ISSN 0031-0204

Transactions and Proceedingsof thePalaeontological Society of Japan
New SeriesNo. 131

Palaeontological Society of Japan
September 30, 1983

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Itaru HAYAMI and Ikuwo OBATA

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Trans. Proc. Palaeont. Soc. Japan, N. S., No. 131, pp. 125-134, September 30, 1983

A STORY OF THE BELEMNITE - AN APPROACH BASED ON THE
METHOD OF INVENTING AUXILIARY ASSUMPTIONS IN PALEONTOLOGY(Presidential address, Palaeontological Society of Japan, 1983)

TETSURO HANAI
Geological Institute, University of Tokyo, Tokyo 113
In the last presidential address (Hanai, 1982),
I made an attempt to offer an explanation forthe biological meaning of the furrow observed in
the venter of the belemnite rostrum. This time I
would like to present full particulars of my study
on belemnites with numerous small pits, which
occur in Cretaceous deposits of the Miyako
district, Iwate Prefecture, with special reference
to the bearing that these pits have on the
belemnites.
Frankly speaking, when I described Neohibolites miyakoensis in 1953, I did not pay
much attention to these imperfect belemnites
spoiled with small pits. In fact, it was not before
reading a paper by Seilacher (1968, p. 279-285)
on swimming habits of the belemnites recordedby boring barnacles of the order Acrothoracica,that I first took an interest in Neohibolites withsmall pits. He distinguished two kinds of disposition of borings that differed in distribution andorientation. Borings of one kind are usually
patchy in distribution and in general do not show
any preferred orientation. The other kind of
borings are even in distribution covering theentire rostral surface and show preferred orientation nearly parallel to the rostral axis but inclined on either side of the rostrum towards theposteroventral direction.
In order to explain the regularity in the disposition of the borings of the latter type,

Seilacher invoked knowledge of the fact that
modem barnacles tend to align their cirral nets
towards the water current to feed. He pursued
his argument quite logically, following theprocedure of his "experimental paleontology",
an approach that is actually "the method of
hypothesis" i.e. "by inventing hypothesis astentative answers to a problem under study andthen subjecting these to empirical test" (Hempel,
1966, p. 17). If the hypothesis that the borings
were produced after the death of the belemnites
when they came to rest on the sediments, andthe auxiliary assumption that the barnacles tend
to orient towards the water current are true, thenthese borings must be patchy and inconstant intheir orientation owing to the restriction of the
exposed section of the rostral surface and to therandom direction of the current at the place
where the belemnites came to rest. Contrary to
expectation, observation shows that the borings
are evenly distributed and have preferred orientation. Therefore, either the hypothesis or theauxiliary assumption must be false. However,
the observation of modem barnacles shows theauxiliary assumption to be true, thus the hypothesis must be false. This reasoning takes theform of modus tollens, and if all the premisses
are true, the conclusion must be deductively
valid. Thus he concluded that these borings
are not post-mortal, and therefore pre-mortal,
and that the barnacles aligned themselves with
their cirral net facing towards the current, while
the belemnites were keeping their horizontal
posture and swimming. Further, the preferred* This is the English translation of the presidential address delivered at the Annual Meeting of the Society, held at University of Tokyo,
Tokyo, on 22 January, 1983.
125

126

Tetsuro HANAI

orientation may have been modified slightly
by the effects of gravity. However, what is
actually rejected is the hypothesis that theborings were produced when the belemnites
came to rest on the sediment, and so it is stillquite possible that the borings are post-mortal.
Provided that the borings are pre-mortal,
what phenomena should be observed on the
rostrum? The question is, what is the thicknessof the mantle which secretes the rostral layers?
Seilacher argued as follows. If the hypothesisthat the rostrum was covered by mantle when it
was bored by Acrothoracican larvae, and theauxiliary assumption that the mantle will interfere with the commensal living of Acrothoracicaon the belemnites are both true, then pathologic
irregularities, e.g. irregular growth of rostral
layers, that results in swellings or hardenings
will occur around the openings of the borings toattest to the presence of the mantle. This test
implication is not supported by the observed
evidence, and further each boring preserves its
complete form with a narrow and slit-like opening as can be seen in solid shell surfaces exposedon the present day sea floor. The reasoning ispresented again in the form of modus tollens,and is deductively valid. Thus the rostrum was
not always covered by mantle, and therefore
was exposed in the observed cases, or if it wascovered, the thickness of the mantle was insignificant being "a fraction of millimeter"(Seilacher, 1968, p. 282). Further, because
the rostrum will not grow without a coveringof mantle epitherium, unco-o-ering of rostrum
had to have happened in the last stages of rostral
growth.
Reasoning from the pre-mortal interpretationof the borings and assuming an exposed rostrum
in the adult stage, Seilacher extended his ideas
further into an inquiry into the swimming direction of the belemnites. He asserted, basedon the orientation of the borings, that head-on
movement of the belemnites occurred in the
opposite direction to the direction of streamlining of the rostrum.
His reasoning seems to have gone throughthe following steps: If the belemnites swam

towards the posterior direction as is suggestedby their streamlined shape when they were
infested by Acrothoracica, and if the orientationof Acrothoracica is adjusted with their cirral
nets facing towards the direction of the current,
then the Acrothoracica must have strongly
preferred orientation nearly parallel to therostral axis with the anterior end of the aperture
pointing towards the apex of the rostrum, sothat the Acrothoracica face with their cirral nets
towards the current streaming from the apex of
the rostrum. The observed evidence proved thatthe borings were aligned in the opposite direction
to that predicted above. Therefore, the hypothesis of backward swimming was falsified and as
far as the observed samples were concerned thebelemnites swam in the anterior direction. This
reasoning is again referable to modus tollens andis deductively valid, if all the premisses are true.
Refutation of the auxiliary assumption about
the orientation of Acrothoracica was presented
by Cirripedia specialist Petriconi (1971, p. 137146). He traced the same logic as Seilacher
employed for reasoning that the borings werepre-mortal and the rostrum was uncovered in
the adult stage of the belemnite. But as to theswimming direction of belemnites, he presented
a diametrically opposed conclusion. He noticed
that Seilacher's auxiliary assumption on theorientation of Acrothoracica is not consistent
with present knowledge on modem Acrothoracica and other barnacles. When the cypris
larva of barnacles attaches to the hard surfaceof the substrate by its first antennae, orientation'of the final attachment of cypris larva will
determine the orientation of the borings. Attachment of cypris larva is accompanied by weaknegative rheotaxy. Then, during their metamorphosis after fixation, cypris larva of barnacles
stands on the first antennae, Le. on the attachedpoint, so that the cirral net will face towards thewater current. In the metamorphosis of Acrothoracica, however, the cypris larva turns its
body round 180 degrees twisting its first antennae
in order to bore the hard substrate scrappingwith its dorsal surface. Therefore, the borings
will align so as to have the back of the cirral net

A Story of the Belemnite

127

@
r.

.....

.

ne-..... '.. :::....:. '.' .....: ~:.' ': ... '.
.

.

·'·.Y\ ...' ..... ,:~-----n;!-e-,;......·.. ·0

A

B

c

Text-fig. 1. The relation between the orientation of attachment of cypris larvae and theorientation of adult barnacles. A. Trypetesa sp. B. Lepas sp. C. Balanus sp. based on Turquier(1971); Colman (1909); Crisp and Stubbings (1957), respectively. a, antennular sucker; c, carina;ce, compound eye; ne, naupliar eye; s, scutum; tl, thoracic legs; v, valve of cypris larva or valve
rudiments.
to the water current (Text-figure 1).
• There was no room left for doubt that the
cypris larva attached to the rostrum of thebelemnites so as to point with its posterior end
towards the apex of the rostrum. Such being
the case, the inferred direction of water current
indicates backward movement of the belemnites.
Thus Petriconi (1971, p. 143-146) concluded
that the belemnites generally swam by means ofa rocket principle as is suggested by their streamlined shape. At the same time, however, hisreasons led to the inference that Acrothoracica
had the back of their cirral nets toward the
direction from which the water current presumably was coming. Though the direction of
their cirral nets faces in the reverse direction,
this seeming contradiction no more impedes
his reasoning, for his observations on the behavior of modern Acrothoracica revealed thatthey are able to twist their cirral nets 180 degrees
to face towards any direction of current from

wherever it comes. Further, another group ofboring barnacle species without distint cirral nets
pump water into the mantle cavity with the aidof expansion and contraction of the muscular
mantle sack. So if this type of barnacles wereattached to the belemnite, the direction of theircirral nets is no longer relevant to that of the foodsupply. For details of behavior of boring barnacles refer to the observations of Tomlinson(1955, p. 112). In conclusion, the belemnites
were set forward by Seilacher and backward by
Petriconi, and seem finally to have been driven
into a tight comer.
Things seem to go quite well in this world.
HOlder (1973, p. 60-62) found scars on the
rostrum of a Jurassic belemnite Passaloteuthis
from Germany which are interpreted as thetraces of pointed teeth left on the rostrum by afish of prey when the belemnite moved to makea quick escape from the mouth of the predator.
Scars suggested the ability of belemnites to128

Tetsuro HANAI

move forward and backward and, in case theyneed, to change direction promptly. Jordan,
Scheuermann and Spaeth (1975, p. 334-338)
found bilaterally symmetrical color patterns on
the dorsal and lateral surface of the adult rostrum of Jurassic belemnites, belonging to thegenus Megateuthis from Germany. Borings offungi or algae were also found on the dorsal
patterned area of the rostrum. Thus they inferred
that, in this genus, the rostrum was covered by athin and translucent epitherium or even uncovered in the adult stage.
A few years prior to the publication of these
papers, I noticed while beachcombing that driftwood and other flotsam including the cuttleboneof Sepia when washed ashore are quite commonly infested by barnacles. This experience mademe hit upon a hypothesis that the belemnites,
whose soft bodies were completely removed by
rapid decay shortly after death, might be suspended perpendicularly in the water by buoyancy of air in the phragmocone, like a slender
quill with the rostrum as a sinker. And thebelemnites might be infested with the Acrothoracica during this period of flotation orsuspension. I became satisfied with this inference, because all the observed facts on the borings of the belemnites seemed to be explainablewith this hypothesis. Thus I read a paper on thishypothesis at the regular meeting of the Society
in 1973 (Hanai, 1974, p. 235; 1975, p. 1). At
this point of time, Seilacher's logical sequence ofarguments starting from pre-mortal borings on
the rostrum, passing through uncovered rostrum,and ending with the swimming direction of thebelemnites were broken up in my notion into
three independent statements. In other words,
if my hypothesis holds, no matter whether the
belemnites exposed their rostrum in the adultstage or not, and swam forward or backward,
infestation of Acrothoracica will result in borings
with uniform distribution and preferred orientation on the rostrum of the belemnites.
Once a hypothesis is devised and proposed,a test implication inferred from the hypothesismust be checked by observation and experiment.
The setting behavior of cypris larvae when they
attach to the solid substrate provides a basis forsuch a test. Fortunately, research on the foulingof ships by barnacles provides us with the resultsof many excellent studies. Nauplius larvae ofmost barnacles are known to be dispersed during
their planktonic life. Cypris larvae, however,
have the ability to swim and look about for asolid surface suitable for attachment. This searching behavior leads to the gregarious occurrenceof cypris larvae (Knight-Jones, 1953, p. 595;
Knight-Jones and Crisp, 1953, p. 1110; Crisp
and Knight-Jones, 1954, p. 361). After attachment, they walk about on the surface exploring,recognize their own species, and finally settle so
as to maintain a certain distance from earlier
settlers (Crisp, 1961, p. 435-437). As a resultof a combination of this gregarious and territorial
behavior, the distribution of barnacles on aneven surface is expected to be not random, but
at least, to some extent, uniform within the areaof barnacle infestation, and this will also be moretrue on the evenly cylindrical surface of a vertically oriented belemnite rostrum. Borings on the
rostrum of Neohibolites from Miyako show uniform distribution giving a value of 0.34 for thevariance to mean ratio (S2/X), much less than 1,
which was calculated by dividing the distribution
area of 89 borings into a lattice of 5 x 5 quadrats(Text-figure 2)_
Cypris larvae show negative rheotaxy, orientating with their posterior end upstream (Crisp,
1955, p. 589). But the orientation in the current
is so weak that it occurs only in the absence ofother stimuli, or in most cases its influence is notappreciable at all. Experiments on modem barnacles revealed that the attachment of cypris
larvae occurs under the stimUlation of gentle
water movement. If the current flows rapidly,
then the cypris larvae will fail to attach, or evendetach from the substratum, but once fixed, rapid
flow can not detach them (Walton Smith, 1946,
p. 69). It is, however, not unlikely that the
belemnites could swim very fast so as to escapefrom unpleasant surroundings before cypris
larvae become fIXed. After fIXation and metamorphosis of the cypris larvae, rotation of theshell during growth occurs at the stage of young
barnacles, in order to orient the cirral net towards the current (Crisp, 1953, p. 342; 1955, p.

A Story of the Belemnite

129

ant.

5

6

3

2

1

4

4

3

4

3

3

3

4

5

5

6

3

3

3

4

2

4

3

3

3

post.

A

B

c

Text-fig. 2. Uniform distribution of boring barnacles on Neohibolites miyakoensis. A . a
specimen from the upper horizon of the Tanohata Formation, 8 m below its top, from the northern
cliff of Haipe, Tanohata-mura, Shimohei-gun, Iwate Prefecture, on which the testing of uniformityof distribution is based (x 1.6). B. distribution of points of attachment of cypris larvae . Scattereddots represent the points of attachment of the first antennae of cypris larvae, i.e. the anterior
end of the slit-like opening. C. number of dots in each quadrat of the 5 x 5 grid.

589; Crisp and Stubbings, 1957, p. 189-193).
This is the reason why certain kinds of barnacles
orient toward the current (Crisp and Stubbings,
1953, p. 185). But in the case of the Acrothoracica, rotation can not occur after fixation,and therefore, the orientation of the borings isdetermined by the orientation of the cypris
larvae at the time of fixation (Codez and SaintSeine, 1957, p. 713; Petriconi, 1971, p. 133,
145). In spite of only weak negative rheotaxy,
borings on the rostrum show, strangely enough,strongly preferred orientation.
The cypris larvae just before fixation orient
towards the light and against gravity, and thedominant importance of light and gravity overcurrents in taxis has been well establishedthrough many observations on modem cypris
larvae (Hiro, 1939, p. 594; Crisp and Barnes,
1954, p. 145-149; Uchinomi, 1955, p. 128;
Crisp, 1955, p. 586; Crisp and Stubbings, 1957,
p. 186-188). Therefore, if the hypothesis of
post-mortal flotation of the belemnites is true,
and the infestation occurred during the floating
period with the belemnites keeping their vertical
position, then it is quite likely that strong posi-tive phototaxy and negative geotaxy combined
together might produce strongly preferred orientation of cypris larvae in a vertical direction with
their anterior ends upwards. To be exact, however, the rostrum will float with its axis of elongation not vertical, but slightly inclined in theplane of bilateral symmetry of the rostrum. This
inclination of the rostral axis from a vertical line
connecting the center of gravity with that ofbuoyancy, might produce slight and bilaterally
symmetrical deviation of the orientation of borings from the axis of the rostrum. The inclination
would certainly be distinct in the case of Duvalia
whose rostrum swells in its ventral half. These
test implications seem to be supported by observation (cf. Seilacher, 1968, p. 281; Seilacher andWiesenauer, 1978, p. 148). The pro-ostracum
which would have an appreciable influence on the
floating posture of the belemnite seems to be
extremely susceptible to destruction by wave
action, as is suggested by its exceedingly rareoccurrence relative to that of the phragmocone(Hewitt and Pinkney, 1982, p. 144) and thus it isunlikely to be a factor influencing floating
posture of the belemnite.

