannot give details of the cuticle because
it is not preserved in the present flora.
The present specimens would be referable almost to SAMYLINA'S Ginkgo paradiantoides described from the Zyrianka
Coal-Field.
Occurrence :-Not rare.
SPecimens:-BK6-035, BK6-085.
Czekanowskiales
Genus Arctobaiera FLORIN, 1936: 118

Arctobaiera? sp.
PI. 38, fig. 9; Text-fig. 12

Explanation of Plate 36
1. Coniopteris saportana (HEER) VACI-IRA~1EE\'; sterile part of a frond; in association with two
incomplete pinnules of Adiantopteris sewardii (YABE) VASSILEVSKA)A. (BK6-037), x 2.
2. Adiantopteris sewardii (YABE) VASSILEVSKA)A; one nearly complete pinnule and two incompletely preserved pinnule bases. (BK6-003), x 2.
3. Adiantopteris toyoraensis (OISI/I) VASSILEVSKA)A; (= Adiantites sp. D in KIMURA & SEKIDO,
1976b) ; two pinnate sterile pinnules. (BK6-081), x 2.
4-7. Protodammara sp. ; cone scales. (4; BK6-001, 5-7; BK6-040), x 3.
8-9. Carpolithes sp. ; seeds of Ginkgoites?; (BK6-040), x 3.

KIMURA and SEKIDO:

Mesozoic plants from the Akaiwa Formation

Plate 36

686.

Mesozoic plants from the Akaiwa Formation

275

Description :-A fragment of a leafbundle composed of four segments, uniting near base. Segments long and narrow,about 7 cm long, variable in width, ranging 5-Smm wide at the middle portion,
overlapping each other laterally, narrowing gradually towards the unknown baseand abruptlY towards unknown apex.
Nerves 5-7 in number at basal part, thendichotomously forking, as many as twice
in number at middle portion, not converging at apex. Text-fig. 12 drawing fromPI. 3, fig. 9 shows outline of leaves andtheir venation.
Remarks:-One specimen with its counterpart was obtained. JUdging from its
form, this specimen might represent aleaf-bundle consisting of more than four
segments and might belong to Arctobaiera
or Phoenicopsis of Czekanowskiales. At
present we provisionally place it Arctobaiera? sp.
The present specimen would remind us
of Arctobaiera florinii originally describedby LEBEDEV (1974, p. SO, pI. 20, fig. 2;
pI. 21, figs. 1-4; pI. 22, fig. 1 ;text-fig. 37)
from the Lower Cretaceous of Western
Priokhotie.
Occurrence:- Rare.
Specimen:-BK-106 (its counterpart,
BK -133, collected by C. SMILEY, Professorof the University of Idaho, U. S. A., in1974).

Description:- A single specimen of aconiferous shoot. Leaves dorsiventrally
set closely, long and narrow, nearlyparallel-sided throughout, constricted atbase, very shortly petioled, with bluntly
pointed at apex, typically 0.7 cm long and
0.9 mm wide, attached to the axis at anangle of about 60 degrees, and longitudinally traversed by an indistinct median
nerve.
Remarks:-Though we have nothing to
say about its affinity because of the incompleteness of material, the present
specimen would remind us of such taxodiaceous genera as Sequoia or Taxodium,so far as its external appearance is concerned.
Occurrence :-Fine fragments are common.
SPecimen:- BK6-009.

Coniferales

Elatocladus sp. D

Besides varied and abundant Podozamites species, a few conifer remains suchas Elatocladus sp. A and sp. B, and Pityophyllum lindstroemii have been reported in
the Akaiwa Flora (KIMURA & SEKIDO,
1976b). In addition, we describe here two
types of coniferous shoots, and several
coniferous cone-scales probably belonging
to a same species but uncertain affinities.

PI. 38, fig. 11

Conifers in the Akaiwa Formation haveusually been neglected because the specimens give little palaeobotanical informations, but we point out that there are
fairly numerous species in the flora.

Form-genus Elatocladus HALLE, em.
HARRIS, 1969: 249
Elatocladus sp. C
PI. 38, fig. 10

DescriptiOlL'- A single incomplete coniferous shoot. Leaves linear lanceolate
in form, constricted at base and decurrent
to the axis, bluntly pointed at apex, 0.5.
cm long and 1 mm wide at the widest
portion, and longitudinally traversed by aprominent median nerve.

276

Tatsuaki KIMURA and Sinji SEKIDO

Remarks:-Palissya sp. described by
YOKOYAMA (1889, p. 64, pl. 9, fig. 11) from
Kuwashima (formerly Shimamura) of the
Oguchi formation somewhat resembles thepresent one in external appearance.
The present specimen is included in
Elatocladus in the sense in which thatcomprehensive genus was proposed by
HALLE.
Occurrence:-Fine fragments of leaves
are common.
Specimen:- BK6-039.

and Dammara minor by HOLLICK (1906)
from the Cretaceous of New York. But
these American specimens differ from thepresent ones in having apiculate apices.
Full analysis and discussion of thepresent specimens will be made after amore complete study of our new material.
This generic name, Protodammara itself
does not always mean its araucarianaffinity.
Occurrence :-Not rare.
Specimens:- BK6-00l, BK6-040.

Form-genus Protodammara HOLLICK &JEFFREY, 1906: 199

Unclassified seedProtodammara sp.

Form-genus Carpolithes SCHLOTHEIM,
1820: 418

PI. 36, figs. 4-7

Carpolithes sp.

Description :-Several detached kite-likecone scales. Cone scales 0.8-1.0 cm longand 0.7-0.9 cm wide above, abruptly narrowed from about middle to the base, notapiculate but broadly undulate terminally,
seed scars three in number, crescenticallyarranged above the middle and approximately in the broadest part of the scale,with the central one slightly higher up
than the laterals.
Remarks:-In external appearance, thepresent specimens somewhat resemble
Protodammara speciosa originally described by HOLLICK & JEFFREY (1906, 1909)

PI. 36, figs. 8, 9

Description :-SeveraJ incomplete seeds.
Seeds or seed-stones ovate, sharply edged,
rounded at base and sharply beaked atapex, 0.9 cm long and 0.6 cm wide at thewidest portion.
Remarks:-The present specimens resemble the following in external appearance; seeds regarded by HEER (1876, p.
58, pI. 11, figs. 13-16) as belonging to
Ginkgo sibirica from the Jurassic of UstBalei; Carpolithes ginkgoides by YOKOYAMA (1889, p.65, pI. 10, figs. 20-23) from

Explanation of Plate 37
1. Raphaelia diamensis SEWARD; a pinna fragment (back view) ; (BK6-025), x 3.
2. Cladophlebis ex gr. williamsonii (BROJ'iGNIART) BRONGNIART; sterile parts of fronds piled up
together. (BK6-033), x 1.
3. Gleichenites porsildii SEWARD; fertile pinnae with comparatively thick rachis. (BK6-028), x 2.
4-5. Gleichenites nipponensis OISHI; incomplete fertile pinna fragments. (BK6-010), x 2.5.
6. Coniopteris saportana (HEER) V ACI-IRAMEEV ; fertile pinna fragment. (BK6-042), x 3.
7. A; Adiantopteris sewardii (Y ABE) V ASSILEVSKAJA; two pinnate pinnules attached to therachis with short stalks.
B; Nilssonia lobatidentata VASSILEVSKAJA; (for details, see KIMURA & SEKIDO, 1976a, b).
(BK6-046), x 2.

KIMURA and SEKIDO:

Mesozoic plants from the Akaiwa Formation

Plate 37

686.

Mesozoic plants from the Alcaiwa Formation

Ozo of the Oguchi formation apart fromtheir long beaks as shown in his figures;
Allicospennum burejense by KRASSILOV(1972, p. 39, pI. 5, figs. 8-10; text-fig. 5d,g) from the Jurasso-Cretaceous of Bureja
Basin; seeds regarded by HARRIS et a!.
(1974, p. 72, fig. 22C, D) as belonging to
Ginkgo huttoni from the Middle Jurassicof Yorkshire.
Thus it would be quite possible that thepresent specimens belong to Ginkgoites.
Occurrence :-Rare.
Specimen :-BK6-040 (one slab only).