130

Tetsuro HANAI

Another question weighing on my mind is
how to explain the fact that borings with preferred orientation have been found so far only on
adult rostra. In this regard, it may be significant
that "fresh" cuttlebones still covered with anextremely thin layer of sticky decaying organic
matter that are commonly found drifting along
the coast of the Inland Sea of Japan during the
spawning season are mostly adult forms. Neohibolites have been found commonly in various
facies of marine sediments of the Miyako
Cretaceous. However, those infested by boringbarnacles occur, with the exception of one
sporadic occurrence in an open sea sandstone,
exclusively in back reef silty sandstones. Thissuggests that the belemnites were infested
in a relatively calm, shallow and more orless closed embayment near their spawning
ground, where cypris larvae might have occurred
gregariously. All of the infested belemnites seemto be adult forms having a very narrow range ofmaximum diameter from 8.82 to 8.95 mm.
The reasoning employed by Seilacher (1968,
p. 282) to support the hypothesis of exposed
rostrum in the adult stage of the living belemnites can also be applied to the post-mortal floating hypothesis because the soft parts of thebelemnites would be removed by rapid decay
shortly after death. The evidence to be expected
and found includes absence of pathologic traces
around the borings, and preservation of the complete form of the boring with its slit-like opening.
As has been discussed in the foregoing paragraphs, there are two conflicting hypotheses
concerning the condition of belemnites at thetime of Acrothoracica infestation: One is the
pre-mortal swimming hypothesis in which therostrum must be covered at least proximally bymantle epitherium, and the other is the postmortal floating hypothesis in which the rostrum
must be uncovered because the soft body wasremoved by rapid decay. If the pre-mortal swimming hypothesis is true, then Acrothoracica
should avoid attaching to any area of the rostral
surface covered with mantle epitherium ofappreciable thickness. Such an area is quite likely
to be found in the anterior proximal section of

the rostrum and in a surface along the lateralfurrows, because the furrows may be interpreted
as scars of the posterior extension of the lateraldevelopment of the mantle epitherium to improve locomotion. Further, certain evidence
seems to support the presence of a soft part
covering the entire rostrum at least in certain
groups of belemnites. In these cases, no room isleft on the rostrum for Acrothoracica to attach.
Classical literature has already shown many longitudinally polished sections of deformed rostra inwhich newly formed rostral layers enveloped andset broken young rostra (Naef, 1922, p. 223;
Kabanov, 1967, p. 62). The new finding ofloosely linked fragments of proximal sections of therostrum also suggests the existence of soft parts
to connect the fractures bitten off presumably
by Ichthyosaurus (HOlder, 1955, p. 62; Seilacher
and Wiesenauer, 1978, p. 145; Riegraf andReitner, 1979, p. 301). On the other hand, if the
post-mortal floating hypothesis is true and therostrum is completely uncovered and suspended
in the sea water, then Acrothoracican borings
should be distributed over the entire rostral surface with no distinction between proximal anddistal, and between ventral,. dorsal and lateralsides of the rostrum. Observation has affirmedthat this is in fact the case, i.e., borings are
distributed over the entire rostral surface.
So far the hypothesis has been tested
through Acrothoracican behavior, and we havetacitly taken it for granted throughout thepreceding argument that the weight of therostrum counterbalances the buoyancy of air in
the phragmocone, otherwise after death theheavy rostrum of the belemnites would havelittle chance of floating. A question we must ask
then is, "can the belemnite float?" There are twocompeting hypotheses on the original fabric of
the belemnite rostrum, which yield different
values for its apparent specific gravity, and thismay exert an appreciable influence on the
results of buoyancy calculations (Spaeth, 1975,
p. 325; Hewitt and Pinckney, 1982, p. 146). In
this study, however, the heavier specific gravityof the rostrum is chosen, simply because theheavier the specific gravity the greater the possi-

A Story of the Belemnite
bility that buoyancy will become critical. Thusa specific gravity of 2.58 for the rostrum isestimated from the specific gravity of the solid
rostrum of modem squids, which is one of theheaviest structures found in modem coleoid
cephalopods. The volume of the rostrum computed roughly from the curved line shown in
Text-figure 3 is 3.7 cm 3 , so that the estimatedweight of the rostrum is approximately 9.55 g.
Thus, more than 5.66 cm 3 of air is needed tocounterpoise the weight of the rostrum in sea
water. Adopting the shape of the phragmocone
restored through extrapolation of the growthrate of the first 18 chambers (cf. Hanai, 1953,
pI. 6, fig. 4), it is found that this estimatedvolume of air corresponds to the volume of aphragmocone 6.3 cm in length and 1.7 cm inlargest diameter. Of course, a slightly larger
phragmocone with additional air is necessary toaccommodate the weight of the wall of thephragmocone itself and the septa and siphuncle
as well. Yet the restored size of the phragmoconeof Neohibolites miyakoensis falls within the rangeof conceivable size inferred from complete
skeletons of belemnites of some other genera
reported from classical European localities(Engeser and Reitner, 1981, p. 543; Hewitt andPinckney, 1982, pI. 1, fig. 1). Post-mortal flotation may, however, only be possible for certain
specific genera of belemnites whose phragmocone was durable enough and large enough toretain air to float the heavy rostrum. Neohibolites may be one of these genera.
No matter how many tests a hypothesis
passes extensive tests still can not conclusively
prove the hypothesis, and, of course, the evidence is far from conclusive in the case of the
post-mortal flotation hypothesis. Further, so far

131

we have not tested directly the question as towhether the belemnites were alive or dead during
the time of infestation by Acrothoracica, rather
we have tested the question as to whether or not
the rostrum was floating nearly vertically, andexposed or covered by epitherium, and if it wascovered, to what extent was it covered. Yet it
seems to me that the available evidence provides
partial but stronger support for the hypothesisof infestation by Acrothoracica during the timeof post-mortal nearly vertical flotation of thebelemnites.
Hempel (1966, p. 47) explained in his introduction to the "Philosophy of Natural Science"that a scientific explanation needs to satisfy twointerrelated basic requirements. One is therequirement of explanatory relevance in which
the explanation should have "a clear, logicalbearing on our experience", and therefore"afford good ground for believing that thephenomenon to be explained did, or does indeed
occur". The other is the requirement of testability in which the explanation "must be
capable of empirical test". Seilacher's explanation fulfilled these requirements perfectly following the procedure of "method of hypothesis".
For this reason, Petriconi (1971, p. 143) and therest of us could pursue the argument further.
We have to admit that paleontology still retains its "old fashioned" constitution (Seilacher,1968, p. 285). Makiyama (1935, p. 253) deplored the limitations of the studies on the phylogenetic tree of a certain species group of thegastropod genus Umbonium using a simile thatboasting about one's phylogenetic tree is similar
to boasting about the shape of a tree in one's
own garden, others are at a loss about what todo, except for just praising it. What he really

Text-fig. 3. Simplified outline of restored Neohibolites miyakoensis (x 1). Restoration isbased on the specimens figured in Hanai (1953, pi. 6, figs. 4, 5 and 1981, pi. 66, fig. 1).

132

Tetsuro HANAI

deplored might be the non-testable aspects ofthese trees. In connection with this, I havementioned that "the phylogenetic tree is convenient for summarizing the inferred evolutionary histories of groups of organisms in higher
taxonomic categories. However, it may be moreinjurious than beneficial for illustrating therelationships of descendants at the intra-specificand inter-specific levels, in that it conceals the
dynamics of speciation in the dendritic expressions" (Hanai, 1977, p. 85).
Mayr (1963, p. 65) related in his textbook ofsystematic zoology that "Previously, when asked
to explain their theory of classification, taxonomists had been singularly inarticulate". Thisagain leads to the non-testable aspects of classification and may be one of the main reasons why
systematic zoology is undergoing excessive
decline despite its successes in scientific discoveries and in producing evidence throughout
the history of biology, as discussed by Simpson(1962, p. 42). I have once described that a
specimen is different from closely similar species
in having such and such morphology and therefore the animal should belong to a new species.
But now I reflect upon the slightest logical connection between the inference that is to be a new
species and such and such a morphological fact,
where the explanation was far from meeting therequirements of explanatory relevance andtestability.
The aforementioned story of the belemnite
as well as the stories on the phylogenetic tree
and on classification are all hypotheses witha singular character (Popper, 1957, p. 107), andmay be testable at least in principle. In fact,arguments concerning these hypotheses wereonce a driving force for the study of particular
entities (e.g. taxon). The testability of thesehypotheses have been maintained throughlogically linked long sequences of arguments
full of auxiliary assumptions that are tacitly
assumed to hold true. However, the enlargementof our stock of knowledge easily results in a
break somewhere in the logical sequence of thesearguments, usually because the auxiliary assump-tion on which the hypothesis will yield a test
implication is no longer consistent with our
newly gained experience, as for example in thecase of the forward swimming hypothesis forbelemnites when Petriconi came across observations on the unique behavior of the cypris
larvae of boring barnacles. Without the aidof auxiliary assumptions, the hypothesis
easily become virtually non-testable, and,in fact, when Makiyama deplored the nontestability of the phylogenetic tree of Umbonium, and when the good old-timers could notgive logical explanation of their classificationof a particular taxon, these hypotheses (Le. thephylogenetic tree and classification) could beseen to be virtually non-testable. In many cases
in paleontology, it seems long overdue that
explanation should have "a clear, logical bearing
on our experience" (Hempel, 1966, p. 47), andhence should 'be testable through "empiricaltests" (Hempel, 1966, p. 49). In some respects,
paleontology is an unending effort to find a way
out of the impasse of the seemingly non-testableaspects of the study of fossils by inventing a new
auxiliary assumption or a new series of auxiliary assumptions.
References Cited
Codez. J. and Saint-Seine, R. 1957. Revision
des Cirripedes acrothoraciques fossiles. Bull.
Soc. geol. France, ser. 6, tome 7, p. 699719, pIs. 37-39.
Crisp, D. J. 1953. Changes in the orientation of
barnacles of certain species in relation towaster current. J. animo Ecol., v. 22, no. 2,
p.331-343.
--.1955. The behaviour of barnacle cyprids inrelation to water movement over a surface.
J. expo Bioi., v. 32, no. 3, p. 569-590.
- - . 1961. Territorial behaviour in barnacle
settlement. J. expo Bioi., V. 38, no. 2, p.
429-446, pI. 1.
and Barnes, H. 1954. The orientation anddistribution of barnacles at settlement withparticular reference to surface contour. J.
animo Ecol., V. 23, no. 1, p. 142-162.
- - and Knight-Jones, E. W. 1953. The mecha-

A Story of the Belemnite
nism of aggregation in barnacle population.
A note on a recent contribution by Dr. H_
Barnes. J. animo Ecol., v. 22, no. 2, p. 360362.
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Ecol., v. 26, no. 1, p.179-196, pi, 6.
Engeser, T. and Retner, J. 1981. Beitriige zur
Systematikvonphragmokontragenden
Coleoiden aus dem Untertithonium (Maimzeta, "Solnhofener Plattenkalk") von Solnhofen und Eichstatt (Bayern). Neues Jahrb.
Geol. Paliiontol., Monatsh., 1981, Nr. 9,
p.527-545.
Hanai, T. 1953. Lower Cretaceous belemnites
from Miyako district, Japan. Jap. J. Geol.
Geogr., v. 23, no. 4, p. 63-80, pis. 5-7.
- - . 1974. Cirripedia (p. 233-239). In T.
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- - . 1975. No title, Public Relat. Bull. Fac.
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In T. Hanai et al. Checklist of Ostracoda
from Japan and its adjacent seas. Univ. Mus.,
Univ. Tokyo, Bull. no. 12, 110 p., 4 pis.
- - . 1982. A story of the belemnite - developmental approach to fossil morphology.
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Hempel, C. G. 1966. Philosophy of naturalscience. Foundations of philosophy series.
Prentice-Hall, Englewood Cliffs, New Jersey.
116p.
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Hiro, F. 1939. On the barnacle communities at
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HOlder, H. 1973. Auf Fluchtyersuch weisende
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pI. 2 (figs. 5, 6).

133

Jeletzky, J. A. 1966. Comparative morphology,
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Mollusca, Artic. 7,162 p., 25 pis.
Jordan, R., Scheuermann, L. and Spaeth, C.
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p.332-343.
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Knight-Jones, E. W. 1953. Laboratory experiments on gregariousness during settling in
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pI. 16.
--and Crisp, D. J. 1953. Gregariousness inbarnacles in relation to the fouling of ships
and to anti-fouling research. Nature, v. 171,
no. 4364,p. 1109-1110.
Makiyama, J. 1935. Morphogenetic history ofUmboniidae. Venus, v. 5, no. 5, p. 241-255.
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Mayr, E. 1969. Principles of systematic zoology. McGraw-Hill Book Co., 428 p.
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palaontologische Monographie. Verlag von
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Petriconi, V. 1971. Zur Schwimmrichtung derBelemniten und Okologie bohrender Cirripedier. Palaeogeogr. Palaeoclimatol. Palaeoecol., v. 9, no. 2, p. 133-147.
Popper, K. R. 1957. The poverty of historicism.
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and adaptational history of belemnites.

134

Tetsuro HANAI

Neues Jahrb. Geol. Palaontol., Abh., Bd.
157, p. 145-149.
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Smith, F. G. Walton 1946. Effect of water
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vom Primiirgefiige der Hartteile. Palaontol.
z., Bd. 49, Nr. 3, p. 321-331.
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Acrothoracican barnacle, Trypetesa lateralis.
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Turquier, Y. 1970. Recherches sur la biologie desCirripedes Acrothoraciques III La metamorphose des cypris femelles de Trypetesa
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(in Japanese).

(In preparing the English translation of thisaddress for publication, I have found the Japanese manuscript in places lacking in sufficient
explanation for English translation. Therefore,
I have made some additions to give supplementary explanation in the English translation.)

Acknowledgments
The "Story of the belemnite" was deliveredin two separate addresses made in 1981 and1983. Dr. G. E. Wermund of the Bureau of
Economic Geology, the University of Texas atAustin, Austin, Texas and Drs. J. E. Hazel andT. M. Cronin of the United States Geological
Survey, Reston, Virginia aided me in preparation of the English translation of the first address
with the subtitle "developmental approach tofossil morphology". English translation of thesecond address with the subtitle "an approachbased on the method of inventing auxiliary
assumptions in paleontology" was read by Dr.
D. D. Swinbanks of the Ocean Research Institute, the University of Tokyo, Tokyo. They
all made many valuable suggestions andcomments on the contents of these papers,
greatly improved the manuscripts by making
the English expressions more clearly understandable, and encouraged my effort to publish
the English translations of the address. To allthese people I would like to express my sincere
thanks for their help.

Trans. Proc. Palaeont. Soc. Japan, N. S., No. 131, pp. 135-158, pIs. 28-35, September 30,1983

765. OSTRACODA FROM THE PLIOCENE ANANAIFORMATION, SHIKOKU, JAPAN- DESCRIPTION -*KUNllIIRO ISHIZAKI
Institute of Geology and Paleontology, Faculty of Science,
Tohoku University, Sendai 980

Abstract. Thirty-five' out of the samples which Katto et al. (1953) studied forfossil foraminifera provided a variable number of ostracode specimens. Systematicstudies of those materials led to the discrimination of 79 ostracode species distributed among 42 genera in the Ananai Formation whose occurrence by samples islisted. In addition, seven new species (Buntonia parascorta, B. scorta, B. u-carinata,
Callistocythere ananaiensis, C. kattoi, Cytherella japonica, and Krithe hanaii) and
four unnamed species are described.
The ostracode faunas of the Ananai Formation include more of a variety ofelements than have hitherto been reported from the upper Cenozoic of Japan.
They include elements of the upper Cenozoic of Taiwan and of such southern
regions as the Indo-Pacific, Austral-Tasman, and Nova-Zealand Realms, all as
designated by Benson (1964), and have some features in common with those of
the shelf area of the East China Sea, particularly its outer portion.
The occurrence of Bairdoppilata, Doratocy there , and Jugosocythereis? represents the first record from the upper Cenozoic of Japan.

subjacent Nobori Fomration may be of global
importance because it represents the type sectionof Globorotalia tosaensis described by Takayanagi and Saito (1962) and is representativeof Zone N. 21. This formation yields, however,
only scarce ostracode remains which are notsuitable for analytical studies of. ostracodeassemblages. From studies up to this point, it
appears that the assemblages are composed
mainly of such genera as Buntonia, Cytheropteron, Hirsutocythere? Krithe, Palmenella, andPalmoconcha. On the other hand, the Ananai
Formation superjacent to the Nahari Formation
yields abundant and divesified fossil ostracodes,
and most of the samples dealt with, which Katto
et al. (1953) previously studied for paleontology
of foraminiferal remains, yielded a great number

Introduction
The Tonohama Group, which is sporadically
distributed along the eastern coast of Tosa Bay
which abuts the southern border of Shikoku,
yields abundant fossil remains, and so has been
subjected to indisputable stratigraphical andpaleontological studies by many authors since
Yabe (1918) investigated the Operculina-bearing
beds in Japan. The group consists, in ascendingorder, of the Nobori, Nahari (=Ropponmatsu),
and Ananai Formations with the stratigraphic
relationships which have been 'variously assumed
among the authors (Katto et al., 1980). The
Nahari Formation is of nonmarine origin. The* Received July 13, 1982.
135

Kunihiro ISHIZAKI

136

TOKUSHIMA
PREFECTURE,,(~--"- ...

,-- ... --~

-,,
.'
"

.

N

10

20

JOkm

9

Text-fig. 1. Outcrop locations of the Ananai Formation studied.

of ostracode specimens that are sufficient for
faunal analysis.
As part of his long range study, Ishizaki(1979) showed the distribution of fossil ostracode assemblages in the Ananai Formation as
determined on the basis of the scores of the first
three principal components, and suggested
plausible depositional environments of theformation. This paper is intended to complementthat previous study (Ishizaki, 1979) by giving
full descriptions of new and imperfectly known
ostracode species detected in the 35 rock samples
which were collected at the five isolated localities
of Ananai, loki, Tonohama, Ono, and Sempuku
and by listing the occurrence of ostracode specimens of various taxa by sample.
In recent years, the ostracodes of the marine
upper Cenozoic of Japan and those of modem
sediments of the adjacent seas have been more
intensively investigated than ever by such authors
as Ishizaki (1963, 1966, 1973), Hu and Yang
(1975), Ishizaki and Kato (1976), Hu (1976,

1977a, b, 1978,1979), Nohara (1976a, b,1981b,c), Nohara and Miura (1977), Hu and Cheng(1977), Yajima (1978, 1982), Hu and Yeh(1978), Okada (1979), Malz (1980a-c), Ikeya
and Hanai (1982), Frydl (1982), and so forth.
These ostracode studies, particularly those by
Hu and his collaborators in Taiwan, may makea large contribution toward an understandingof ostracode faunas in such southern areas ofJapan as the Ryukyu Islands, Kyushu, andShikoku which includes the present area understudy. In addition, the study of ostracodes inthe East China Sea and its adjacent seas, which
has recently been accelerated by such authors
as Nohara and Tomoyose (1977), Ishizaki (1977,1981), Wang, Min, and Bian (1978, 1980),
Wang, Min, Bian, and Zhang (1979), Kim (1979),
Wang, Lu, and Cheng (1980), Wang, Min,and Gao (1980), Nohara (1981a), and others,
is another important source of information
on ostracodes in those areas of Japan mentioned
above.

765. Ostracoda from the Ananai Formation

137

Samples and Methods

Overview

All the samples employed for this study werecollected at certain stratigraphic intervals by
Katto, one of the cooperative authors of Kattoet aZ. (1953) at the five isolated localities ofAnanai, loki, Tonohama, Ono, and Sempuku(Text-fig. 1, Table 1), and has already beenstudied by them for fossil foraminifera. According to them, each of the samples having a dry
weight of 50 g was disintegrated by using a roller
mill for 15 to 30 min., and washed by tap water
through a 200 mesh screen.
As far as possible, 200 ostracode specimens
were picked at random from the fraction between 12-mesh and 115-mesh screens and examined mainly under a binocular microscope.
A systematic study of the ostracode specimens
taken from those samples was done throughcomparative studies with materials describedby Brady, deposited at the British Museum(Natural History) and the Hancock Museum,
Newcastle-upon-Tyne, and with those describedby Homibrook and Swanson at the New ZealandGeological Survey_ Constant reference was also
made to the extensive literature, including therecent accounts mentioned in the introduction.
The number of ostracode specimens of various
taxa by sample, given in Table 2, represents
the larger number of the two valves. The sample
numbers of the thirty-five samples which yielded
ostracode specimens have letter prefixes which
represent particular localities (Table 1). The
detailed locations of those localities have been
mapped by Katto et aZ. (1953).
In order to perceive which physical agents
then prevailed, grain-5ize analysis was made by
Dr. Yoshihiro Tanimura, now of the Departmentof Paleontology, National Science Museum,
Tokyo, of most of the rock samples employed
for this study, using an automatic grain-5ize
analyser detailed by Niitsuma (1971). Only theMdq, and the mud content are quoted later in thesystematics section. The full results of his work
will be utilized elsewhere in association withthose from the faunal analysis of ostracodeassemblages in order to better comprehend
depositional environments of the formation.

The Ananai Formation, the uppermost unitof the Tonohama Group, generally yields
abundant remains of fossil ostracodes. Thirtyfive out of the samples which Katto et aZ. (1953)
studied for fossil foraminifera provided a variable
number of ostracode specimens. Systematicstudies of those materials resulted in the discrimination of 79 ostracode species distributed among
42 genera, including seven new and four unnamed species. The occurrence of those species
by sample is listed in Table 2. That table showsthat the ostracode faunas of the Ananai Formation include a variety of elements which have hot
been found in the upper Cenozoic of Japan, fromthe Ryukyu Islands up to the areas farther north.
As an example, listed below are the species whichhave been reported by Hu and his collaboratorsfrom Taiwan.
Bythoceratina
dip Zeu ra(=Monoceratina
dipZeura Hu and Cheng, 1977),
Callistocythere ovata Hu, 1976,
Cytheropteron rhombea Hu, 1976,
Doratocythere
taiwanensis(=BassZerites

Table 1. Sample locations
0: Southern slope, immediately north ofAnanai, Aki City, Kochi Prefecture. 01 is
5.5 m above PI
P: The same locality as the above. P3 to PI in
ascending order at an interval of 1.5 m
L: loki, Aki City. Ll, 5 m above Ml, to L4 inascending order at an interval of 3 m
M: The same locality as the above. Ml is 5 m
below Ll
K: 150 m north of Tonohama, Yasuda town,
Aki County, Kochi Prefecture. K11 toKl in ascending order at an interval of
1.5m
H: 80 m west of Ono, Yasuda town, Aki City.
H4, 2 m above 11, to HI in ascendingorder at an interval of 1 m
I: 110 m west of Ono. 11, 2 m below H4, to
12 in descending order at an interval of
1.5m
J: 150 m northwest of Ono. Jl is 8 m below 12
G: 150 m west of Sempuku, Nahari town, Aki
County. G8 to Gl in ascending order at
an interval of 1 m

138

Kunihiro ISHIZAKI
Table 2. Distribution of ostracode specimens of various taxa by sample.

Specific name.
1 Actinocytnerei.s kisa1'a.auensis Yajlma, 1978
2 AZocopocythel"8 gouJoni (Brady, 1868)
3 Ambocythere japonica Ishizakl, 1968
4 AT'giZloeda hanaii Ishlzaki. 1981
5 Aurila C!ymOO (Brady, 1869)
6 Au1'ila hataii Iahizaki, 1968
7 AUl'iZa munechikai Ishlzakl, 1968
8 Aurila tosaensis Iahlzaki. 1968

9 AuriZa uI'aTIOuchiensis Ishizakl. 1968
10 BairdoDDilata 8'D.
11 BicoT'nucythsr8 bisanensis (Okubo. 1975)
12 Bradleya albatrosBia Benson, 1972
13 Brodleya nuda Benson, 1972
14 Buntonia hanaii YajilD8.. 1978
15 Buntonia paMBCOl'ta n • • p.
16 Btmtonia 8COT'ta n. sp.
17 Bw!tonia u-eat'inata n. ,po
18 Bythoceratina dipleW"a (Mu and Cheng, 1977)
19 Bythoeeratina hanaii Ishizakl, 1968
20 B thoC81'O.tina cf.ot'ientatis Brady. 1869)
21 Ca~~~stocyt,!el'e auzta Hanai, 195
22 Callistocythere ananaienai8 n. sp.
23 Callintocythel'e japonica Hanai, 1957
24 CaZlistocythe1'6 kattoi n. sp.
25 Callistoaythe1'6 ouata Hu. 1976
26 CallintoaytheJ>e tmdata Hanai, 1957
27 Calliatocythere ap.
28 Coquimba ishizakii Yajima. 1978;t~~~:q~= =:~~:a~i~~i~:~!i li~~~

31 Cyt~el"e~~a Japorn.c:a n. sp.
32 Cytherelloidea hanaii Nohara, 1976
33 Cytherelloidea nabahensi8 Keij. 1964
34 Cytherelloidea ct. yakenaen8iB Nohara. 1976
35 Cytheroptel'On l1Tiul"ense Hanai, 1957
36 Cytheropteron rhombea Hu. 1976
37 Cytheroptel'On !whioi Hanai. 1957
38 Dol'O.to<:'ytheJ>e tailJanenai8 (Hu and Yeh. 1978)
39 Echi'l1OL·ythereia? bradyfonnin Ishizaki. 1968
40 HemiClJthcl"Uru catJa Hu 1977)
41 Herrtieytheroura ct4neata Hanai. 1957
42 Henricytlzerura ka,jillamai Hanai. 1957
43 Hemiaythe1"U1'Q zoadiata Hornibrooit. 1952
44 HirGutocythere? hanaii Iahizaki, 1981
45 Jugosocythereis Bp.
46 Kobayaehiina hyati'l1Osa Hanai. 1957
47 Krithe hanaii n. sp.
48 Krithe producta Brady. 1880
49 Lixouna 'lipponiea Yajilll<l. 1978
50 LozQCollcha hatton i Iahizaki. 1971
51 Loxoeol1crya Japol!~ea Ishizalti. A~~ttll
52 Lozoconcha kattoi Iahizaki, 1968
53 Lozocol1cha optima Ishizaki, 1968
54 Loxoeonaha sinemlia Brady, 1869
55 Lo%Oco1"7liculWTI mutnuense Ishizaki, 1971
56 Ma~l'Ol.·ypns decol'O. (Brady. 1866)
57 Mul18eyelLa ObOl'O::l,kiyo Yajima, 1982
58 Mt.rl8eyclla japonica (Hanei, 1957)
59 MutiZull noduloHWTI (Hu. 1977)
60 Neonesidca. villosa (Brady, 1880)
61 Nt.pponoC'yt,!ere otcaJ>l.na~ Braay,.:DDU1
62 Paijenborehella ioeosa Kingma. 1948
63 PaiJenbol'Chella nn.!d"en8iB Hanai. 1970
64 Paijertbol'Chella tl"itmgulari8 Hanai, 1970
65 Para~ytheridea ct. bosoensiB Yajima. 1978
66 Pa:racytheridea l'teoZongicaudata Ishizaki, 1966
67 Paraknthel.la pseudadonta (Hanai, 1959)
68 Pontocythel'e japonica (Hanai. 1959)

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2
1
1

2
11
2
8
2
2
2
2
2
J5

1l
2
8
1
1
5
2
J
14

3
1

2
8
1
1

,
1
1
7
J
3

1

4

1

2

3

1
14

1
2
14

2
12

8

15

14

J
2

1
5
J

5
1

71 Pterygoaythel'e'L8 Gaa QM.S (Brady. 1880)
72 Schizocythel'e kiflhinouyei (Kajiyama, 1913)
73 Serrticythel'Ul'Q hanaii Ishizaki. 1981
74 Serrricythel"Ul"Q henroyhoLJei Hanai and lkeya. 1977
75 7'ro.chyleberois lungkangensis Hu and Cheng. 1977
76 Trachyleberis? tOBaen8iB Iahizaki. 1968
77 Xestoleberis hanaii Ishizaki. 1968
78 Xestoleberis sagamiensis Kajiyama. 1913
79 Xestol.:bel"is sp.

- - - - - - ,- - - , - •- - - - - - - - ,, - - , , - ,,- - - - - - - - ,- , ,- ,- - - •,
- - - l'- - - -, - - - •- - - - - - , - -- - - ,- l' -- •,, , - , , , , , , ,•• , - -Total number of individua1a

58 202 202 207 200 206 239 232 20~ 230 242 235 244 225 218 230 254 207~~ ~;=~~ ~~~:s (~:~~:!ki 19i:!8)

2

7

7

1

- -

1

J
5
1
1

-

-

-

52

1
2

2
79

3

4J
1

J
5
19
1

1
1
J
11
1

2

8
2

1J

5

3
8

12

1

J
2
1

3
5
3

1
1
1

2
J
J
2

-

10
1
1
10
1
2
1

1
23
1
1
1

5
1

1J

9
1
2
1

14
1
2
J
1

2
2
10
1
2
2
3
1
1
7
5
J
2

1
1
5
1

17
2
2

1
1
15
1

12
12
4
5
1

5
2
2

1

1

2

2

18

2

1
22
J

1

8

1
1.
11
5
J

4
22
8

J

1
J

17
1
J
1
13

J
20
8

-

1l

4
1
3

2

1

1

1

12

11
1

1
1J
2
3
13

5
8

18

1
2
1

5
3

J
13
1
2

1
2
15
1
7
5

-

12

1
3
15

10
3
5
2

-

765. Ostracoda from the Ananai Formation

KIO Kll

HI

HZ

H3

H4

11

-

2
2

1
3

1

1
-

1
1

-

1

1

2

11

5

-

B

5
B

7

9
10
11
12
13
14
15
16

-

2
3
5
9
1
4

2

-

-

2B

"

30
31
32
33
34
35
36
37
3B
39
40
41
42
43
44
45
46
47
48

49
50
51
52
53
54
55
56
57
58

59
60

61
62
63
64
65
66
67
68

~~
71

72
73

74
75
76
77
78
79

GZ

-

G]

4

2

2

6

G4

G5

G6

2

-

2

2

2

1

3

4

5

18
19
20
21

27

Gl

G7

GS

-

2

7
5
8
6
1
2
1
5
6
1
7113841-2-58341_1
3
6
3
1
1
1-4
2
]

"

J!