References
R-\RANOVA, Z. E., KIRICHKOVA, A.I. & ZAUER,
V. V. (1975): Stratigraphy and flora fromthe Jurassic of the eastern part along the
Caspian Basin. VNICRI, Leningrad, Bull.
332, p. 1-190, incl. pis. 1-34. (in Russian).
BELL, W. A. (1956): Lower Cretaceous floras
of Western Canada. Ceol. Surv. Canada,Mem. 285, p. v+1-331, incl. pis. 1-85.
DOBRUSKINA, I. A. (1964): New Jurassic
cycadophyte·s from the upper course of
Amur. jounl. Palaeont., Acad. Sci. USSR,
1964-no. 2, p. 132-141, pis. 12-13. (inRussian).
HARRIS, T. M. (1961) : The Yorkshire Jurassic
flora I. Thallophyta-Pteridophyta. Brit.
A;fus. (Nat. Hist.), p. ix+1-212.
- - (1969): Naming a fossil conifer. j. Sen
Mem. Vol., Bot. Soc. Bengal, p. 243-252.
- - , MILLINGTON, W. & MILLER, J. (1974):
The Yorkshire Jurassic flora, IV. Ginkgoales and Czekanowskiales. Brit. Mus.
(Nat. Hist.), p. viii+1-150, pis. 1-8.
HEER, O. (1876): Beitrage zur Jura-Flora
Ostsibiriens und des Amurlandes. Mem.
Acad. Imp. Sci., St.-Petersb., ser. 7, T.
22, no. 12, p. 1-122, pis. 1-31 (Fl. foss.
arct., 4-2).
---- (1878) :Beitrage zur fossilen Flora
Sibiriens und des Amuriandes. Ibid., T.
25, no. 6, p. 1-58, pis. 1-15 (Fl. foss. arct.,5-2) .
HERBST, R. (1962a): Sobre les especies de277

Cleichenites de los sedimentos Baqueroensis de Santa Cruz, Patagonia. Ameghiniana, T. 2, nr. 8, p. 141-148, pis. 1-3.
- - (1962b): Cleichenites juliensis n. sp. delJurasico Medio de Santa Cruz, Patagonia.
Ibid., nr. 10, p. 187-190, pI. 1.
HOLLICK, A. (1906): The Cretaceous floraof Southern New York and New England.
Mon. U. S. Ceol. Surv., vol. 50, p. 1-219,
incl. pis. 1-40.
- - & JEFFREY, E. C. (1906): Affinities ofcertain Cretaceous plant·remains commonly referred to the Dammara andBrachyphyllum. Amer. Nat., vol. 40, p.
189-216, pis. 1-3.
- - & - - (1909): Studies of Cretaceousconiferous remains from KreischerviIIe,
New York. Mem. N. Y. Bot. Card., vol.
3, p. 1-76, pis. 1-29.
Jii.HNICIIEN, H. & KAHLERT, H. (1972): Vbereine mesozoische Flora aus der mongol ischen Volksrepublik. Ceol., Jahr. 21, H.
8, p. 964-1001, incl. pis. 1-6.
KIMURA, T. (1958): On the Tetori flora (Pt.
1). Mesozoic plants from the Kuzuryu
Subgroup, Tetori Group, Japan.
Bull.
Sen. High Sch., Tokyo Univ. Educ., II-2,
p. 1-47, pis. 1-4.
- - (1975):
Middle·late early Cretaceous
plants newly found from the upper courseof the Kuzuryu River area, Fukui Prefecture, Japan. Trans. Proc. Palaeont.
Soc. japan, N. S., no. 98, p. 55-93, pis.
5-8.
- - & SEKIDO, S. (1976): Dictyozamites andsome other cycadophytes from the early
Lower Cretaceous Oguchi Formation, theItoshiro Group, Central Honshu, Japan.
Ibid., no. 101, p. 291-312, pIs. 30-32.
- - & - - (1976b): Mesozoic plants fromthe Akaiwa Formation (Upper Neoco·mian), the Itoshiro Group, Central Hon·shu, Japan. Ibid., no. 103, p. 343-378,
pis. 36-39.
- - & - - (1977MS):
The Oguchi Flora(Early early Cretaceous) in the Inner
Zone of Japan.
KRASSILOV, V. A. (1967): Early Cretaceous
flora from Southern Primorye and its
significance for stratigraphy. Far East

278

Tatsuaki KIMURA and Sinji SEKIDO

Ceol. Inst., Siber. Br., Acad. Sci. USSR,
Moscow, p. 1-248, pIs. 1-93. (in Russian).
- - (1972): Mesozoic flora from the Bureja(Ginkgoales and Czekanowskiales). Far
East Ceo!. Inst., Far East Sci. Centre,
Acad. Sci. USSR, p. 1-151, incl. pIs. 13-1. (in Russian).
KRYSHTOFOVICH, A. N. (1916): Material for
the Jurassic flora of Ussuriland. Trav.
Mus. Ceol. Min., St.-Petersb., vol. 2, no.
-1, p. 81-140, pIs. 7-11.
LEBEDEv, E. L. (1965) : Late Jurassic flora from
Zeia and boundary between Jurassic andCretaceous. Ceol. Inst., Acad. Sci. USSR,
Trans., vol. 125, p. 1-142, pIs. 1-36. (inRussian).
- - (1974): Albian flora and Lower Cretaceous stratigraphy of West Priokhotie.
Acad. Sci. USSR, Trans., vol. 254, p. 1147, incl. pIs. 1-31. (in Russian).
OISI-II, S. (1931): The Mesozoic plants, inIwanami's Geological and Palaenotological
Series, Tokyo. p. 1-91. (in Japanese).
- - (1940): The Mesozoic floras of Japan.
Journ. Fac. Sci., Hokkaido Imp. Univ., vol.
5, nos. 2-4, p. 123-480, pIs. 1-48.
SAMYLlNA, V. A. (1963): Mesozoic flora of
the lower course of the Aldan River.
Palaeobot., Komalov Bot. Inst., Acad. Sci.
USSR, ser. 8 (Palaeobot.), vol. 4, p. 59138, pIs; 1-37. (in Russian).
-"-" (1964a): Lower Cretaceous plants fromthe Central Sikhota-Alin. Jourii. Bot.,
Acad. Sci. USSR, vol. 49, p. 1286-1287.
(in Russian).
- - (1964b): Mesozoic flora of the area tothe west of the Kolyma River (Zyrianka
Coal-Basin), Pt. 1. Palaeobot., Koma/ov
Bot. Inst., Acad. Sci. USSR, ser. 8 (Palaeobot.), vol. 5, p. 41-78, pIs. 1-18. (inRussian).
- - (1967): Ditto. Pt. 2 Ginkgoales, Coniferales, General Chapters. Ibid., vol. 6,
p. 133-175, pIs. 1-14. (in Russian).
- - (1976): The Cretaceous flora of Omsukchan (Magadan District). Komalov Bot,
Inst., Acad. Sci. USSR, Leningmd, p. 1206, incl. pIs. 1-48. (in Russian).
SEW ARD, A. C. (1910): Fossil plants, A textbook for students of botany and geology,
vol. 2, p. xxii+1-624. Cambridge.
" - (1911): Jurassic plants from Chinese
Dzungaria, collected by Prof. OBR UTSCHEW.
Mem. Com. Ceol., N. S., L. 75, p. 31-61,
pIs. 1-7.
- - (1912): Jurassic plants from Amurland.
Ibid., L. 81, p. 17-34, pIs. 1-3.
- - (1919): Fossil plants, A text-book forstudents of botany and geology, vol. 4.
p. xvi+1-543, Cambridge.
- - (1926): The Cretaceous plants-bearing
rocks of Western Greenland.
Philos.
Trans. Roy. Soc., London, ser. B, vol. 215,
p. 1-174, pIs. 4-12.
- - & CONWAY, V. (1935): Additional Cretaceous plants from Western Greenland.
K. svensk. Vet.-Acad. Hand!., Stockholm,
Bd. 15, no. 3, p. 1-41, pIs. 1-6.
V AKHRAMEEV, V. A. (1958): Stratigraphy
and fossil plants from the Jurassic andCretaceous deposits ot" the Vi lui Basinand Vercho jansk Foredeep. Reg. Stratigr.

Explanation of Plate 38
1. Raphaelia diamensis SEWARD; pinnules with convex upper surface (surface view). (BK6-047),x2.
2. Coniopteris saportana (HEER) V ACHRAl\IEEV ; an incomplete fertile pinna. (BK6-031), x 3.
3-4. Cleichenites nipponensis OISHI; incomplete fertile pinna fragments. (BK6-010), x 2.5.
5. Dictyozamites cfr. obliquus SAMYLlNA; two incomplete pinnae isolated. (BK6-090), x 2.
6. Nilssonia schmidtii (HEER) SEWARD; (BK6-044), x 2.
7 -8. Cinkgoites paradiantoides (SAMYLINA) comb. nov.: (7; BK6-0SS, 8; BK6-035), xL
9. Arctobaiera:? sp.; (BK-106), xL
10. Elatocladus sp. C; (BK6-039), x 3.
11. Elatocladus sp. D; (BK6-009), x 2.

KIMURA and SEKIDO:

Mesozoic plants from the Akaiwa Formation

Plate 38

686.

Mesozoic plants from the Akaiwa Formation

USSR, Ceol. Inst., Acad. Sci. USSR, vol.
3, p. 1-128, pis. 1-32 (in Russian).
- - & DOLuDE;-;Ko, M. P. (1961):
Upper
Jurassic and Lower Cretaceous flora of
the Bureja Basin and its significance forstratigraphy.
Ceol, Inst., Acad. Sci.
USSR, Trans., vol. 54, p. 1-135, pis. 1-60.
(in Russian).
VASSILEVSKAJA, N. D. (1957): Three new
fern genera from the Lower Cretaceousin the lower course of Lena. Sci. Rep.,
Inst. Arct. Ceol. Min. Ceol. USSR, Proc.
Palaeo11t. Biostratigr., vol. 3, p. 69-76, pis.
1-2. (in Russian).
- - (1966): Some early Cretaceous plantsfrom the Zyrianka District (Lena CoalBasin). Ibid., vol. 15, p. 49-76, pis. 1-7.
(in Russian).

279- - (1968) : New late Mesozoic ferns from
Yakutia, in 'New genera of ancient plants
and invertebrates in USSR, vol. 2, pt. 1'.

All Union Sci. Rep., Ceol. Ins!., Min. Ceol.
USSR, p. 49-51, pI. 16. (in Russian).
- - & PAVLOV, V. V. (1963): Stratigraphy
and flora from the Cretaceous beds ofLena·Olenek region of Lena Coal-Basin.
II Problems of oil and gas content bedsin Arctica. Bull. Inst. Arct. Ceol., Min.
Ceol. & Protect. Undergr. Res., USSR.
vol. 128, p. 1-96, pis. 1-49. (in Russian).
Y ABE, H. (1903):
Mesozoic plants from
Korea.
journ. Call. Sci., Imp. Univ.
Tokyo, vol. 22, no. 8, p. 1-59, pis. 1-4.
YOKOYA~IA, M. (1889): Jurassic plants from
Kaga, Hida, and Echizen. Ibid., vol. 3,
pt. 1, p. 1-66, pis. 1-14.

Akaiwa iJ.r-;'fi,
Bettokuzure JJIj~ <fh,Fukuirl\l;Jt,
Hakusan BilJ,
Ishikawa EJI!,
Itoshiro :f:ifi&B,
Iwaidani ;fi;Jt:;:t,Izumi-mura 19URtJ.
Kaisekiyama fl-EW,
KamiUchinami J::tr1Bl,
Kiyosue ri~*,
Komatsu 'H".c,
Kuwashima (Kuwajima) *ti&i,
Kuzuryu :fL~J(I'B,
Mochiana :fIf!\:,Nagdong (Naktong) ~*,Oguchi ~ I=l,
Osugidani*t~:;:t,Ozo ~~,Ryoseki 1ifiE,
Shiramine-mura Bm$:H,
Tamodani rnDi::;:t (fEIfrJ:;:t),Tetori (or Tedori) 'fJfJl.

**::z~ 7 :/l::'if!IiJ.r-;fiJl (E~&BJii:tlf.Hff)) 0)11i'!4W1l:E (jj1!!Jn): ~ ~1c:.¥IH!r (KI"IURA &SEKIDO, 1976b) Lt-:~~Ic:.1Jn;t -C, ~1?1c:.---::>~O)~1i.l~ jj1!!JQ~cJiiJi:Lt-:; Cleichenites nip-ponensis, Coniopteris saportana, Adiantopteris sewardii, A. toyoraensis, Cladophlebis
ex gr. williamsonii, Raphaelia diamensis, Dictyozamites cfr. obliquus, Nilssonia
schmidtii, Butefia? sp., Cinkgoites paradiantoides, Arctobaiera? sp., Elatocladus sp.
C U J: u~ sp. D, Protodammara sp. U J: (f Carpolithes sp.
:. h -r:, 1976if.j;J ll1J1c:.vi~ I? h -C l ,t... iJ> "J t-:iJ.r-;fiJl U J: "(fFiiJ;f§~JlO)11i'!4W:tlfO)mJR~~(:!:.~-;zHc:.if-:i" c U ~ c t... "J t:: 0 ~ ~ 1c:.'¥1i15 L t-: Adiantites Ill1. (GOEPPERT, 1836) Ic:.l~~? I) ,*~i1li)( J: ~ Adiantopteris ~ (V ASSILEV5KAJA, 1968) ~ J'Ih' 7.< eeL t-: 0 "i t-: Cleichenites aff. porsildi Ic:.---::>l'-Cfi, 4-JiNH'1!!Il*iJ~t-\tl?h, :'hc~~0)1!!Il*c~il'f.ii'!IH:'lt'R~M L td6*, :. h I? fi, Cleichenites porsildii c !KJJiJ"C'~t... l':' c iJ~ ~Jj~ L t-:O)"C'::: :::IC!I}F.cJlll(;L t-:o tJ.J::O):' -t:" Coniopteris saportana, Raphaelia diamensis, Dictyozamites
cfr. obliquus, Nilssonia schmidt ii, Cinkgoites paradiantoides, Protodammara sp. t... 1:'
fi, l3*iJ>l?li:/&fJJO)ffi!±l-r:.'l?00 :.hl?fH'fh{, VAKHRAMEEV 1c:.J: "J-C~Pl[\~:!l, -Cl'
0, :/:;1. 7 *,ciJ> I? ll1JWl B!!!!*,~Jc:.td-: {,';'-'" ~ 711i'!4WtmJl!!.!K~!\o/.J:tlfI:'fi ~b6b-C1}jjjjiB9;'d:fi,~"C'.'l?00*N te ~ . I*l P fi3 IX

Trans. Proc. Palaeont. Soc. Japan, N. S., No. 109, pp. 280-292, pI. 39, April, 30, 1978

FURTHER NOTES ON VASCOCERATID AMMONITESFROM HOKKAIDO(STUDIES OF THE CRETACEOUS AMMONITES FROMHOKKAIDO AND SAGHALIEN-XXXIII)687.

T A TSURO MATSUMOTO
c/o Department of Geology, Kyushu University, Fukuoka 812

and
KIKUWO MURAMOTO
Mikasa City Museum, Mikasa, Hokkaido 068-22

With Notes on the Early Turonian Palaeogeography(Tatsuro MATSU~IOTO)

Abstract. Since previous descriptions (MATSUMOTO, 1973), more ammonites of
the Vascoceratidae have been obtained from the Cretaceous of Hokkaido. They aredescribed in this paper, in which a new species of Fagesia is included.
In connexion with the distribution of the vascoceratids, notes are given on the
Early Turonian palaeogeography.

stratigraphy and biogeography.
This is a contribution to the international project: Mid-Cretaceous Events.
The work has been financially supportedby the Ministry of Education with theGrant-in-aid No. 154280.
Before going further we thank Dr.
Hitomaro HONDA, Chief Geologist, Mr.
Yasutaka FUJISHIMA, Geologist, and Mr.
Tsutomu SA TO of the Hokkaido Colliery& Steamship Co. Ltd., Yubari, who kindly
provided us interesting specimens for ourstudy; Drs. Hiromichi HIRANO and Kazushige TANABE and Mr. Yuichiro MIYATA(a student) of Kyushu University who
cooperated with us in the field work andprovided the necessary specimens for thisstudy. Dr. K. TANABE and Miss Mutsuko
HAYASHIDA have assisted us in preparing
the figures and the typescript.