5
3
6
9
2
5
5
47413-7_5
8-441--2
2-132
1
2
7
4
2
4
5
4
1
4
B

17

23
24
25
26

12

2

3

2-2--1
3
1
1
-

1

6
7
-

2
2

1

1

1
2
3
1
1
2
3
4
2
2
5
]
7
4
3
1
4
15 12
5 13
- 21
21 21 17 18 21
2 14
1
1
6
2
1
1
3
6
3
1 11
7 11
1
5
3
6
B
5
1
1
2
2
1
]
4
3]2-2)--1-35--4
1
1
1
1
1
1
1
1
2
1
2
1
2
3
2
1
1
1
2
2
2
2
1
2
1
5
2
1
4
1
1
3
2
2 11
1
--111-53645-1
4
5
1
5
1
6
3
1
3
5
]
3
3
4
3
5 12
3
2
1
1
2-2-5
5---7
4
6
3
1
1
6
6
6
1
2
2 19
)
B 19
6
7
4
2
3
1
3
2
3
1
1
7
28
1
16

;

-

16

5

3

1

13

-

1

-

16
2

4
2

2

1
7

-

-

13

-

-

2

-

1

-

-

6

1
13

6

1
6

1
10

-

1

1

-

2
1
3 11
1
5
55-4436-2--33-3-2
-2
718
--8
5 14
7
5
3
1
1
3
1
1
1
1
1
2
1
5
-1-----1114
9
4
5
5 14
- 17
- 11 12
8
6
7
1
3
2
2
3
7
6
]
1
J
2
1
3
5
8 23
32 23 20
4 23
- 25 23
8 23 13
6-2-1-1-1-3
1
2
2
121
5 11
7
7 12
9
- 11
4
8
3
2
1
1
1
2
1
2
1
2
-1---11----11
3
12 18
9
7
8 18 24
8
4
5
6
5
5
1
2
5
1
4
4
1
1
2
3
4
7
1
3
1
3
3' 8
2
3
1
3
1
1

-----1--1-----

1
2
2
1
2
1
5
2
40
18 10 30 32 30 20 39
23 20
1
2
1
1
2
1
1
1
1
1
3
2
1
1
19
16 16 15
8
4
7 14
3 13
- 15
1
1
2
4
1
1
1
5
1
1
2
10
8 13 11 11
5
8
6
10 20
32211573-3-88-2---4--2
2
2
1
4
3
1
2
2-2--1-

203 209 236 237 299 205 225

24 239

1

1

1

20

26

21

3

10

21
1

3
12
2

14

1

13

-

2

1

-

12
7
1

4

-

5

-

1

13

73

-

1

4

12 240 269 207 239 208

139

taiwanensis Hu and Yeh, 1978),
Hemicytherura cava (=Kangarina cava Hu,
1977),
Mutilus nodulosum (=Radimella nodulosa Hu,
1977), andTrachyleberis lungkangensis Hu and Cheng,
1977.
Of these, four species, B. dipleura, C. ovata,
C. rhombea, and T. lungkangensis have alreadybeen recognized by Ishizaki (1981) in the shelfarea of the East China Sea. Herewith, the remaining three species have now also been recognizedfrom the Japonic Realm as described by Benson(1964).
On the other hand, the following eight species
discriminated in the Ananai Formation havebeen reported from the Indo-Pacific, AustralTasman, and Nova-Zealand Realms, all as
designated by Benson (op. cit.):
Alocopocythere goujoni (Brady, 1868),
Bradleya albatrossia Benson, 1972,
Cytherelloidea sabahensis Keij, 1964,
Hemicytherura radiata Hornibrook, 1952,
Krithe producta Brady, 1880,
Macrocypris decora (Brady, 1866),
Neonesidea villosa (Brady, 1880), andPterygocythereis scalaris (Brady, 1880).
A. goujoni has been reported in the area westof Carimata between Poulo Condore and Billiton
Island, in Hong Kong Harbour, in the Bay ofManila, and in the Pliocene of Timor (Brady,
1868, 1880; Key, 1954; Hanai et al., 1980);
B. albatrossia in the area off Hong Kong, off
Ki (Kai) Island, north of Sarawak, and Batu
Island (Benson, 1972; Brady, 1880; van den
Bold, 1950); C. sabahensis in the area off Sabah,
northwest of Borneo (Keij, 1964); H. radiatafrom the upper Eocene to Recent in New
Zealand (Hornibrook, 1952); K. producta in
the area off Sydney, in the Tasman Sea and theCoral Sea (Brady, 1880); M. decora along thenorth coast of Java and Batavia and the west
coast of Sumatra (Hanai et al., 1980; van den
Bold, 1950); N. villosa in the area north of
Sumatra, and in Bass' Strait (van den Bold,
1950; Brady, 1880); and P. scalaris in Torres

Kunihiro ISHIZAKI

140

Straits and in the area north of Sarawak (Brady,
1880; van den Bold, 1950).
Except for B. albatrossia, whose referable
fonn has been recorded by Nohara (1981c)
in the Pleistocene Naha Limestone of Okinawa,
all of these species have already been discriminated by Ishizaki (op. cit.) as occurring in the
shelf area of the East China Sea.
As mentioned above, the ostracode faunas of
the Ananai Fonnation include elements of theupper Cenozoic of Taiwan as well as of such
southern regions as the Indo-Pacific, AustralTasman, and Nova Zealand Realms, and show aclose resemblance to those in the shelf area of
the East China Sea, where, particularly in its
outer portion, the agency of the Kuroshio
Current is sufficient to result in frequent occurrences of those elements.
When using a modern analogue, knowingthat the two different settings have such featuresin common would be very important for understanding depositional environments of theAnanai Fonnation and the then prevailing
oceanography.
In addition to the above-mentioned species,
the species described herewith as new are
Buntonia parascorta, B. scorta, B. u-carinata,
Callistocythere ananaiensis, C. kattoi, Cytherellajaponica, and Krithe hanaii.
On the generic level, Bairdoppilata Coryell,
Sample, and Jennings, 1935, Jugosocythereis
Puri, 19577, and Doratocythere McKenzie, 1967,
are initially discriminated in this study as existingin the upper Cenozoic of Japan.

Systematics
The initials "IGPS" used with the type andillustrated specimens stand for the collection of
the Institute Of Geology and Paleontology,
Faculty of Science, Tohoku University, Sendai,
Japan. The frequency of each taxon is denotedby the expressions defined by Ishizaki (1981)
on the basis of a probability of 0.05 at which no
specimen of a certain taxon will be encounteredin a sample.

Subclass Ostracoda Latreille, 1806
Order Podocopida MUller, 1894
Suborder Platycopina Sars, 1866
Family Cytherellidae Sars, 1866
Genus Cytherella Jones, 1849
Cytherella japonica n. sp.
PI. 32, Figs. 3,4, 6, 7

Diagnosis. -Carapace moderate to large, thickshelled, oblong. Almost entire surface smooth,but four to five subparallel costae along anterior
brim, and those in addition to minute granulareminences along posterior brim.
Description. -Carapace moderate to large,
thick-shelled, oblong with greatest height nearposterior third or anterior tenninal of dorsal
margin in lateral view, somewhat ventrally
deflated at mid-length, and wider posteriorly.
Dorsal margin slightly sinuous, more or lessconcave near anterior third and broadly archedin posterior two-thirds in left valve, but almost
straight in right valve. Ventral margin nearlystraight, or slightly concave near mid-length.
Anterior margin symmetrically and broadly
round, merges into dorsal and ventral margins.
Posterior margin broadly round slightly below
mid-height, meets dorsal margin fonning abroadly round corner. Almost entire surface
smooth except for narrow anterior and posterior
marginal areas; very finely corrugated or four tofive subparallel costae discernible in anterior
brim, and those in addition to minute granulareminences in posterior brim. No eye tubercle
nor ocular sinus discernible. Smaller pores
simple, flush, widely spaced. Larger pores, possibly broken sieve-plate pores, rarely found.
In internal view, outer margin overpassed byoutline throughout, and slightly concave near
mid-length of ventral margin. Inner lamella notwell developed. Smooth narrow ridge circumscribes entire outer margin of left valve, and anaccommodative groove continuous along inside
outer margin of right valve. Right valve more orless widely overlaps left valve near anterior

765. Ostracodll from the Ananai Formation

third of dorsal margin. Oval muscle scars field
wide, but arrangement of them not very clear
due to poor preservation. Internal openings
of normal pore canals rarely observable, simple,
small.
Type and dimensions. -Paratype, left valve,sample K9 (IGPS 97807, PI. 32, Figs. 4a, b)
0.80 mm long and 0.49 mm high; paratype,right valve, sample H3 (IGPS 97808, PI. 32,
Figs. 3a, b) 0.70 mm long and 0.48 mm high;holotype, left valve, sample H3 (IGPS 97809,
PI. 32, Fig. 6) 0.83 mm long and 0.49 mm high;paratype, right valve, sample K9 (IGPS 97810,
PI. 32, Fig. 7) 0.81 mm long and 0.51 mm high.
Type-locality. -About 80 m west of Ono,
Yasuda town, Aki County, Kochi Prefecture(sample H3).
Remarks. -So far as being known to thewriter, forms of the genus Cytherella of Japan
have only been listed by Nasu and Saito (1958)
as Cytherella sp. a and C. sp. {3 from the recent
silty sand on the shelf off the eastern coast of
the Kii Peninsula, Japan (Kumanonada or the
Gulf of Kumano).
Cytherella japonica somewhat resembles
Cytherella sp. Khosla (1978) from the lower
Miocene of Jamnagar and Porbandar districts,
Gujarat, India, but differs in that the former
is characterized by a shorter and more posteri.
orly widened carapace.
Occurrence. -Common at K1, Kll, H3, andG5 (measured mud content 50.1-68.0%, Mdif>
3.82-3.94); rare at K6, K9, H2, and H4.
Suborder Podocopina Sars, 1866
Superfamily Bairdiacea Sars, 1888
Family Bairdiidae Sars, 1888
Subfamily Bairdiinae Sars, 1888
Genus Bairdoppilata Coryell, Sample,
and Jennings, 1935
Bairdoppilata sp.
PI. 33, Figs. 5, 6; PI. 34, Fig. 4

141

Description. -Carapace very large, moderate·
shelled, extraordinarily unequal in lateral shape,
and widest medially. Right valve subtrapezoidwith greatest height in front of mid-length.
Dorsal margin rather narrowly arched. Ventral
margin sinuous, slightly concave in front of
mid.length, and anterior and posterior segments
arched. Anterior margin narrowly round well
below mid·height. Upper margin long, nearlystraight, meets dorsal margin forming a roundcorner, and merges into dorsal margin. Posterior
margin more or less upturns and acuminate well
below mid-height. Upper margin sinuous, narrow·ly concave just above the acumination, theremaining upper margin broadly arched andmeets dorsal margin forming a round comer,
and merges into ventral margin. Left valve subovate with greiltest height slightly before mid·length, and widest medially. Dorsal margin
rather narrowly arched. Ventral margin slightly
arched. Anterior margin slightly depressedventrally, and rather narrowly round slightly
below mid·height. Upper margin nearly straight,
merges into dorsal margin. Lower margin narrow·
ly rounded well below mid·height. Upper andlower margins arched, and merge into dorsal andventral margins. Surface smooth. No eye tubercle
observable.
External openings of normal pore canals
simple, flush, moderate in size, widely spaced.
Internally, inner lamella wide in lower halfof anterior to ventral marginal areas. A slightvestibule differentiated along lower half ofanterior to ventral marginal areas. Selvage distinct along lower half of anterior to ventral
margins; concave before mid·length of ventral
margin, and stands definitely aside outer margin
in anteroventral and posteroventral areas. Selvage
in anterior and posterior upper margins becomes
thicker and more coarsely crenulate downward.
Muscle scars typical of bairdiids. Five or six
dorsal scars just below dorsal margin.
Dimensio.ns. -Figured specimens, right valve,sample L4 (IGPS 97815, Pl. 33, Fig. 6) 1.28
mm long and 0.82 mm high; left valve, sample

Kunihiro ISHIZAKI

142

L3' (IGPS 97816, PI. 33, Figs. 5a-c) 1.25 mmlong and 0.88 mm high; left valve, sample L1(IGPS 97817, PI. 34, Fig. 4) 1.26 mm long and0.81 mm high.
Remarks. -The present report provides thefirst record of form of the genus Bairdoppilata
from Japan. This form somewhat resembles
Bairdoppilata alcyonicola Maddocks (1969) from
Nosy Be, Madagascar, but differs in that the rightvalve of the former has a posterior terminal muchless distinctly upturned and a more shallowly
concave ventral margin.
Occurrence. -This form was occurred only
from four samples: Abundant at L1 (mud content 61.7%, Mdcp 3.99); common at M1.
Superfamily Cytheracea Baird, 1850
Family Cytherideidae Sars, 1925
Subfamily Krithinae Mandelstam, 1958
Genus Krithe Brady, Cross key , andRobertson, 1874
Krithe hanaii n. sp.
PI. 33, Figs. 1-4; PI. 35, Fig. 9

Diagnosis. -Carapace moderate to large, subovate to oblong with greatest height at posterior
third. Dorsal margin broadly rounded, jutting out
around posterior third. Surface smooth. Internal
openings of normal pore canals very thick,widely spaced.
Description. -Carapace moderate to large,
moderate-shelled, subovate to oblong withgreatest height at posterior third, and widest at
posteromedian . area. Dorsal margin broadly
round, more or less jutting out near its posterior
third. Ventral margin nearly straight, or slightly
concave just behind mid-length. Anterior margin
symmetrically round, ending at mid-height, andmerges into dorsal and ventral margins. Posterior
margin depressed ventrally, ends well below midheight, merges into dorsal margin, and meetsventral margin forming a round acute angle.
Surface smooth. Openings of normal pore
canals thick, widely spaced on entire surface. Eye
tubercle not distinct.

Internally, outer margin concave near midlength of ventral margin. Posterior apparent
opening distinct. Inner lamella wide along
anterior margin, but narrow along the remainingof extracardinal margin. Line of concrescencecoincides with inner margin for the most part
except for a portion just below mid-height,
where narrow but deep vestibule invades into
more than half the width of inner lamella to leadto anterior extension of most of radial pore
canals in anterior margin. Radial pore canals
rather thick, simple, but branch off in some, 16
canals in anterior margin, which are definitely
concentrated in a portion just below mid-height.
Five simple and thick canals discernible in ventral
margin. Hinge pseudoadont. A narrow groove
along inside dorsal margin in left valve rather
deep, crenulate near its anterior terminal and its
posterior half. Muscle scars consists of a verticalrow of four adductor scars, of which lowermost
one round and small, and upper two scars large,
and apparently constricted at their mid-length.
An anterior scar appears to be a fusion of threescars. Three scars, at least, discernible above
adductor muscle scars. Internal openings ofnormal pore canals very thick, widely spaced.
Type and dimensions. -Paratype, left valve,sample K7 (IGPS 97811, PI. 33, Fig. 2) 0.76 mm
long and 0.46 mm high; paratype, right valve,sample K7 (IGPS 97812, PI. 33, Figs. la-c) 0.71
mm long and 0.38 mm high; holotype, left valve,sample H2 (IGPS 97813, PI. 33, Fig. 3, PI. 35,
Fig. 9) 0.90 mm long and 0.51 mm high; paratype, right valve, sample K11 (IGPS 97814, PI.
33, Fig. 4) 0.77 mm long and 0.41 mm high.
Type-locality. -About 80 m west of Ono,
Yasuda town, Aki County, Kochi Prefecture(sample H2).
Remarks. -This species resembles Krithe producta Brady (1880) in many respects, but differs
in that the former has a smaller and shorter
carapace, which projects its posterodorsal margin
more strongly.
Occurrence. -Common at H2, H4, and G5(measured mud content 56.7%, Mdcp 3.94).
Family Leptocytheridae Hanai, 1957

765. Ostracoda from the Ananai Formation

Genus Callistocythere Ruggieri, 1953
Callistocythere ananaiensis n. sp.