Introduction
One of us (MATSUMOTO, 1973) described
three species of the Vascoceratidae fromthe Turonian of Hokkaido, giving a noticeon their palaeobiogeographical implications. They / were Vascoceras sp. aff. V.
duratidi (THOMAS et PERON), Fagesia
thevestensis (PERON) and Fagesia sp. cf.
F. rudra (STOLICZKA). Since then more
examples of the Vascoceratidae from
Hokkaido have been assembled, aided
much by several friends of ours. In thisand another paper (MATSUMOTO, 1977a)these species are described. We now
have six species which afford us a valuable basis to discuss the Turonian bio-

* Received August 26, 1977; read Oct. 4,
1976 at Sapporo.
280

687.

Vascoceratid ammonites from Holclcaido

Systematic Descriptions

Family Vascoceratidae SPATH, 1925
Genus Vascoceras CHOFF AT, 1898
Type-species:- Vascoceras gamai CHOFFAT, 1898.
Remarks: - See MATSUMOTO 1973, p.
27-28.
Vascoceras sp. aff. V. durandi(THOMAS et PERON)
Text·fig. 1
1973. Vascoceras sp. aft. V. durandi, MATSU.
MOTO, Trans. Proc. Palaeont. Soc. Japan,[N. S.], no. 89, p. 29, pI. 8, fig. 1; text.
fig. 1.

Material :-GK. H 5856, from loco R 5235
pI, and GK. H 5857, from loco R 5207 p8,
along the main stream on the River Obira-- " ,......

"-

,
\

\
\

\

\

\
\
\

lOmm

a

_____ 1I
J
I

Text.fig. 1. Vascoceras sp. aft. v. durandi(TI-IOYIAS et PERON). GK. H5856, from loco
R5235p, lower part of unit Mj, Obira district.
Diagrammatic whorl-section (a) and external
suture (b) outside of the umbilical shoulder.
(T. M. delin.)

281[=Opiraushibets] ; ? GK. H 5858, from loco
Y 6017 p5, in a small valley on the rightbank of the creek Taki-no-sawa, Oyubariarea, Hokkaido. All three collected by afield work team of Kyushu University(H. H., K. T. & T. M.)
Descripti ve remarks:- The three specimens of dissimilar size are all incompletely preserved. They are smooth ishand show the globose and considerably
involute shell-form, with inflated flanks
and a rather flattened venter. The sutures have massive broad saddles, an
opened general outline of L, and moderately deep incisions at the base of L.
All of these characters suggest that the
specimens are probably referable to thespecies which was previously describedunder Vascoceras sp. aff. V. durandi(THOMAS et PERON, 1889) (see MA TSUMOTO, 1973, p. 29, pI. 8, fig. 1 ; text-fig. 1).
Occurrence :-Although the three specimens were obtained from fallen or floatedcalcareous nodules, the two localities
R5235p1 in the Obira area and Y6017p5
in the Oyubari district probably indicate
the derivation from a limited stratigraphic position in the lower part of theLower Turonian. The previously reported (MATSUMOTO, 1973) specimen of Vascoceras aff. durandi came in situ fromloco R2513a, but this locality is isolated
and its correlation with the better exposed and more carefully measured
sequence along the main stream of theRiver Obira has yet to be worked out.
For the locations readers may refer tothe route maps in TANABE et a!. (1977)
and also HIRANO et a!. (1977).

Genus Fagesia PERVINQUIERE, 1907
Type-species: - Olcostephanus superstes
KOSSMAT, 1897.
Remarks:-See MATSUMOTO, 1973, p. 32.

Tatsuro MATSUMOTO and Kikuwo MURAMOTO

282

Fagesia spheroidalis PERVINQUIERE
PI. 39, Fig. 1; Text-fig. 21907. Fagesia superstes (KOSSMAT) var. spheroidalis PERVINQUIERE, Etudes de pale.
ontologie tunisienne. 1. Cephalopodes
des Terrains secondaires, p. 32,1, pI. 20,
figs. 3, 4 and fig. A.
1965. Fagesia superstes var. spheroidalis COLLIGNON, Atlas des Fossiles Caracteristiques de Madagascar, fasc. 12, p.46,
pI. 395, fig. 1677.

Lectotype :-Of the two illustrated syntypes the larger one (PERVINQUIERE, 1907,
p. 324, fig. 122, pI. 20, fig. 4 and fig. A)
is designated here as the lectotype of F.

spheroidalis.
iV/aterial:- Yb 3001 of K. MURAMOTO'S
Collection, fro:n a calcareolls nodule resting on the floor of the Taki-no-sawa, immediately west of loco Y5102 of MA TSUMOTO and OKADA (1973), in the Oyubari
district of central Hakkaido.
Specific characters: - Shell large andcadicone, consisting of much depressed
whorls which have a broadly arched venterand much depressed section. Umbilicus
moderately narrow, about one third of
the shell-diameter, deep, and surrounded
by a nearly vertical umbilical wall anda subangular shoulder.
Umbilical nodes thick and blunt, about

10mm

J
/
/

/
',: '\'.. f;\\,tv "'I u, \. '-"/\a...... r;J;;}

5

' ,

( (!

r

1I?tfq L~m it :, '.' "·

b

'l'f

Text·fig. 2. Fagesia spheroidalis PERVINQUIERE. Yb 3001 of K. MURAMOTO Collection,from near loc. Y5102, Oyubari area. Diagrammatic sketch of frontal (a) and lateral (b)views, with a restored shell-form; external suture (c) at the middle growth-stage (whorl. height=43 mm). (T. M. delin.)687.

Vascoceratid ammonites from Hoklcaido

12 to 13 per whorl. They may bestrengthened at the umbilical sh oulder
on the outer whorl. Radial ribs weak,
gently concave and numerous; 4 or 5
ribs corresponding to a node, somebranched from the node and others inserted. On the whorl of the late growthstage the ribs are much weakened or almost lost.
Suture of Fagesia type, being similar
to that of F. superstes as illustrated by
KOSSMAT (1897, pI. 17 [6], fig. lc), having deep E and L, tall saddles at E-L and
L-U2, narrow and long lobules and folioles.

Description of the Oyubari specimen:This is still septate at its diameter of
163 mm, and no body-chamber is preserv-

283

ed. As shown in the measurements below, it is characterized by its cadicone
general shell-form, much depressed whorlsection (B/H=2.46), broadly arched venter, deep umbilicus showing a stepwise
structure due to the combination of asubangular umbilical shoulder and a highand vertical umbilical wall, thick nodes
at the umbilical shoulder numbering 12
or 13 per whorl, and weak ribs branchedat the nodes and also inserted between
them. The ornament becomes blunteras the whorl grows. The suture is fairly
well exposed, showing the general
pattern of Fagesia (see Fig. 2c). L is
expanded by diverging branches.

Measurements (in mm):Specimen

DiameterUmbilicus

HeightBreadthB./H.

Yb 3001
Lectotype

163 (1)135 (1)55 (0.34)
36 (0.27)

58 (0. 36)
53 (0.39)

145 (0. 89)
139 (1. 72)

2.46
2.62

Discussions:- The described specimen
from Hokkaido has essentially the samecharacters as the lectotype and other examples of Fagesia spheroidalis from Tunisia and Madagascar (listed above). Although it shows a somewhat broader
umbilicus and a less depressed whorl,
these minor differences are regarded as
variations within a species, as is somerange in the number of tubercles (10-13
per whorl).
Fagesia spheroidalis was established by
PERVINQUIERE (1907, p. 324) as a varietyof F. superstes (KOSSMAT) (1897). Thishas been followed by COLLIGNON (1965,
p. 46). We think it better to regard themas distinct species, because of the distinct
morphological difference which would be
effective enough for giving rise to adissimilar mode of life. F. spheroidalis
has much broader whorls than F. superstes. In the former the umbilicus showsa step-wise deepening, whilst in the lat-ter it is crater like. These charactersshould be effective to the mode of movement in the sea water. Moreover, theformer has more numerous and finer ribs
than the latter. L in the suture of theformer has larger and. cmore divergedbranches than that of the latter.
Occurrence :-In Tunisia and Madagascar this species is reported to occur inthe Lower Turonian. The locality recordof the Oyubari specimen strongly suggests the derivation from a comparatively
upper part of the Lower Turonian sequence along the Taki-no-sawa.