PI. 30, Figs. 4, 5; PI. 31, Figs. 1·3; PI. 35, Fig. 2
Diagnosis. --Carapace rather small, thick-shelled, oblong. Surface ornamented with bold anterior and posterior marginal ridges, and two horizontal and vertical ridges.
Description. --Carapace rather small, very
thick-shelled, oblong in lateral view, inflatedaround a horizontal axis at mid-height, and wider
posteriorly. Dorsal margin straight. Ventral
margin broadly concave in front of mid-length.
Anterior margin depressed ventrally, ends slightly
below mid-height, and merges into dorsal andventral margins. Posterior margin more or lessnarrowly protruded postward below mid·height,
merges into dorsal margin in many specimens,
but meets it forming a more or less clear cardinalangle in some specimens, and merges into ventral
margin. Surface ornamentation is fundamentally
characterized by anterior and posterior marginal
ridges, two horizontal ridges, two vertical ridges,
and an anterior oblique ridge, and a ventral ridge.
Anterior marginal ridge very bold and wide along
anterior margin from anterior terminal of dorsal
margin to that of ventral margin, and branches
off a narrower anterior oblique ridge at anterodorsal area, which continues to anteroventral
area. Posterior marginal ridge very bold and wide
along inside posterior margin from posterior terminal of dorsal margin to that of ventral margin.
This ridge widens considerably near lower terminal and becomes obliquely to anteroventral
area where it merges into anterior marginal ridge.
Upper horizontal ridge more or less sinuous, andprominent, runs slightly above mid-height fromanterior oblique ridge to posterior marginal ridge.
This ridge crosses two vertical ridges danglingfrom dorsal margin at an anterior and posterior
third of valve length. Lower horizontal ridge
short, runs from anteroventral area to medianarea and intersects anterior oblique ridge andanterior vertical ridge. Anterior vertical ridge
bifurcate below upper horizontal ridge and connected with ventral ridge. Posterior vertical ridge

143

branches off into two narrower ridges above
upper horizontal ridge, and joins to ventral ridge.
Depressions between ridges generally considerably deep except for median area below upperhorizontal ridge where partly, irregular reticulation observable. Small pits stud the surface ofmost of bold ridges. Rimmed pores simple, rather
large. Eye tubercle not distinct.
Internally, outer margin widely overpassed byoutline posterodorsally. It distinctly concaveslightly before mid-length of ventral margin, andnarrowly curved at posterior terminal of dorsal
margin. Posterior apparent opening distinct at
mid-height. Inner lamella wide along anterior andposteroventral margin. Line of concrescencenearly coincides with inner margin. Radial pore
canals thick, widely spaced in clusters, andbranching off into two or three anteriorly inanterior margin; eight canals along inner margin
diverge anteriorly into 22 canals along outermargin. Radial pore canals moderate in thickness,
simple, and attain to five and 12, respectively, inposterior and ventral margins. Selvage distinct
along inside almost entire extracardinal margin.
List more or less distinct along anterior andventral margins. Hinge entomodont. Median bar
in left valve crenulate, thickens and more coarsely denticulate near its terminals. In right valve,anterior tooth small, smooth, and horizontallyelongate, and posterior tooth small, smooth, andslightly elongate subvertically. Very small snapknob observable at concavity of ventral marginof right valve. Central muscle scars consist of avertical row of four adductor muscle scars, but
frontal scars not clear; apparently fused twoscars. Internal openings of normal pore canals
simple, rather large.
Type and dimensions. -Holotype, right valve,sample H1 (IGPS 97796, PI. 30, Fig. 4; PI. 31,
Figs. 3a, b), 0.48 mm long and 0.25 mm high;paratype, left valve, sample HI (IGps 97797, PI.
3D, Figs. 5a, b), 0.48 mm long and 0.25 mm
high; paratype, right valve, sample H1 (IGPS
97798, PI. 31, Fig. 2; PI. 35, Fig. 2), 0.48 mmlong and 0.24 mm high; paratype, left valve,sample H1 (IGPS 97799, PI. 31, Fig. 1), 0.45 mm
long and 0.25 mm high.

Kunihiro ISHIZAKI

144

Type-locality. -About 80 m west of Ono,
Yasuda town, Aki County, Kochi Prefeeture(sample HI).
Remarks. -This species is closely related to
Callistocythere puri McKenzie (1967) in mostrespects, but is distinguishable in that the former
has much thicker marginal ridges, a more continuous upper horizontal ridge, and two verticalridges instead of three.
Occurrence.-Abundant at L2, K2, K7, HI-3,
11, Jl, G2-6, and G8 (measured mud content
20.5-73.8%, Mdcp 3.53-4.14); common at P2,
L4, L3, Ll, Ml, K3-6, K8, KI0, Kll, and H4(measured mud content 33.4-68.0%, Mdcp
3.75-4.05).
Callistocythere kattoi, n. sp.
PI. 31, Figs. 4-7; PI. 35, Fig. 8

Diagnosis. -carapace moderate to small, thickshelled, rectangular. Surface ornamented with
marginal ridge, ventral oblique ridge, radial
ridges, and coarse reticulation.
Description. -Carapace moderate to rather
small, thick-shelled rectangular or subrhomboid
in lateral view with greatest height at anterior
terminal of dorsal margin, and widest posteroventrally. Dorsal margin almost straight. Ventral
margin broadly concave. Anterior margin depressed ventrally, narrowly rounded below mid-height, meets dorsal margin forming a roundobtuse cardinal angle, and merges into ventral
margin. Lower half of the margin denticulate.
Posterior margin more or less vertically truncated, meets dorsal margin forming a broadly or
narrowly round cardinal angle, and meets ventral
margin forming a narrowly round comer.
Surface ornamented with marginal ridge,
ventral oblique ridge, radial ridges, and reticulation. Marginal ridge circumscribes entire margin;
broader along anterior margin, and thick andprominent on posteroventral margin. Ventral
oblique ridge very prominent and wide fromjust behind anteroventral area to above midheight of posterior margin, ornamented withreticulation, and disrupted in posteromedianarea. Three narrow radial ridges discernible in
mid-anterior area; one extends forward horizontally and the other two run toward anterodorsal area, all joins to marginal ridge at theirterminals. Depressions deep in mid-anterior andposteroventral areas. Reticulation rather coarse,
covers almost entire surface except for the depressions. Eye tubercle not distinct. Rather large
pores simple, open within sola and on muri.
Smaller pores also simple, open on murl.
Internally, outer margin overpassed by outline along posterior two-thirds of dorsal andventral margins, and rather narrowly concave
before mid-length of ventral margin. Inner

Explanation of Plate 28
Figs. 1-4. Buntonia parascorta Ishizaki, n. sp.
1. Adult right valve (Holotype, IGPS 97781; Sample H2).
a. Lateral view, x 120.
h. Part of Fig. la, showing details of external openings of normal pore canals, x 800.
c. ditto.
2. Adult left valve (Paratype, IGPS 97782; Sample H2).
a. Lateral view, x 120.
h. Part of Fig. 2a, showing details of external opening of normal pore canal, x 1,600.
3. Internal view, adult left valve (Paratype, IGPS 97784; Sample H2). x 120.
4. Internal view, adult right valve (Paratype, IGPS 97783; Sample Kll). x 120.
Figs. 5, 6. Buntonia scorta Ishizaki, n. sp.
5. Part of lateral view, showing details of external openings of normal pore canals, adultleft valve (Paratype, IGPS 97785; Sample H2). x 1,200.
6. Part of lateral view, showing details of lateral surface, adult right valve (Paratype, IGPS
97786; Sample G5). x 1,200.

ISHIZAKI: Ostracoda from the Ananai Formation

Plate 28

765. Ostracodll from the Ananai Formation

lamella wide along anterior and posteroventral
margins. Vestibule very narrow along anterior
and posteroventral margins. Radial pore canals
thick, widely spaced, often bulbous at anterior
fourth of their length, and bifurcate in manycases. Eight canals along inner margin diverge
anteriorly into 18 canals along outer margin inanterior margin. Four and 14 canals discernible
in posterior and ventral margins, respectively.
Selvage distinct along entire extracardianl margin. Hinge entomodont. Median bar in left valve
finely crenulate, distinctly thicker and morecoarsely denticulate anteriorly, and slightly
thickens posteriorly. In right valve, anterior
tooth horizontally elongate and trilobate, andposterior tooth round and smooth. A small snapknob discernible at concavity of ventral marginof right valve. Muscle scars consist of a verticalrow of four tightly spaced adductor muscle scars.
Fused two scars in front of them. Internal openings of normal pore canals rather thick, widely
spaced.
Type and dimensions. -Holotype, left valve,sample H1 (IGPS 97800, Pl. 31, Fig. 5) 0.53 mm
long and 0.35 mm high; paratype, right valve,sample H1 (IGPS 97801, PI. 31, Figs. 4a-c), 0.53
mm long and 0.30 mm high; paratype, left valve,sample H1 (IGPS 97802, Pl. 31, Fig. 6; PI. 35,
Fig. 8), 0.53 mm long and 0.31 mm high; paratype, right valve, sample H1 (IGPS 97803, PI. 31,
Fig. 7) 0.53 mm long and 0.30 mm high.
Type-locality. -About 80 m west of Ono,
Yasuda town, Aki County, Kochi Prefecture(sample H1).
Remarks. -In respect of fossae which coveralmost the entire surface, this species somewhat
resembles Callistocythere dorsotuberculata Hartmann reported by Hartmann (1980) from thesoutheastern coast of Australia, but the former
has a rectangular or subrhomboid lateral outline,
and a much more prominent and wide ventral
oblique ridge.
Occurrence. -Abundant at L3, L2, M1, H1,
H3, and 11 (measured mud content 56.8-73.8%,
Mdl/> 3.90-4.14); common at L4, L1, K1, K2,
K4, K5, K10, Kll, H4, J1, G2-4, G6, and G8(measured mud content 20.5-68.0%, Mdl/> 3.533.99).

145

Callistocythere sp.
PI. 32, Figs. 1, 2, 5

Description. -Carapace moderate in size, thickshelled, oblong or subrhomboid with greatest
height at anterior cardinal angle in lateral view,
and widest posteroventrally. Dorsal margin
broadly arched. Ventral margin slightly sinuous,
broadly concave in anterior two-thirds, butslightly arched in a posterior third of the length.
Anterior margin rather strongly depressedventrally, narrowly rounded well below midheight, meets dorsal margin forming a vague
obtuse cardinal angle, and merges into ventral
margin. Lower section of the margin denticulate.
Posterior margin narrowly protruded postward
above mid-height, meets dorsal margin forminga more or less distinct cardinal angle, and merges
into ventral margin.
Surface fundamentally ornamented with two
marginal ridges, as many horizontal ridges, andfour vertical ridges. Outer marginal ridge moderate in thickness and circumscribes entire
margin. Inner marginal ridge thicker, and runs
along inside anterior, ventral, and posterior margins from anterior cardinal angle to before
posterior cardinal angle. It deverges for a small
distance near anteroventral area and in front of
posterior margin. Lower horizontal ridge starts
forward from median area to mid-anterior area
between outer and inner marginal ridges. Upper
horizontal ridge runs postward from anteromedian area to posteromedian area, and then itturns and continues parallel with inner marginal
ridge to just before posterodorsal area. Of four
vertical ridges, anterior one dangles from anteriorcardinal angle to near anterior terminal of upperhorizontal ridge; second one from an anterior
third of dorsal margin to upper horizontal ridgein median area; third one from mid-length of
dorsal margin to the posterior section of upperhorizontal ridge in posteromedian area; fourth
one from a posterior third of dorsal margin to
the posterior section of upper horizontal ridgein posteromedian area. A short ridge crosses
between the second and third vertical ridges ata lower third of their length. Eye tubercle notdistinct. Smaller pores simple, widely spaced,146

Kunihiro [SHIZAKI

and flush or low-rimmed on muri and slope offossae; some come up through warty tubercles
on sola. Larger pores equipped with celate sieve
plate rarely observed.
In internal view, outer margin rather narrowly
concave in front of mid-length of ventral margin,
and overpassed broadly by outline along dorsal
and ventral margins. Inner lamella wide along
anterior and posteroventral margins. Line of concrescence nearly coincides with inner margin.
Radial pore canals thick, widely spaced inclusters, diverge into two or three canals anteriorly in anterior margin, but simpler in posterior
and ventral margins. Eight canals discernible
in inner margin and 21 canals in outer margin ofanterior margin, five canals in posterior margin,
and 13 canals in ventral margin. Marginal extension of flange distinct along lower two-thirds ofanterior margin, which denticulate in well-preserved specimens. Posterior apparent opening
distinct at mid-height, whose posterior terminal
feebly denticulate. Selvage distinct along entire
extracardinal angle. List rather wide, parallel tothe inside of selvage.
Hinge entomodont. Median element in left
valve finely crenulate narrow bar, whose anterior
terminal becomes increasingly thicker andmore coarsely denticulate anteriorly. In rightvalve, anterior tooth obliquely elongate, andtrilobate, posterior tooth massive and smooth.

Small snap-knob observable at concavity ofventral margin of right valve. Muscle scars consistof a vertical row of four adductor scars. An
oblong scar inclined anteriorly in front of them.
Internal openings of normal pore canals rather
large, widely spaced.
Dimensions. -Figured specimens, left valve,sample G4 (IGPS 97804, PI. 32, Fig. 2) 0.56 mm
long and 0.32 mm high; right valve, sample L1(IGPS 97805, PI. 32, Figs. la-c), 0.54 mm longand 0.33 mm high; right valve, sample M1 (IGPS
97806, PI. 32, Fig. 5, PI. 35, Fig. 5), 0.54 mm
long and 0.30 mm high.
Remarks. -Only a few well preserved specimens are available for this study due to the factthat this species only occurred rarely from themost studied samples. This species resembles
Callistocythere undata Hanai (1957) in somerespects, but differs in that the former is basically characterized by regularly spaced distinct
vertical ridges. This species is easily distinguishedfrom Callistocythere alata Hanai (1957) in theabsence of posteroventral spines.
Occurrence. -Common only
content 61.71%, Mdrf> 3.99).

at L1 (mudFamily Hemicytheridae Puri, 1953
Subfamily Thaerocytherinae Hazel, 1967

Explanation of Plate 29
Figs. 1-4. Buntonia scorta Ishizaki, n. sp.
1. Lateral view:adult right valve (Paratype, IGPS 97786; Sample G5). x 120.
2. Lateral view, adult left valve (Paratype, IGPS 97785; Sample H2). x 120.
3. Internal view, adult left valve (Holotype, IGPS 97787; Sample G5). x 120.
4. Adult right valve (Paratype, IGPS 97788; Sample G5).
a. Internal view, x 120.
h. Part of Fig. 4a, showing details of central muscle scars. x 240.
Figs. 5-8. Buntonia u-carinata Ishizaki, n. sp.
5. Adult right valve (Holotype, IGPS 97789; Sample H3).
a. Lateral view, x 120.
h. Part of Fig. 5a, showing details of lateral surface, x 1,200.
6. Adult left valve (Paratype, IGPS 97790; Sample I1).
a. Lateral view, x 120.
h. Part of Fig. 6a, showing details of lateral surface, x 1,200.
7. Internal view, adult left valve (Paratype, IGPS 97792; Sample H3). x 120.
8. Internal view, adult right valve (Paratype, IGPS 97791; Sample H3). x 120.

[SHIZAKI: Ostracoda from the Ananai Formation

Plate 29

765. Ostracoda from the Ananai Formation

Genus Jugosocythereis Puri, 1957
Jugosocythereis? sp.

PI. 30, Figs. 1-3; PI. 35, Fig. 10
Description. --Carapace large, thick-shelled,
subtrapezoid with greatest length well below
mid-height and greatest height near anterior terminal of dorsal margin, and widest medially, but
abruptly deflated posterodorsally forming a flatrelief slope behind aU-shaped posterodorsal
ridge. Dorsal margin sinuous, rather narrowly
concave behind its anterior terminal, and broadly
arched near its posterior third. Ventral margin
nearly straight. Anterior margin somewhat depressed, ends below mid-height, meets dorsal
margin forming an obtuse cardinal angle, andmerges into ventral margin. Flange moderate inwidth along entire anterior margin. Posterior
margin truncated, its lower third distinctly
acuminate posteriorly, and its upper two-thirds
concave. It meets dorsal margin forming a rightangled cardinal angle, and the lower side of theacumination merges into ventral margin. Several
denticles or spines distinct around the acumination.
Surface ornamented with two marginal andmany other ridges. Outer marginal ridge continuous along almost entire margin, but very narrow
for the most part except along the inside of posterior margin, where it becomes much thicker
and runs parallel to the margin. Inner marginal
ridge distinct, runs along inside the outer marginal ridge from near anterior cardinal angle to posteroventral area via anterior and ventral margins.
It joins posteriorly with the outer marginal ridgeat posteroventral area and branches off upward
as two distinct vertical ridges at slightly anterior
points (branched-off vertical ridges join with theposterior part of aU-shaped posterodorsal ridge).
A distinct ridge starts anteriorly from subcentral
tubercle to anteroventral area, passing over inner
marginal ridge. Four subdued ridges extend posteriorly or posteroventrally from and above subcentral tubercle, and join to or fades before inner
marginal ridge. Two other ridges distinct in posterodorsal area united posteriorly with each147

other to form aU-shaped posterodorsal ridge. A
short ridge discernible within U-shaped posterodorsal ridge area. Short radial ridges distinct between outer and inner marginal ridges in anterior
marginal area. Several subsidiary ridges observable in front of subcentral tubercle. Most of theabove-mentioned ridges compose clear reticulation in association with very narrow traversing
ridges in between. Subcentral tubercle moderate
mid-length in adult specimen, but in submedianarea in immature specimens. Eye tubercle prominent near anterior cardinal angle. Intramural(secondary muri) pores, pores coming up throughwarty tubercles, and flush pores are simple,
rather large.
Internal openings of normal pore canals
simple, rather large, widely spaced. Central
muscle scars consist of a vertical row of four
adductor scars, each of which divided into two
as far as observed. Three scars in front of them.
Several scars above these scars. Examined immature specimens reveal that radial pore canals
simple, regularly spaced in anterior margin, butmore widely spaced anterodorsally. Forty-eightin anterior margin, eight in acuminate posterior
end, and 25 in posteroventral margin. Vestibule
well differentiated, attaining to about a third thewidth of inner lamella in anterior margin, butmuch narrower in posterior and posteroventral
margins.
Dimensions. -Figured specimens, complete
carapace, sample K9 (IGPS 97793, PI. 30, Fig.
1), 0.90 mm long and 0.50 mm high; immatureright valve, sample K2 (IGPS 97794, PI. 30, Figs.
3a, b, PI. 35, Fig. 10), 0.67 mm long and 0040
mm high; immature left valve, sample K2 (IGPS
97795, PI. 30, Figs. 2a-c) 0.69 mm long and 0041
mm high.
Remarks. -This form has yet to be examined
for its internal characters toward rigorous genericassignment, because only one complete adultcarapace is available for this study although agreat deal of specimens were found from 24 outof the 35 examined samples.
This form somewhat resembles Hermanites
posterocostatus Ishizaki (1966), but is distinguishable from the latter in that the former has

Kunihiro ISHIZAKI

148

an inner marginal ridge which runs verticallyalong inside the outer marginal ridge in the ante·rior marginal area and branches off upward as
two vertical ridges around a posterior fourth ofthe ventral margin.
Occurrence. -Abundant at K3 and K7 (mudcontent 58.6 and 54.1%, Mdl/> 4.05 and 3.99);
common at K1, K2, K4, K6, K8-11, H2-4, 11,
G3, G4, and G6 (measured mud content 33.050.1%, Mdl/> 3.67-3.87).
Family Trachyleberididae Sylvester·Bradley,
1948
Subfamily Buntoniinae Apostolescu, 1961
Genus Buntonia H. V. Howe, 1935

Buntonia parascorta n. sp.
PI. 28, Figs. 1·4; PI. 35, Fig. 1

Diagnosis. -Carapace moderate in size, thick.
shelled, sUbovate with truncated posterior mar.
gin. Six or seven short radial ridges bridge acrossfurrow along inside of anterior margin. Hinge
short, about half the length of carapace.
Description. -Carapace moderate in size, thick·shelled, subovate with greatest height just in
front of mid·length (at anterior cardinal angle) inlateral view, and slightly inflated around a hori.
zontal axis at mid·height except in a wide com.
pressed zone along anterior margin. Dorsal mar.

gin short, nearly straight, and abruptly descends
postward. Ventral margin broadly concave at
middle, or broadly arched. Anterior margin
broadly rounded, meets dorsal margin forming asomewhat distinct anterior cardinal angle, andmerges into ventral margin. Marginal extension offlange distinct along anterior margin from before
anterior cardinal angle to anteroventral area,
where a few marginal denticles often differ·entiated. Posterior margin truncated ventrally; itmeets dorsal margin forming a vague cardinalangle, and merges into ventral margin. Five or
more of marginal denticles, generated from anarrow marginal extension of flange, distinct on
well.preserved specimens.
Surface ornamented with marginal ridges
together with radial, horizontal, and corrugatedridges. Outer marginal ridge distinct, but short,and is confined to posterior margin. Inner mar·
ginal ridge, running from before posterior end of
dorsal margin to upper terminal of anterior
margin via ventral margin, prominent and wide
along anterior and ventral margins, and becomesnarrower along inside of outer marginal ridge.
Inside inner marginal ridge a broad furrow runs
along anterior and ventral margins, but it abrupt·
ly becomes much narrower along posterior
margin. Six or seven short radial ridges bridge
across this furrow along anterior margin; some ofthem extend up to anteromedian area. Dorsal
marginal ridge narrow, limited to a posterior half

Explanation of Plate 30
Figs. 1-3. Jugosocythereis? sp.
1. Lateral view, adult complete carapace (IGPS 97793; Sample K9). x 80.
2. Immature left valve (IGPS 97795; Sample K2).
a. Lateral view, x 80.
h. Part of Fig. 2a, showing details of external openings of normal pore canals, x 1,200.
c. Part of Fig. 2a, showing details of lateral surface, x 1,200.
3. Immature right valve (IGPS 97794; Sample K2).
a. Internal view, x 80.
h. Part of Fig. 3a, showing details of muscle scar arrangement, x 230.
Figs. 4, 5.
Callistocythere ananaiensis Ishizaki, n. sp.
4. Lateral view, adult right valve (Holotype, IGPS 97796; Sample HI). x 120.
5. Adult left valve (Paratype, IGPS 97797; Sample HI).
a. Lateral view, x 120.
h. Part of Fig. 5a, showing details of lateral surface, x 550.

[SHIZAKI: Ostracoda from the Ananai Formation

Plate 30

765. Ostracoda from the Ananai Formationof the margin. Lower horizontal ridge distinct
and long along inside the furrow from an anterior
third to near posterior end of ventral margin.
Upper horizontal ridge much shorter, confined toonly posterior part. Both the horizontal ridges
connected with each other by a U·shaped juncotion opening anteriorly. Several corrugatedridges, confined to posterodorsal area, narrowand irregular. Eye tubercle not distinct. Intra·
mural normal pores small, widely spaced. A few
rimmed somewhat larger pores observable. In
internal view, outer margin broadly concave near
mid-length and narrowly curved at posterior
terminal of ventral margin and overpassed
almost entirely by outline except for postero·ventral area in left valve and for near anteriorcardinal angle and posteroventral area in rightvalve.
Hinge holamphidont; median element short,being nearly half the length of carapace, strongly crooks ventrally at the junction of antero- andposteromedian elements. Anteromedian element
elongate, smooth, tooth-like process, and posteromedian element distinctly crenulate linear bar inleft valve. Anterior tooth prominent, bilobate,
protruded laterally, and posterior tooth massive,
inclined posteroventrally. Inner lamella moderately wide along anterior margin, an less wide
along antero- and posteroventral margins. Vestibule not differentiated. Radial pore canals somewhat sinuous, often bulbous at an anterior thirdof their length, bifurcate in some, and moderate
in number, but more widely spaced anterodorsally. Forty-four along anterior margin and 17
along posterior margin. Selvage, which bounds
anterior socket dorsally and posterior socket
posteriorly and runs along the upper side of
median element of hinge, distinct along entire
outer margin in left valve. A shallow furrow, an
accommodation to the selvage in left valve,
discernible along extracardinal outer margin
except for concavity near mid-length of ventral
margin in right valve. A somewhat elongate snapknob discernible below mid-length of ventral
margin in right valve. Muscle scars consist of avertical row of four very small and tightly spaced
adductor scars; anterior scars not distinct. A few

149

dorsal scars are in an arched line, starting fromabove adductor scars up to near anterior terminalof dorsal margin. Internal openings of normal
pore canals thick, widely spaced.
Type and dimensions. -Holotype, right valve,sample H2 (IGPS 97781, Pl. 28, Figs. la-c), 0.56mm long and 0.35 mm high; paratype, left valve,sample H2 (IGPS 97782, PI. 28, Figs. 2a, b), 0.54
mm long and 0.33 mm high; paratype, rightvalve, sample Kll (IGPS 97783, PI. 28, Fig. 4)
0.58 mm long and 0.34 mm high; paratype, left
valve, sample H2 (IGPS 97784, PI. 28, Fig. 1, PI.
35, Fig. 1),0.57 mm long and 0.38 mm high.
Type-locality. -About 80 m west of Ono,
Yasuda town, Aki County, Kochi Prefecture(sample H2).
Remarks. -This species is rather closely·
related to Buntonia hanaii Yajima (1978), but isdistinguishable from the latter in having distinct
horizontal ridges and short radial ridges which
bridge across the furrow along the inside of theanterior margin. Buntonia parascorta also resembles B. scorta n. sp. in many respects, but theformer has a larger non-reticulate carapace andtwo distinct horizontal ridges which are posteriorly connected with each other by aU-shaped
junction.
Occurrence. -In addition to the common
occurrence at the type locality, this species was
rarely found from Kll and G5.
Buntonia scorta n. sp.
Pi. 28, Figs. 5, 6; Pi. 29, Figs. 1-4; Pi. 35, Fig. 3

Buntonia sp. Ishizaki, 1981, p. 48, 49, pi. 9, fig.
11, pi. 10, figs. 4a, b, 5, pi. 15, fig. 9.

Diagnosis. -Carapace moderate to rather small,thick-shelled, sub ovate. Compressed peripheral
zone broad. Horizontal ridge distinct along
ventral margin. Hinge short, about half thelength of carapace.
Description. -Carapace moderate to rather
small, thick-shelled, and sub ovate in lateral view.
Compressed peripheral zone broad along theinside of outline except for posterodorsal area.
Dorsal margin short, rather narrowly arched, and150

Kunihiro [SHIZAKI

ends anteriorly near mid-length of carapace
where anteromedian element of hinge structure
is divided from posteromedian element. Ventral
margin broadly arched. Anterior margin symmetrically rounded, merges into dorsal andventral margins. Posterior margin more narrowly
rounded, merges into dorsal and ventral margins.
Marginal extension of flange discernible along
entire extracardinal outer margin. Several shortmarginal denticles, generated from a very narrowmarginal extension of flange, distinct alongposterior margin of well-preserved specimens.
Surface ornamented with reticulation except
for compressed peripheral zone. In addition,
marginal, horizontal, and corrugated ridges
distinct. Marginal ridge wide, continuous fromanterodorsal area to above mid-height of posterior margin via ventral margin, and forms awide compressed peripheral zone without distinct reticulation, which decreases in width postward. Horizontal ridge runs along ventral margin
from above anteroventral margin to a point
above posteroventral margin, and then turns andfades upward. Corrugated ridges particularly distinct in posterodorsal area, where they strengthen muri vertically. An anteriorly inclined depression distinct just below anterodorsal margin. Eye
tubercle not so distinct. External openings ofnormal pore canals moderate in size, flush, widely spaced. A few celate pores also observable on
apophyses.

In internal view, outer margin broadly concave near mid-length and narrowly curved at
posterior terminal of ventral margin, and widely
overpassed almost entirely by outline except for
posteroventral and posterodorsal areas in left
valve and for near anterior cardinal angle, in addition, in right valve. Hinge holamphidont. Medianelement short, being ~early half the length ofcarapace, sharply crooks ventrally at the junctionof antero- and posteromedian elements. Anteromedian element round, smooth, and tooth-likeprocess, and posteromedian bar narrow but somewhat thickens near its terminals, straight, anddistinctly crenulate in left valve. Anterior toothsmooth, and narrowly protruded laterally, andposterior tooth slightly incised ventrally in rightvalve.
Inner lamella moderately wide along anterior
margin, and less wide along antero- and posteroventral margins. Vestibule not differentiated.
Radial pore canals somewhat sinuous, often
bulbous at an anterior third to near anterior endof their length, bifurcate in some, andmoderate in number, but more widely spaced
anterodorsally: Forty-three along anterior margin
and 12 along posterior margin. Selvage, whichbounds anterior socket dorsally and posterior
socket posteriorly, distinct along entire extracardinal outer margin in left valve. Two lists
observable along anterior margin. A round snapknob discernible below mid-length of ventral

Explanation of Plate 31
Figs. 1-3. Callistocythere ananaiensis Ishizaki, n. sp.
1. Internal view, adult left valve (Paratype, IGPS 97799; Sample HI). x 120.
2. Internal view, adult right valve (Paratype, IGPS 97798; Sample HI). x 120.
3. Adult right valve (Holotype, IGPS 97796; Sample HI).
a. Part of lateral view, showing details of lateral surface, x 1,200.
h. Part of lateral view, showing details of external opening of normal pore canal, x 2,400.
Figs. 4-7. Callistocythere kattoi Ishizaki, n. sp.
4. Adult right valve (Paratype, IGPS 97801; Sample HI).
a. Lateral view, x 120.
h. Part of Fig. 4a, showing details of lateral surface, x 800.
c. Part of Fig. 4a, showing details of external openings of normal pore canals, x 800.
5. Lateral view, adult left valve (Holotype, IGPS 97800; Sample HI). x 120.
6. Internal view, adult left valve (Paratype, IGPS 97802; Sample HI). x 120.
7. Internal view, adult right valve (Paratype, IGPS 97803; Sample HI). x 120.