Fagesia japonica sp. noV.
PI. 39, Figs. 2, 3; Text-fig. 3

Material :-Holotype, HCS. No.1, froma sandy calcareous nodule at loco H2074,
on the left bank of a creek called the
Nutapomanai, a tributary of the River

284

Tatsuro MATSUMOTO and Kiku'Wo MURAMOTO

Hobetsu, collected by Tsutomu SATO
(Sept. 1971). Paratype 1. GK. H5855 fromthe mudstone at loco R5231b, main streamof the Obira [=Opiraushibets], found by
Yuichiro MIYATA during the field workby a team of Kyushu University (K. T ANABE, H. HIRANO, Y. MIYATA and T.
MA TSUMOTO, on Aug. 13, 1975). Paratype 2, Ob1005 of K. MURAMOTO Collection (Mikasa City Museum), from a calcareous nodule at R4601, an intensely
meandering point of the creek of Nakakinembetsu, a tributary of the Obira, at
a point 250 m NWW from the conferencewith a small tributary called the 82 Rinpan-no-sawa, collected by K. MURAMOTO(Sept. 16, 1973).

cSpecific characters:-Shell large andglobose in general aspect. consisting of
fairly involute whorls. which have a steep.
almost vertical, high umbilical wall, subangular umbilical shoulders. gently convex, convergent flanks passing graduallyto a rounded venter, and accordingly asemi-circular to semi-elliptical cross-section, with the maximum breadth between
the umbilical shoulders. Umbilicus fairly
narrow and deep, showing a stepwise
structure by the combination of verticalumbilical walls and subangular shoulders.
Inner whorl has small tubercles at theumbilical shoulder, 10 or so per whorl, andnumerous, weak ribs, which are flex iradiate, diverged or intercalated on the

J

lOmm

Text·fig. 3. Fagesiajaponica MATSU~JOTO et MURAMOTO, sp. nov. Holotype, HCS. No.1
(T. SATO CoIl.), from loco H2074p, Hobetsu district. Diagrammatic sketches of lateral (a)and back (b) views· and a whorl·section (c) ; external suture (d) at S. (T. M. delil1.)

687.

Vascoceratid ammonites from Hokkaido

flanks and curved moderately forward on
the venter, where faint constriction like,slightly deeper inters paces are periodicallydiscernible. Outer whorl nearly smooth,but with distant, blunt umbilical nodes.
Suture essentially similar to that ofFagesia superstes as illustrated by KosSMAT (1897, pI. 17 [6], fig. lc), but has asomewhat broader stem of L and abroader saddle between E and L.
Remarks:-Holotype is immature but
well preserved. Paratype no. 1 (D.=87.5)

285

is somewhat larger than the holotype,but its outer half whorl is poorly preserved and an apparently subtrigonal
whorl-section of the preserved last partmay be due to the secondary deformation.
Para type no. 2 is much larger and regarded as representing the adult stage.
Its last septum is at about 210 mm in diameter but its body-chamber is almost lost.
Its outer whorl tends to be subtrigonalin .cross-section and its height seems to
be reducing.

Measurements (in mm):Specimen
HCS. No.1
GK. H5855
Db 1005

Diameter
57.0 (1)54.5 (1)207.0 (1)Umbilicus
10.5 (0.18)
10. 1 (0. 19)
41. 5 (0.20)

Discussion:- This species is characterized by its peculiar shell-form which recalls
us certain species of Vascoceras [e. g. V.
polygonum BARBER (1957, p. 17, pI. 5, fig.
2; pI. 29, figs. 1-3)], but its suture is distinctly of Fagesia type, characterized bytall saddles deeply incised by narrow
lobules.
In the same respect it resembles Fagesia
involuta BARBER (1957, p. 27, pI. 9, fig. 3 ;pI. 29, figs. 6-7), from the Lower Turonianof north-eastern Nigeria, which was regarded by BARBER as somewhat intermediate between Vascoceras and Fagesia.
That Nigerian species has, however, more
distinctly sub trigonal whorl-section andless numerous,· much coarser umbilicaltubercles.
F. jajJonica is fairly close to Fagesia
rudra (STOLICZKA, 1865), a more wide"spre::).d species known from the Lower
Turonian of southern India (STOLICZKA,
1865, p. 122, pI. 60; KOSSMA T, 1897, p. 29[136J), Tunisia (PERVINQUIERE, 1907, p..
322), Madagascar (COLLIGNON, 1965, p. 48,
pI. 396, fig. 1678A; p. 397, fig. 1678-B),
Spain (WIEDMANN, 1960, p. 720, listed

Height29.0 (0.49)
27.5 (0.50)
41. 5 (0.44)

Breadth
42.4 (0.72)
20 x 2 (0.7)
65 x 2 (0.6)

B./H.
1. 46
1.4
1.4

only) and probably also Hokkaido (MATSUMOTO, 1973, p. 34, text-fig. 3), in its globose aspect, narrow and deep umbilicus
and weak ornament. It is, however, distinguished from that species in its somewhat higher whorl with a distinctly narrower, moderately instead of broadly
rounded venter, and somewhat broader
stem of L.
Some of the variable forms of Fagesia
lenticu~aris FREUND and RAAB (1969, p.
36-42, with subspecific names which weregard as untenable because of their occurrence in the same zone of the samearea), from Zone 6 of the Lower Turonianof Israel, may be similar to F. japonica
in shell-form but has distinctly coarser
ribs on its inner whorl.
Occur-renee :-See ·the locality records
described under the heading Material.
The sandy layer of the type locality inthe sequence of the Nutapomanai is certainly . lower than but not much apartfrom. the prolific Zone of Inoceramus
hobetsensis and accordingly it is regarded
as representing a comparatively upper
part of the Lower Turonian in the Hobe-

286

Tatsnro MATSUMOTO and Kiknwo MURAMOTO

tsu area. The para type no. 1 is precisely
allocated at a horizon immediately below
the key member of tuff and tuffite in the
middle of Member Mj of TANAKA (1963).
This is in the middle part of the Lower
Turonian sequence in the Obira area,
since Vascoceras aff. durandi came fromthe lower part of the sequence along thesame route. The paratype nO. 2 fromthe same Obira area is a somewhat transported calcareous nodule derived probably
from somewhere within Member Mj. Itshould be noted that Neoptychites cephalotus (COURTILLER) was found in anothernodule of the same spot (see MATSUMOTO,
1977a).
Appendix

Notes on the Early Turonian
Palaeogeography(Tatsuro MATSUMOTO)
In connexion with the distributional
records of the vascoceratid ammonites, I
should like to give further remarks on
the palaeobiogeographic aspects of the
Early Turonian time.
En vironmental conditions;- Ammonites
belonging to the Vascoceratidae normallyoccur abundantly in the sediments ofshallow epicontinental seas. They aremostly characterized by a globose orroundish shell-form, smooth ish surface
with reduced ornaments and more or lesspseudoceratitic sutures. Presumably thesemorphological characters of the shell may
have been favourable for their living invery shallow, sometimes wavy seas.
In the Cretaceous rocks of Hokkaido,
vascoceratid ammonites are indeed rare
in comparison with desmoceratids, tetragonitids and certain groups of heteromorpha, but they do occur. Aside fromtwo species of Hourcquia of later ages,

there are now six species of the Vascoceratidae from the Lower Turonian of
Hokkaido. One of them is Vascoceras aff.
durandi, for which four examples are atour disposal and three of them camefrom a limited part of the Obira area.
There are four species of Fagesia, of
which one is, so far, endemic of Japan.
This is represented at present by at least
three specimens.
The occurrence frequency of the above
species in Hokkaido is approximately thesame as that of certain species of the
Acanthoceratidae or Collignoniceratidae
there.
As is described in another paper (MATSUMOTO, 1977a) Neoptychites cephalotus(COURTILLER) has recently been foundfrom the Obira area of Hokkaido. It isrepresented by an adult specimen inwhich the body-chamber is nearly completely preserved.
The above facts altogether suggest thatat least several species of the Vascoceratidae lived in the Turonian Japanese province. Postmortem drifting of shells fora long distance from somewhere in epicontinental areas around the Tethys could
be considered as another alternative, but
this seems to be less probable for theincreasing records of the vascoceratidsfrom our province. The relative scarcityof the fossils is probably due to that themain part of the sedimentary basin of
Hokkaido (i. e. the so-called Yezo geosyncline) was more or less deeper andoff-shore than the original habitats andthat the optimum shallower parts at themargin of the basin may have been narrow because of the tectonic instability inEast Asia. Species of Fagesia havemore complex sutures than other generaof the Vascoceratidae and they may
have an ability to go down to somedeeper part of the sea. This may beconsistent with the fact that fossils of687.