ISHIZAKI: Ostracoda from the Ananai Formation

Plate 31

765. Ostracoda from the Ananai Formation
margin in right valve. Muscle scars in subcentral
area consist of a vertical row of four very small
and tightly spaced adductor scars. Two small
scars in front of them fused to form a united Jshaped scar. Internal openings of normal pore
canals small and widely spaced, but a few ofthem distinctly thicker.
Type and dimensions. -Paratype, left valve,sample H2 (IGPS 97785, PI. 28, Fig. 5, PI. 29,
Fig. 2) 0.51 mm long and 0.35 mm high; paratype, right valve, sample G5 (lGPS 97786, PI.
28, Fig. 6, PI. 29, Fig. 1) 0.52 mm long and 0.33
mm high; holotype, left valve, sample G5 (lGPS
97787, PI. 29, Fig. 3, PI. 35, Fig. 3) 0.51 mm
long and 0.35 mm high; paratype, right valve,sample G5 (IGPS 97788, PI. 29, Figs. 4a, b) 0.51
mm long and 0.33 mm high.
Type-locality. -About 150 m west of Sempuku, Nahari town, Aki County, Kochi Prefecture (sample G5).
Remarks. -This species is closely related to
Buntonia parascorta n. sp. in many respects, but
is distinguishable from the latter in having a moreregular reticulation except in a broad compressed
peripheral zone, vague short radial ridges which
bridge across the anterior peripheral zone, andby lack of an upper horizontal ridge.
Occurrence. -Common at K6-8, H2, and G6(measured mud content 44.2-50.0%, Md!f> 3.843.99).

Buntonia u-carinata n. sp.
PI. 29, Figs. 5-8; PI. 35, Fig. 4?Ambocythere sp. Hu, 1978, p. 146, pI. 3, fig.
25, Figs. 19A, B.

Diagnosis. -Carapace moderate in size, thickshelled, suboblong with truncated posterior end.
Posterior half reticulate, ornamented with two
horizontal ridges which connect with each otherto form a U-shaped junction.
Description. -Carapace moderate in size, thickshelled, suboblong with greatest height at or
somewhat before mid-length in lateral view, andinflated around a horizontal axis at mid-height
except in compressed peripheral zone along ante-151

rior margin. Dorsal margin short, being confined
to posterior half of carapace, nearly straight orslightly arched, and gradually descends postward.
Ventral margin nearly straight or broadly arched.
Anterior margin symmetrically round, meets
dorsal margin forming a more or less discernible
cardinal angle at mid-length, and merges into
ventral margin; marginal extension of flange
discernible from an upper part of anterior margin
to anterior terminal of ventral margin. Posterior
margin ends below mid-height, narrowly round,and merges into dorsal and ventral margins inright valve, but it is more or less strongly truncated, meets dorsal margin forming a distinct
cardinal angle at posterior terminal of dorsal
margin (due to the wall bounding posterior
socket), and merges into ventral margin in left
valve; marginal extension of flange observable,from which several denticles are differentiatedalong a margin below cardinal angle in left valve.
Surface ornamentation with distinct reticulation is confined to a posterior half. Marginal
ridge of high relief rather narrow, but continuous, starting from upper terminal of anterior
margin to near mid-height of posterior margin
via ventral margin, and then fades upwards. A
deep furrow distinct along inside marginal ridge
except for near posterior end where reticulation
makes it intermittent. Two horizontal ridges,
confined to a posterior half, are more distinct
than marginal ridge, and are connected with eachother forming a U-shaped junction. Eye tubercle
not distinct. External openings of normal pore
canals flush, large or small, widely to moderately
spaced on ridges or elevated portions, but small,rather closely spaced in some sola.
In internal view, outer margin almost entirely
overpassed by outline except for posterior andnear anterior terminals of dorsal margin, slightly
concave near mid-length. It narrowly curves atposterior terminal of dorsal margin in left valve.
Hinge holamphidont; median element slightly
longer than half the length of carapace, crooks
ventrally near the junction of antero- and posteromedian elements. Anteromedian element rather
small, elongate, smooth, protruded laterally as atooth, and posteromedian element distinctly

152

Kunihiro ISHIZAKI

crenulate linear bar which thickens toward posterior tenninal in left .valve. Anterior toothprominent, protruded laterally, and posterior
tooth massive, somewhat larger than anterior
tooth, incised anteroventrally. Inner lamella
moderately wide along anterior margin, and lesswide along antero- and posteroventral margins.
Line of concrescence apparently coincides with
inner margin. Radial pore canals relatively thick,somewhat sinuous, bifurcate in some, bulbous inmany at or before an anterior third of theirlength, and relatively few in number, and more
widely spaced anterodorsally. Forty along anterior margin and 14 along posterior margin.
Selvage distinct along almost entire outer margin.
A distinct list runs along anterior margin. Muscle
scars in subcentral area consist of a vertical row
of four small and tightly placed adductor scars.
An oblong scar in front of them inclined anteriorly. A large and several small scars observable asdorsal scars. Internal openings of nonnal pore
canals thick, widely spaced.
Type and dimensions. -Holotype, right valve,sample H3 (IGPS 97789, PI. 29, Figs.5a, b) 0.53
mm long and 0.28 mm high; paratype, left valve,sample 11 (IGPS 97790, PI. 29, Figs. 6a, b) 0.52
mm long and 0.29 mm high; paratype, rightvalve, sample H3 (IGPS 97791, PI. 29, Fig. 8, PI.
35, Fig. 4) 0.54 mm long and 0.31 mm high;paratype, left valve, sample H3 (IGPS 97792, PI.
29, Fig. 7) 0.53 mm long and 0.30 mm high.
Type-locality. -At about 81 m west of Ono,
Yasuda town, Aki County,· Kochi Prefecture(sample H3).
Remarks. -This species is related to Buntonia
parascorta n. sp. in many respects, but is distinguishable from the latter in having a distinct
reticulation in the anterior half of carapace andby lack of distinct radial ridges which bridge
across a compressed peripheral zone along anterior margin. Buntonia u-carinata also resembles
Buntonia scorta n. sp. in some respects, but thefonner has two distinct horizontal ridges which
are connected with each other by aU-shaped
junction and by lack of a distinct reticulation in
the anterior half of carapace.
Occurrence. -Common at P2, L2-4, M1, H2,
H3, 11, and G5 (measured mud content 49.573.8%, Mdt/> 3.82-4.14).
Family Xestoleberididae Sars, 1928
Genus Xestoleberis Sars, 1866
Xestoleberis sp.

PI. 34, Figs. 1-3; PI. 35, Fig. 6
Xestoleberis sp. B Ishizaki, 1968, p. 42, pI. 6,
fig. 16.

Explanation of Plate 32
Figs. 1,2, 5. Callistocythere sp.
1. Adult right valve (IGPS 97805; Sample L1).
a. Lateral view, x 120.
b. Part of Fig. la, showing details of lateral surface, x 800.
c. Part of Fig. la, showing details of external opening of normal pore canal, x 800.
2. Lateral view, adult left valve (IGPS 97804; Sample G4). x 120.
5. Internal view, adult right valve (IGPS 97806; Sample M1). x 120.
Figs. 3, 4, 6, 7. Cytherella japonica Ishizaki, n. sp.
3. Immature right valve (Paratype, IGPS 97808; Sample H3).
a. Lateral view, x 80.
b. Part of Fig. 3a, showing details of lateral surface, x 1,600.
4. Adult left valve (Paratype, IGPS 97807; Sample K9).
a. Lateral view, x 80.
b. Part of Fig. 4a, showing details of external opening of normal pore canal, x 2,400.
6. Internal view, adult left valve (Holotype, IGPS 97809; Sample H3). x 80.
7. Internal view, adult right valve (Paratype, IGPS 97810; Sample K9). x 80.

!SHIZAKI: Ostracoda from the Ananai Formation

Plate 32

765. Ostracoda from the Ananai Formation
Description. -Carapace moderate in size, subtrapezoidal or subpentagonal with greatest heightslightly behind mid-length in lateral view, andwidest around just above a posterior third ofventral margin. Ventral absolutely flat. Dorsal
margin distinctly arched, more narrowly protruding slightly behind mid-length. Ventral margin
nearly straight. Anterior margin asymmetrical,
narrowly rounded well below mid-height, merges
into dorsal margin, and meets ventral marginforming a narrowly rounded corner. Posterior
margin truncated, ends slightly above posterior
terminal of ventral margin, meets dorsal marginforming a more or less distinct cardinal angle,
and ventral margin at rounded right angles.
Surface smooth entirely. Eye spots not observed. Sieve-plate pores with setose pores almost
flush, widely spaced.
Internally, outer margin broadly concaveslightly before mid-length of ventral margin, andits posteroventral area overpassed to a certain
extent by outline. Inner lamella moderate inwidth only in anteroventral area, where a narrow
but deep vestibule attains to about three-fourths
the width of inner lamella, and much subdued in
the remaining portion of extracardinal margin.
Radial pore canals simple and numerous inanteroventral and ventral margins, but more
widely spaced in anterior and posterior margins.
About forty canals in anterior to anteroventralarea, four in posterior margin, and 28 in ventral
margin. Selvage distinct along entire outermargin. Hinge merodont. Anterior tooth narrow,elongate, and crenulate, and posterior tooth
thicker, elongate, slightly arched, and polylobate,
and median groove finely crenulate in right valve.
Internal openings of normal pore canals simple,
rather large.
Dimensions. -Figured specimens, left valve,sample K4 (IGPS 97818, PI. 34, Fig. 3) 0.61mm long and 0.33 mm high; right valve, sample
K4 (IGPS 97819, PI. 34, Figs. la, b) 0.53 mm
long and 0.28 rom high; right valve, sample K4(IGPS 97820, PI. 34, Fig. 2, PI. 35, Fig. 6) 0.59mm long and 0.31 mm high.
Remarks. -This form is definitely conspecificwith Xestoleberis sp. B Ishizaki (1968) reported

153

from Uranouchi Bay, Kochi Prefecture, Japan,
but is still to be examined for its internal features
because only a few relatively well-preserved adultspecimens are studied in this work. Xestoleberis
suetsumuhana Yajima (1982) resembles thisform. It is, however, distinguished in that thelatter has an anterior vestibule much narrowly
confined to the ventral side and the longest axis
placed more ventrally.
Occurrence. -Common at P3, K3, K4, and K7(measured mud content 33.4-58.6%, Md<l> 3.774.05).
Acknowledgments
It is a great pleasure to thank Professor
Yokichi Takayanagi of the Institute of Geology
and Paleontology, Tohoku University, for hiskind provision of samples for this study, encouragement, and reading of this manuscript.
The author is deeply indebted to the authoritiesof the British Museum (Natural History), theHancock Museum, Newcastle-upon-Tyne, and Dr.
N. de B. Hornibrook of the New Zealand Geological Survey, all who kindly arranged for thewriter to examine materials under their care.
The works on which this study is based were
supported by the Grant-in-Aids for Co-operative
Research of the Ministry of Education, Science
and Culture of Japan (434042), which wasavailable during the period of 1979 through
1982.

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1-14.
Bold, W. A. van den (1950): Hemikrithe, a new
genus of Ostracoda from the Indopacific.

154

Kunihiro ISHIZAKI

Ann. Mag. Nat. Hist., ser. 12, vol. 3, p. 900904.
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ostracodes from the Chinshui Shale, Miaoli

Explanation of Plate 33
Figs. 1-4. Krithe hanaii Ishizaki, n. sp.
1. Adult right valve (Paratype, IGPS 97812; Sample K7).
a. Lateral view, x 80.
b. Part of Fig. la, showing details of lateral surface, x 1,200.
c. Part of Fig. la, showing details of external opening of normal pore canal, x 1,200.
2. Lateral view, adult left valve (Paratype, IGPS 97811; Sample K7), x 80.
3. Internal view, adult left valve (Holotype, IGPS 97813; Sample H2), x 80.
4. Internal view, adult right valve (Paratype, IGPS 97814; Sample K11), x 80.
Figs. 5, 6.
Bairdoppilata sp.
5. Adult left valve (IGPS 97816; Sample L3).
a. Lateral view, x 55.
b. Part of Fig. 5a, showing details of lateral surface, x 800.
c. Part of Fig. 5a, showing details of external openings of normal pore canals, x 800.
6. Lateral view, adult right valve (IGPS 97815; Sample L4), x 55.

ISHIZAKI: Ostracoda from the Ananai Formation

Plate 33

765. Ostracoda from the Ananai Formation
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155

ment of the Diluvium Furuya Mud basin,
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Kunihiro !SHIZAKI(Ostracoda) aus dem Pazifik. Senckenberg.
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Explanation of Plate 34
Figs. 1-3. Xestoleberis sp.
1. Adult right valve (IGPS 87819; Sample K4).
a. Lateral view, x 120.
b. Part of Fig. la, showing details of sieve-plate pore, x 3,500.
2. Inner view, adult right valve (IGPS 97820; Sample K4). x 120.
3. Lateral view, adult left valve (IGPS 87818; Sample K4). x 120.
Fig. 4. Bairdoppilata sp.
Inner view, adult right valve (IGPS 97817; Sample L1). x 55.
Figs. 5-8. Munseyella oborozukiyo Yajima, 1982.
5. Adult right valve (IGPS 97821; Sample P1).
a. Lateral view, x 160.
b. Part of Fig. 5a, showing details of lateral surface, x 550.
c. Part of Fig. 5a, showing details of external openings of normal pore canals, x 1,200.
6. Lateral view, adult left valve (IGPS 97822; Sample P1). x 160.
7. Inner view, adult left valve (IGPS 97824; Sample P1). x 160.
8. Inner view, adult right valve (IGPS 97823; Sample P1). x 160.

[SHIZAKI: Ostracoda from the Ananai Formation

Plate 34

765. Ostracoda from the Ananai Formation
foraminifera and Ostracoda in bottom sediments of the northwestern part of thesouthern Yellow Sea. Lab. Marine Micropal.,
Dept. Marine Geol., Tuny-Chi Univ., p. 1115, pIs. 1-18 (in Chinese).
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Univ., Jour., 1979 no. 2, p. 90-108, pIs. 1,
2 (in Chinese with English abstract).
- - , - - and Gao, J. (1980): A preliminary

157

study of foraminiferal and ostracod assemblages of the Yellow Sea. Papers on Marine
Micropaleontology, Peking, p. 84-100, pI.
11 (in Chinese with English abstract).
Yabe, H. (1918): Notes on Operculina-rock fromJapan, with remarks on "Nummulites" cumminigi Carpenter. Tohoku Imp. Univ., Sci.
Rep., 2nd ser. (Geol.) , vol. 4, no. 3, p. 105126,pl.17.
Yajima, M. (1978): Quaternary Ostracoda from
Kisarazu near Tokyo. Trans. Proc. Palaeont.
Soc. Japan, N. S., no. 112, p. 371-409, pIs.
49,50.
-(1982): Late Pleistocene Ostra:coda from theBoso Peninsula, Central Japan. In T. Hanai(ed.) Studies of Japanese Ostracoda, Univ.
Tokyo, Univ. Museum, Bull., no. 20, p.
141-227, pIs. 10-15.