Vascoceratid ammonites f1·om Hokkaido

Fagesia have been found more commonly
in Hokkaido than other genera of thefamily.
Correlation: - Vascoceras and F agesia
occur in the Lower Turonian of various
region of the world and they have beenfound also from the Lower Turonian
equivalent in Hokkaido. Inoceramus (Mytiloides) labiatus (SCHLOTHEIM) (s. 1.) occurs in the same unit, if not in the same
bed (MATSUMOTO and NODA, 1975).
If we examine more carefully the stratigraphic sequences, we notice that fossilsof Fagesia occur in (or presumed to havederived from) comparatively upper to
middle parts of the probable correlativeof Lower Turonian in Hokkaido. For
instance, in the sequence exposed along
the main stream of the Obira, Fagesia
japonica is found at a horizon about 50 m
above that of Vascoceras aff. durandi, although there is still a doubt about theadequate correlation of the bed of thelatter species exposed at loco R2513a on
the bank of the tributary Okufutamatawith that of the main stream. It should
also be noted that a larger example ofF. japonica was collected from the Nakakinembetsu, another tributary of the Obira, from the same spot as a specimen of
Neoptychites cephalotus. Although they
were obtained in transported or washedout nodules, they have the same lithologic
character that suggests the derivationfrom the same unit Mj (see MATSUMOTO,
1977a).
The above facts are generally in harmony with the successions in the Tethys
region, as revealed by WIEDMANN (1960,1964) in Spain and by FREUND and RAAB
(1969) in Israel.
As has been pointed out by HANCOCK
et al. (1977), the adequate scheme of theTuronian biostratigraphic subdivision has
not yet been established even in western
Europe. Although the occurrence is287

rather infrequent, I hope that an increasing number of records of the vascoceratid
ammonites from Hokkaido may serve forthe correlation of the ammonoid faunasof the Tethys region with those of the
Pacific.
Palaeogeographic aspects:- Vascoceratid
ammonites are distributed mainly in theTuronian 'epicontinental sea areas facing
the Tethys Sea and its extensions. On
the previous occasion (MATSUMOTO, 1973)
a Turonian palaeobiogeographic map waspresented, showing the distribution of
selected ammonite genera. That was
drawn on a world map of the present
land and sea configuration.
In this paper I dare to plot the distribution data of Fagesia on a tentatively
reconstructed palaeogeographic map (Fig.
4). For the reconstruction I depend essentially on DIETZ and HOLDEN (1976)rather than SMITH et al. (1973), because
the former seems to be preferable to explain the faunal migration. For the earlyTuronian palaeogeography it is necessary
to modify reasonably the two maps (atabout the beginning and the end of theCretaceous period) of DIETZ and HOLDEN.
One of the questions in the reconstruction is how broad or narrow was the
Tethys Sea in the early Turonian time.
Another question is how broad or narrow
was the opening North and South Atlantic
Oceans. The answers would affect theinterpretation of faunal similarity anddissimilarity between both sides of the
deep sea-ways.
As the Turonian is at the middle ofthe long period of geomagnetic quietness
0. e. a continuously normal geomagnetic
polarity) (LARSON and HELSLEY, 1975), it
is fairly difficult to allocate precisely thesubcontinents of India and Madagascar
on the map. The result would also affectthe interpretation of Turonian faunalaffinities between Japan and these places.

288

TatSt£1'O MATSUMOTO and Kikt£WO lV!URAMOTO

Text-fig. 4. Map showing the distribution of selected genera of the Vascoceratidae:
Vascoceras and/or Plesiovascoceras with solid reversed triangle; Paravascoceras and Paramammites with solid circle; Fagesia with empty triangle. Tentative reconstruction of EadyTuronian palaeogeography modified from DIETZ and HOLDE=" (1970). (T. M. delin.)

In view of these difficulties, the map
in this paper is quite tentative, but I haveshown it towards further refinement in
the future.
Some information of regional geology
should be taken into consideration for thequestions. For instance, the pink pelagic
limestone of the Scaglia rossa of the Italian Appenines record the existence ofdeep sea in Late Cretaceous times up to
middle Eocene (ALVRAFEZ eta!., 1977).
The Aruma pelagic shale, comprising the
Hawasina facies, of the Oman mountains
record the existence of eugosynclinal deepsea in Late Santonian-Early Maestrichtian
times (WILSON, 1969). In Early Turonian,
therefore, the oceanic part of the Tethys
must have existed with a certain breadth.

As to the South Atlantic the present
reconstruction is much broader than thatof REYMENT and T AIT (1972). In viewof the hypothesis of a world-wide increasein spreading rates during the period of
110 to 85 m. y. ago (LARSEN and PITMAN
III, 1972), it is strange to see little opening of the South Atlantic from Middle
Albian to late Early Turonian in theirmap. Moreover, the recent informationof DSDP Leg 40 tells us that the drilling
cores at site 364 contain cosmopolitan
Albian ammonites (Mortoniceras, Puzosia(?), Tetragonites (?) etc.) and Inoceramus
ct. anglicus WOODS (see MATSUMOTO,
1977b, in press) and that the Albian andUpper Cretaceous sediments are micritic
and pelagic. These suggest the exist-

687.

Vascoceratid ammonites 11'0111 Hokkaido

ence of a free sea-way rather than aclosed one in Late Cretaceous times.
The distribution pattern of the vascocera tid fauna in contrast to Collignonieeras(Sel!c),noeeras) assemblage can be explained, even if the South Atlantic was opened
with a moderate breadth. I should consider the two kinds of oceanic currents
or water masses in the oceanic area andfactors of optimum depth in accordancewith the history of transgression-regression in the epicontinental area.
Considering the effect of subsequenterosion, the shelf sea is drawn to be
somewhat broader than the outcropping
area of the Lower Turonian, as in myprevious map. Taking the Turonion regression from the Arabian shelf (POWERS
et aI., 1966; AL NAQUIB, 1967) into consideration, the epicontinental sea is revised
to be reduced, although how narrow was
the shelf sea in the Early Turonian is
not precisely recorded in the availablereferences. The want of information insouthern Asia is the same as in the previous ~ase.
Although I plot the distribution data of
selected five genera, the present map (Fig.
4) is fairly good to understand or interpret the following palaeobiogeographic
features: (1) In general the vascoceratids
were distributed in the Early Turonian
epicontinental areas surrounding the
Tethys sea and its extensions. (2) Vascoeeras and Plesiovaseoeeras prevailed in
the northern shelf sea, whereas Paravascoceras, Gombeoceras and Paramamllzites did so in the southern shelf sea, as
FREUND and RAAB (1969) pointed out.
(3) This faunal distinction was not strict
and the two faunal elements intermingled
to some extent (MATSUMOTO, 1973). (4)The intimate faunal relation between
West Africa and East Brazil may havebeen due to the southern equatorial currents in the South Atlantic Sea. Whether289

the intimate faunal affinity of this region
with the northern Andean province canbe explained in a similar way or otherwise is a problem to be worked out. (5)The distinct fauna of Morocco (COLLIGNON, 1966) may be ascribed to thewelling up of the cooler water mass of
the North Atlantic (EINSELE and WIEDMAl\N, 1975). (6) There was naturally
a faunal affinity between southwestern
Europe and the Gulf Coast plus thesouthern Western Interior of North
America. (7) The vascoceratid fauna ofthe \Vestern Interior had some, if not
remarkable, peculiarity (e. g. prevalenceof the subgenus Greenhornoeeras COBBAN
and SCOTT, 1972) as that of central Asia
had another peculiarity. (8) Fagesia andN eoptyehites (see also another map in
MA TSUMOTO, 1977a, fig. 2). of the late
Early Turonian, are more widespreadthan other vascoceratids. This is probably due to more active ability of theirlocomotion and also to expanded marinetransgression in many regions. (9) There
are doubtful records of Fagesia from New
Caledonia (KILIAN, 1910) and California(represented by F. siskiyouensis ANDERSON, 1931), for which no suture has been
described and the homoeomorphy withcertain Lewesiceras could be considered.
Aside from the above doubtful one, there
is in California a species of Plesiovascoeeras which is somewhat allied to theWestern Interior species (see MATSUMOTO,
1959, p. 102). (10) It is considered thatcertain species of the Vascoceratidae lived
in the Japanese province (see p. 286).
Hokkaido is much separated from any of
the known distributional areas of thevascoceratids. To make clear the routeof migration the information from southern Asia is especially wanted.

290

Tatsuro MATSUMOTO and Kikuwo MURAMOTO
References Cited(References of the basic data for the distribution map of the vascoceratids were indicated in MATSUMOTO, 1973 and not repeated here, but for the addition of FRITZSCHE, 1924.)
AL NAQUIB, K. M. (1967): Geology of the
Arabian Peninsula. Southwestern Iraq.
U. S. Ceol. Surv. Prof. Paper 560-G, p.
1-5c1, pIs. 1-4.
ALVAREZ, W., ARTHUR, M. A., FISCHER, A.G.,
LOWRIE, W., NAPOLEON, G., SILVA, 1. P.
and ROGGENTHEN, W. M. (1977): Upper
Cretaceous-Paleocene magnetic stratigraphy at Gabbio, Italy. V. Type section for
the Late Cretaceous-Paleocene geomagnetic reversal time scale. Ceol. Soc. Amer.
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A:"DERSO:", F. M. (1931): The genus Fagesia
in the Upper Cretaceous of the Pacificcoast. Jour. Paleont., vol. 5, no. 2, p. 121126, pIs. 15-17.
BARBER, W. (1957) : Lower Turonian ammonites from north-eastern Nigeria. Ceol.
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COBBAN, W. A. and SCOTT, G. (1972): Stratigraphy and ammonite fauna of the Graneros Shale and Greenhorn Limestone near
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COLLIGNON, Maurice (1965): Atlas des Fossiles
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EINSELE, G. and WIED'I;IANN, J. (1975) : Faunaland sedimentological evidence for upwelling in the Upper Cretaceous coastal basinof Tarfaya, Morocco.
I Xth Intern.
Congr. Sedimentology, Nice, 1975, Theme1, p. 67-74.
FREUND, R. and RAAB, M. (1969) : Lower Turonian ammonites from Israel. Spec. Pap.
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HANCOCK, ]. M., KENNEDY, W. J. and WRIGHT,
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K. (1977) : Mid-Cretaceous biostratigraphic
succession in the Oyubari area, central
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KILIAN, W. (1910) : Sur la presence de Fagesia
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Explanation of Plate 39
Fig. 1.

Fagesia spheroidalis PERVINQUIERE· ........................................... Page 282
Yb 3001 of K. MURAMOTO'S Collection, from Taki-no.sawa, Oyubari area, central Hokkaido. Lateral (a) and frontal (b) views, xO.5
Figs. 2, 3. Fagesia japonica sp. nov.··················· ....... · ....................... Page 283
2, Obl005 of K. MURAMOTO'S Collection, from loc. R4601p, Naka-kinembetsu in the Obiraarea, northwestern Hokkaido. Lateral (a) and frontal (b) views of a larger paratype,xO.3.
3, Holotype, HCS. No.1, from loco H2074, Nutapomanai, in the Hobetsu area, central
Hokkaido. Lateral (a) and back (b) views, xl.
Kyushu University [K. TANABE] photos, without whitening.

687.

Vascocemtid ammonites from Hokkaido

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TANABE, K., MATSUMOTO, T., HIRANO, H.
and MIY ATA, Y. (1977): Stratigraphy of
the Upper Cretaceous deposits in the Obiraarea, northwestern Hokkaido. Sci. Rept.
Dept. Geol., Kyushu Univ., vol. 12, no. 3,
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de l'Espagne et du Portugal et s~s cephalopodes. 84° Congres Soc. sat'anles, 1959,
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- - (1964) : Le cretace superieur de I'Espagne
et du Portugal et ses cephalopodes.
Esludios Geolog icos, Insl. Lucas M allada,
C.S.1.C. (Espana), vol. 20, p. 107-148.
WILSON, H. H. (1969): Late Cretaceous eugeo·
synclinal sedimentation, gravity tectonics
and ophiolite emplacement in Oman mountains, southeast Arabia. Amer. Assoc.
Petrol. Geol., Bull., vol. 53, p. 626-671.

82 Rinpan-no-sawa. (82 1*.FlEJ»)R) ,Hobetsu ('f!!.\lJlj) ,Naka-kinembetsu (q:r*'c;ftlJU),
Nutapomanai (;;<;ll ;i'h' j-·n,
Obira (/j>3F) ,[=Opiraushibets (;t 1::,0'7 :/'''' ' / ) ] ,Okufutamata(~=m,t),Oyubari (:;k ,9,*),
Taki·no·sawa (itO))R)292

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01978i'fJ.t~~~OO)c.it,

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Balanoidea" (¥li15-. iiG*107-\}, 108%) t;::tl'ilJ-~ht.:.
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S*ii'!t¥J~~1978i'f~~' i'f~lt1978ip 1 J:j20S (~). 21S (±) 1;::Jii:m*~I;::;t.o~'-C rml*~ht.: ($:1m~ 12215)0

Mid Cretaceous Events lirJ North American Paleontological convension 0) 7J :/-\f A~~ •...•.. -................................................................................... '~lIllltJ't
Pander Society ~;::t±l1lW L -C ........................................................ , .... "J'i1ll.re!i:~
1fffl:ii'!E¥J~a-'*"L' c L~t!t:WO)7iJf:1EilJItiJ· ............................................. , ..... mDi'ffiiE~1O@] IN QUA *~t;::t±lflit L -C .......................................................... rlJJJj( ~~ 4 @]@1~::":/ ]-. '7:t' '/:/;f.;:; '7 A· . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ',*,lR.~:=.

294~

1.lIJ ~~

B;.jq:.;t.;\-t 7.> illl':f'fEjlJ!lt~O)Jeji· ................................................... , ... J1[ r..9 Ihf :Jc
OOA~;~-gil Mt1::.' A r :/::1 7 *O)~fl::;o· ................................................. g§;fj lIB· g§;fjI!JFf-1 :/ r·~M7K*0)~iIii~0)~ji[7Hjlt:.'?\"-C·············""""""" ·~IEJllr.- .!MJ;fj ~. 1JniiUit!!flA few species of Hystrichokolpoma (Dinophyceae) from the Pleistocene sediment in Okinawa
Jima ........................................................................ MATSUOKA, K.
fjg~~~i*I:l:~tt~tJe!G-O)~{I::;o~(ft~EB~W'" ·iitill~1IB . 'NR~.

*" ;a-.

*~Ii£5(fl'!~' iii JlIj!fE• • 'j'JR ~iM5iijlO)tt~jli**~~t:.'?\"-C············· ....... ,.............................. jliijlifji~ti1a~O)tt~~~f:',?\,'-C ............................................................. "j' 7'R~

Fossil Cervidae from Taiwan····································· ·OTUKA, H. and SHIKAMA, T.
On some new materials of Gomphotherium annectens (MATUMOTO) from the Miocene Mizunami
Group····················································································· .
........ KAJ-IEI, T., Okazaki, Y. NONOGAKI, I., and Paleontology Club, Aichi Gakuin Univ.
On Hipparion fauna of the Marageh district, North-West Iran························· ........ .
.................................................... KAMEl, T., ISHIDA, S. and NAKAYA, H.
Eocene land turtle discovered from Yubari city, Hokkaido ....................... ·OKAZAKI, Y.
New species of trionychid turtle from the Pliocene Age Group··················· ·OKAZAKI, Y.
!G-;P9jHt!G-;oW(!G-*t:.AMEBm~~jl1pj<-t 7.> ............................................. ·!MJ;fj:/ltzl!tJ~tM~~!Ji.~1.J>I?Je~(HttdxliX.'F,{I::;ot:.'?\"-C··············· .. ········· ................ :/It 1ElJ:-

Bolivina robusta BRADY t:.~I?;hol'&O)MtmEB*t!&t:.'?\,'-C ........................... ·~t.m.

~mJII:Itl!.1.n:.~I?;hom~=:*c . ~gg*c~w.#JlIO)f1.JbfM:~:}L.'F,~O)1C~············· ·~*JlT . ± ~!MJilI9~*H;oW(!G-t:.'@:-tO;o~*C0)7;;( ~ :rM .. · ........................................ ·ft;: IE ~ fjf~J!t[!JjHi!ffmf!l!!MJIHT1.J>I?Je~ l...t.: Triticites {I::;o~t:.'?\"-C .............................. f& iii j;JJ iJIJ;

Paleontological study on the Copacabana Group at Hill of Jacha Khatawi in Yaurichambi area,
Bolivia, South America, Part 1. Fusulinids········· 'YAl\IAGIWA, N. and URDININAE, M. R.
Biostratigraphical zonation and Fusuline fauna of the Khao Khao section, Sara Buri, Central
Thailand················································· ·TORIYAMA, R. and KANMARA, K.
Cyclina sinensis O)?E9I.~ffiO)1t'l-ij--1 ;;(7f;(jlc-tO)MIll1:~~ .............................
ill IE-·r

H1V~.MO)?E9I.-ij--1 ;;(7f;(jlmlll1:t:,~x.oP1~l:i-v

r:IJ ~ O)-ij-.-( ;;(~tRM:tU: OllI;~l''''''''''''''r ill IE-

Umboniulll miyagiense NOMURA and ONISI, 1940 t:.'?\',-C .......................... "'j' 1R ~ 1:.
*mtltO) Geloina ~~t:.'?\"-C .............................................. !M!JII i.$::: . g§JII !JJg§mB*1:i!Ill~r~*t:'~I?;ho Inoceramus (Cataceramus) ex gr. balticus O)Mtm1Cfl::· .... ·ff IE Jl z
*C~~~mi!llO)~=:*C9I.M{I::1j············· ................................ ···~IE~-l'!~· ~iii~l'!pOccurrence of the Wuchiapingian (Early Lopingian) bivalves from the Nesen Formation in thecentral Alborz Range, Iran················································· ·NAKAZAWA, K.
Shallow sea molluscan fauna in the northern border of the Shimanto Terrain, Kii Peninsula,West Japan··································· ·NAKAZAWA, K., KUMON, F. and KIMURA, K.
Rates and pattern of size change in evolution ...................................... HAYAMI, I.
A systematic survey of the Paleozoic and Mesozoic Gastropoda from Japan··· ................ .
.................................................................. HAYAMI, I. and KASE, T.
=- "" - :IJ v r =- 7fJili(l\7'!-~t:.;t.;\-t 0**""':J ry .l..:!l'-( O)ffIi~ .................... "~IE~± . =:1: jjt
Biometric characteristics of Nautilus macromphalus.· .......... · ...... HIRANO, H. and OBATA, I.
Some early Permian ammonoids from the Taishaku district, Hiroshima Prefecture, Japan····· .
.... .......................................... NISIIIDA, T., HAMADA, T. and NISHIKAWA, I.
Upper Triassic ammonoids from Eastern Timor········· ............................ ·BANDO, Y.
ffJ'.l!Tltri¥:=:ii:*c7 :/"E':r-1 r "Ptychites" t:.'?\',-C ...................................... ;0 ~ ~Mammites and allied ammonites from the Cretaceous of Hokkaido and Saghalien ............. .

*295••..............•..••.••..............

MATSU~\'IOTO,

T., KA\\-ASI-IITA, Y. and FUJISI-IC\IA, Y.

-=- 7 :/lOm:nll¥~lOt-lfti:' ......... , ... #MI-fiZ . 'HjHIllj:: . =J:3&~
Carboniferous brachiopods from Kawai, Hiroshima Prefecture, Southwest japan .. Y ANAGJDA, J.
Elikah~:fr (17:/) IOJ::tf1I.rZ,v.b,>* Nesen ~9=t~c~;t.h0JIiii}.t~~lOfJ~jf\:; ......................... .
. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. ... '1:'J'HJt=· m**rinl; . GOLSIIAC\:I, F.
Urushteni(J from the Permian of Eurasia· ...................................... ·NAKAMUI~A, K.
On some specific aspects of the r,"production of marine ostracods· .. ·IKEY A, N. and OIIISlll, M.
~tifjj:@:7J"j':.l1!!.~J:ifI\ tlijt~*7-;L -pllliJ¥HI ::$:mj::f\lOiIiJ\1f;(\l~1tT:ir.1'tI~· ........................................... *~.}II i¥= . Vli::$:W:rr~t:7L'I'I'lm 'J';f1' ffiC ailli*,c 10 iJk*fi.!J;I'i1tT:i· ................................................... J: !Jlf tl!i ~t
Computer file system of Japanese Cladophlebis················· ·OGAWA, N. and NISIllII'AKI, N.
Ii! JJ Y;1.~ifJ;1~11t£1O Dictyophyllu11l nathorsti ZEILLER IC":) l' -C .......................... rAJiili§i1Ji\;tnr,=FJ&tftjj(H?o1lf~ Adiantites lJaY Ginkgoites K ,,:)l'-C· .................................. '1'~ I~
JoB'll~~~c J: 07J ::--TJil. (Acer L.) 7Hl'ilOfI}~iM c -tlOiiHt*aft ............................. ·#DJ )1: fit *v.
Some coniferous remains from the Palaeogene Noda Group, Iwate Prefecture, Japan. (Part 3).............................................................. KI~IURA, T. and HORIUCHI, J.

*=:m:t'R,~:fITiHc7t;(P-to fFJ9(!li'l 1O::(::jJJHt U-::t-t1tIl IOMHliic ,,:)l ,-c ....... 'lljWH4!~ . jIf;Jlllii1f~ . ,f1l!JfB$ffJ

Jlf*1m:n. R r!flllY,t%) ~!:Ir1~ciW-t 01;f{tIl IO*,Ui~~c ":)l' -C ................. 'IUIIr{;j-M!~ . 1M] FRir'L1: ' ,f1l!JFR$PJ

UJ D~Z.~: Taxonomic studies on some fossil and recent Japanese Balanoidea. Trans. Proc.
Palaeont. Soc. Japan, N.S. No. 107, pp. 136-160, pis. 19-22, 1977; No. 108, pp. 161-201, pis. 2327, 1977.

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11F.1!lF;1l':t/iJVJ!j&;-illl::z. f;L -C {, !u:{flO (j'~Wlr-¥rtT11O /.1=.ffl.!'!91lWi~~~-'t" J1l!JlI!(I(J';t;{jllcit1;..-jl 'k fi-'t"i!P.fi 10 ftlf1Elt t-= rm
ftfl ~.hk'ib' I) -C-;/J) 0:;fi:ilifU::l(ltEl::$:i£{tli :to J: O~JJ~~EIO Balanus amphitrite f!l1llf, B. rostratus, Solidbalanus hesperius,
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Transactions and Proceedings of the PalaeontologicalSociety of Japan

April 30, 1978

New Series No. 109

CONTENTS
TRANSACTIONS
684. KOBAYASHI, Teiichi: Discoactinoceras and the Discoactinoceratidae, fam.
nov....... .... ..... . . . . . . . . . .. .. . . . . .. ... . ...... .... .. . . .. ..... . .. . ... 223
685. HIRANO, Hiromichi: Phenotypic substitution of Gaudryceras (A Cretaceousammonite) . ... ..... . ............. . . . . .. .. . . .. .. . .. . .... . .. ... . . . . ... . . 235
686. KIMURA, Tatsuaki and SEKIDO, Sinji: Addition to the Mesozoic plants fromthe Akaiwa Formation (Upper Neocomian), the Itoshiro Group, Central
Honshu, Inner Zone of Japan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 259
667. MATSUMOTO, Tatsuro and MURAMOTO, Kikuwo: Further notes on Vascoceratid ammonites from Hokkaido (Studies of the Cretaceous ammonites
from Hokkaido and Saghalien-XXXIII) . . ... . ... .. . ... .... .. .. .. . . . . . .. 280
PROCEEDINGS . ..... .. . ... . . . . .. ... .. .. . . ..... .. ... ...... . . . ... . . . ...... ... . . . 293