~~KiffJl:fl'JlI (ggj;j!J) 0) JUf~!!l.-~G~- : IflHlI;til· (1953) iI~:fI;rL!!l.O)jjIf~I:'.ffl~ ,t.:,t 0)0) ? ~O) 35 ~*4i1' G.FOf~!!l.1t;:OH§tlli L.t.: • .:tn GO)~!{!'¥=Il9~ttO)*5*, J\:J1311 J: I) 42 ~79 f!1l0) fUf~!!l.f!1l~illltlJIJ L.., .:tn GO).itlli~~1f-i" 0
t t:., 7 ~f!1l (Buntonia parascorta,
B. scorta, B. u-carinata, Callistocythere ananaiensis, C. kattoi, Cytherella japonica,
Krithe hanaii) :to J: v: 4 *~~f!I!~~GJiII: L.t.:.
Jl:fI'J II 0) JtM!!l.~~H;t, *f.I3O)l:$~~9ItJ: I) vt:l1E¥Il1!l' ~n"(~ '0 t 0) 1:..Lt L.."( ~t,R"("(il'j7lj0)l:$~~9It0)1!~"f' Benson (1964) 0)1:/ r-:;t3J1.1$9It, *-,7.. r 7 ~ 7-f; ,7.."7.=.
791t, .=. '" -;;7:/ r9lt~0)~~~~ts), JK.,;;-rl'filiI'lWll: (c O:..:tO)?Hllc$) O)~#!c;Jl<
jiJj L.. t.:~Il~1f- L.. "( ~'o.
Bairdoppilata, Doratocythere, jugosocythereis? 0) 3 /il.t0)*f.I3l:$~~9It J: I) O).itilicc~~~"(O)¥Ilft"("~o.

:0 _

j;j!J

~

158

Kunihiro ISHIZAKI

Explanation of Plate 35
Inner view by transmitted light
Fig. 1. Buntonia parascorta Ishizaki, n. sp.
Adult left valve (Paratype, IGPS 97784; Sample H2). x 123.
Fig. 2. Callistocythere ananaiensis Ishizaki, n. sp.
Adult right valve (Paratype, IGPS 97798; Sample HI). x 123.
Fig. 3. Buntonia scorta Ishizaki, n. sp.
Adult left valve (Holotype, IGPS 97787; Sample G5). x 123.
Fig. 4. Buntonia u-carinata Ishizaki, n. sp.
Adult right valve (Paratype, IGPS 97791; Sample H3). x 123.
Fig. 5. Callistocythere sp.
Adult right valve (IGPS 97806; Sample Ml). x 124.
Fig. 6. Xestoleberis sp.
Adult right valve (IGPS 97820; Sample K4). x 124.
Fig. 7. Munseyella oborozukiyo Yajima, 1982.
Adult right valve (IGPS 97823; Sample PI). x 167.
Fig. 8. Callistocythere kattoi Ishizaki, n. sp.
Adult left valve (Paratype, IGPS 97802; Sample HI). x 121.
Fig. 9. Krithe hanaii Ishizaki, n. sp.
Adult left valve (Paratype, IGPS 97813; Sample H2). x 61.
Fig. 10. Jugosocythereis? sp.
Immature right valve (IGPS 97794; Sample K2). x 127.

ISHIZAKI: Ostracoda from the Ananai Formation

Plate 35

Trans. Proc. Palaeont. Soc. Japan, N. S., No. 131, pp. 159-167, September 30, 1983

766. OXYGEN AND CARBON ISOTOPIC COMPOSITION IN THE
SKELETON OF AN AHERMATYPIC SCLERACTINIAN CORAL ,DENDROPYLLIA JAPONICA Rehberg*
AKIOOMURA
Department of Earth Sciences, Faculty of Science,
Kanazawa UniversityeAbstract. The variation in oxygen isotope ratio SO/ 160) shows the periodicity within a given corallite of an ahermatypic scleractinian coral, Dendrophyllia
japonica Rehberg, which was collected at the depth of 140 m in the Toyama Bay,
Central Japan. The variation in 13C/I2c ratio, however, is little observed in the same
portion of the corallite. The annual growth rate of the corrallite in this area isestimated to be 23-24 mm, the distance from peak to peak in the periodicity,on the bases of the temperature dependence of the IS0/160 ratio in ahermatypiccoral skeletons and of the seasonal change in local sea water temperature.
The distal part of the same corallite denotes much lower IS0/160 and 13C/
12C ratios than those in the other parts. This observation suggests that metabolic
oxygen and carbon are vigorously incorporated into the skeleton at the front of
the growth of coral and that the proportion of skeletal CO~ - derived from metabolic
CO 2 to those from inorganic HC03" taken from sea water is apparently varied in
the process of skeletal calcification.

variations in the skeletal carbonate of corals
are temperature and zooxanthellar activity.
Moreover, they showed that the 0 180 value
versus temperature curves for various hermatypicscleractinian genera are parallel or nearly parallelto the isotopic paleotemperature scale determined by Epstein et al. (1953) and later modified by Craig (1965). In the case, the scleractinian curves are displaced toward more negativeoISO values. Such a temperature dependence of
0 180 value in hermatypic genera was lately
proved for Montastrea annularis from several
locations by Emiliani et al. (1978) and Fairbanks
and Dodge (1979). Weil et al. (1981) also substantiated the temperature dependence of coralskeletal 0 180 values by their careful experimentson two hermatypic coral species, Pocillopora
damicornis and Montipora verrucosa, which were
cultured under various controlled temperatureand light conditions. Meanwhile, carbon isotope
ratios (013C values) in the skeleton of hermatypic

Introductory Notes
Despite the widespread abundance in marine
environment, the skeletons of scleractinian corals
were not noted for a fairly long time with respect
to the oxygen and carbon isotopes after the workof Epstein et al. (1951), by the reason of theisotopic disequilibrium with the ambient sea
water. In the 1970's, studies on isotopic composition of scleractinian corals became active
little by little, and then some noteworth results
have been reported one after another.
Weber and Woodhead (1970, 1972a, 1972b)
and Weber (1973) examined the coelenterates
from many places in respect to the stable isotope
ratios of their skeletons. In a series of theirresearch, they reached a conclusion that themost important factors causing isotope ratio* Received Aug. 14, 1982; read Jan. 26, 1980 at
Tsukuba.
159

AkioOMURA

160

corals have been considered to change as a function of water depth (Weber et al., 1976; Fairbanks and Dodge, 1979), because l)l3C values
are chiefly controlled by the activity of thesymbiotic zooxanthellae which is associatedwith change in light intensity.
Developing the idea of Weber and Woodhead(1970), Goreau (1977) thought out a theoreticalmodel to explain oxygen and carbon fractionation in process of the calcification of hermatypiccorals, and then Erez (1978) verified experimentally the mechanism by which lighter carbon
and oxygen isotopes 2C and 16 0, respectively)
were selectively enriched into the skeleton ofhermatypic corals.
Deep-sea ahermatypic corals have been known
to be generally less depleted in 13C and 180 thanhermatypic corals and to be temperature dependent for l) 180 value of their carbonate skeletons (Weber, 1973). Emiliani et al. (1978) also
discussed the possibility of a small-sized solitarycoral Bathypsammill tintinnabulum as a temperature indicator, based on the fact that bothoxygen and carbon isotopes in the distal part ofcorallite which was fully matured approached
the eqUilibrium value with sea water.
The main aim of this study is to estimate theannual growth rate of an ahermatypic scleractinian coral Dendrophyllill japonica Rehberg byusing the cyclic variation of l) 180 value within agiven corallite. The change of l) 18 0 value mustbe periodical in the adequate part of the samecorallite growing in the region where sea watertemperature varies seasonally. Because little is
known about their growth rate, this attempt may
be significant to discuss the skeletal calcification
rates of ahermatypic corals without any symbiont, which are living over the entire temperature range of present-day ocean as comparedwith the relatively narrow temperature range ofhermatypes.

edredged at six locations in the Toyama Bay(Fig. 1). Most of all specimens were broken
branches and it was rarely the case that thebasal part was recovered. The bright yellowishcolored polyps were adhered originally to the
distal part of each corallite and their color
changed to dark brown after the collection,
while some organisms encrusted compactly tothe proximal part of branches.
It was the specimens collected at the locality
named St-26 that were used in the present study,
for the reason that the largest quantity of
Dendrophyllia corallum were dredged with a lotof other benthos. The St-26 was situated at thedepth of 140 m, about 10 km off Domi, Nanao
City, Ishikawa Prefecture. Only the portion of
the skeleton associated with the polyp was

17(120)'8(150)Fig. 1.

Index map showing the localities where
corallums were collectedduring the KT-75-6 Cruise of the R/V"Tansei-maru".
(Italic and parenthesized numbers represent
the station number and water depth, respectively. )Dendrophyllia
Material Studied
During the KT-75-6 Cruise of the R/V"Tansei-maru", an ahermatypic scleractiniancoral, Dendrophyllill japonica Rehberg, was

766. Oxygen and Carbon Isotopes in Corals

analyzed for the purpose of determining the
average isotopic composition of Dendrophyllia
skeleton and of comparing the average isotopic
composition between Dendrophyllia and shellsamples. The shell samples used here were two
species of molluscs, Pycnodonte musashiana(Y okoyama) and Chlamys iousseaumei Bavay,
and one of brachiopod, Terebratulina peculiaris
Hatai. These shell samples were entirely composed of calcite and were 16 mm in length and
15 mm in height, on the average.
A curved but the longest (about 19 cm)
Dendrophyllia branch was selected in order toexamine the variation in both oxygen andcarbon isotope ratios within a corallite. The
straight part was 6.3 cm in length from the tip.
Soft tissues were attached to the distal part up
to 14.2 mm in length. Some changes in diameterof the corallite could be observed but did notshow any systematic periodicity. This corallite
was elliptical in outline, and the maximum
diameter attained 21.5 mm. The septa were infive complete cycles, arranged in the hexameral
plan.
Experimental Methods
The main portion of septa was took awaywith a dentist's drill, after removal of polyp by
immersion in 10% sodium hypochlorite solution.
That is, only wall part of the corallite was used
for examining the variation in isotope ratios.
Because it was actually impossible to scrape
along the isochronal surface inside of septa andspecial care was exercised to avoid the contamination of younger skeletal materials to older
ones. The scraping of the specimen was carriedout by use of a flat-shaped and fine-grained me.
Both specimen and me were cleaned by blowing
the compressed air as often as one sample wascut off. Each sample was finally ground to about
250 mesh (621J. in diameter).
The powdered sample was roasted at 470°C
for 30 min. in an atmosphere of flowing helium.
Carbon dioxide was evolved under vacuum byreaction with 100% phosphoric acid and sub-161

sequently extracted and purified as described
before (Omura, 1977). Measurements weremade on powder ranging in weight from 15
through 20 mg. The sample gas was extracted
by standard techniques using trichloroethylene
and liquid nitrogen cooled traps. The standardized analytical procedure involved a reaction
time of about 15 hours and an extraction periodof 20 min.
Isotope ratios were determined with the
McKinney type mass spectrometer in whichsample and standard gases were alternately compared up to six times for 3 min. intervals. Isotope
ratios are reported in the widely used delta notation with respect to PDB standard CO 2 as:

8 180 = Rx - Rs x 1,000 Cloo, per mil)Rs

where R is the 180/ 16 0 (or 13C/ 12C for 8 13C)
ratio, and x and s refer to sample and standard,
respectively. The reproducibility of the measurement was less than 0.18 per mil for 8 180 andabout 0.11 per mil for 8 13 C. The isotopic composition of a working standard (CK-13) used inthis study has already established with respect
to PDB standard through interlaboratory calibration with H. A. Lowenstam and S. Epstein of
the California Institute of Technology and R. N.
Clayton of the Chicago University (Nakamichi
et al., 1969).

Results and Discussion(1) Composition of Dendrophyllia skeleton
versus shell samples.
The mean isotope ratios (8 180 and 8 13C
values) of Dendrophyllia skeleton and shellsamples are summarized in Table 1.
The mean 8 180 and 8 13C values of three
species of shell samples are +0.91 (±0.55) and+2.15 (±0.27) per mil, respectively. However,
8 values of shell samples examined here cannot
be used for the precise comparison with those ofDendrophyllia samples, because they are composed of the different mineral phase with eachAkioOMURA

162

Table 1.
Mean oxygen and carbon isotope ratios of Dendrophyllia
japonica Rehberg and three shell samples.

SampleDendrophyilia Japonlca- 2.48<0.79>10- 6.53(0.90>10

Terebratullna pecullarl s+ 0.67(0.33)5+ 1.95<0.21>5

Ch I amys Jousseaume I+ 0.70<0.63)5+ 2.42<0.08)5

Pyenodonte musashlana+ 1.36<0.30>5+ 2.10(0.22)5.

Format for data: mean delta value (standard deviation) numberof specimens analyzed.

-Ir-----.------.-----.------r-----.------.----~----~

-2
-3

-4
-5

1-----23.3mm --......--23.4 mm - - - - . I

-6
-7
-8

10

20

30

40

50

60

70

80mm

_Fig. 2. Variations in 8 180 and 8 13C values within a corallite of Dendrophyllia japonica Rehberg.
(Shaded part denotes the region where polyp was attached; the arrow shows the curvaturepoint of the corallite.)

766. Oxygen and Carbon Isotopes in Corals

other. It is possible to estimate the [) value of thearagonitic material in isotopic equilibrium withsea water. Such an aragonite is expected to givethe [) 180 value of +loS per mil relative to the
PDB standard, by using the equation of Horibeand Oba (1972). Accordingly, Dendrophyllia
skeleton is thought to be approximately 4.3 permil lower in [) 180 value than the aragonite inisotopic equilibrium with sea water. Dependingon the data of Weber and Woodhead (1972a), thedifference in [) 180 value between skeletons ofhermatypes and the aragonite in isotopic equiilibrium is not exceeding 3 per mil at a given temperature. Therefore, it can be conclusively said thatthe above observations support the strong "bital
effect" of ahermatypic corals, as mentioned byWeber (1973).
(2) Variations in [) 180 and [) 13C values within acorallite.
Variations in oxygen and carbon isotope
ratios within a given corallite are illustrated inFig. 2.
[) l3C value does not vary systematically andits variation is characterized by the limited
ranges, particularly in the straight-elongatedpart of the corallite. On the other hand, Fig. 2
denotes clearly the cyclio variation of [) 180
value in the corallite up to about 6 cm in lengthfrom the tip. The range of variation in [) 180
value is 1.17 to 1.91 per mil. The distance frompeak to peak in the periodicity is 23 to 24 mm.
If the salinity of the ambient sea waterchanged seasonally, apparent [) 180 and [) 13C
values alike should be influenced and show thesame pattern of their variations. The limited
range in variation of [) 13C value suggests thatthe chemistry of the sea water is little variedby the seasonal change in influx of fresh water.
If the variation in [) 180 value within the corallite
depends substantially on temperature curve isparallel or nearly parallel to the paleotemperature scale, as pointed out by Weber and Wood·head (1972a), the variation from 1.17 to 1.91
per mil in [) 180 value means that the seasonalchange in sea water temperature is approximately
5 to SoC at the sampling location. So far somedata at the location tell us about the change in163

temperature and salinity of the sea water throughthe year (Figs. 3 and 4). Such data seem tosupport that the temperature range of 5 to SoC
is not irrelevant as the seasonal variation in sea
water temperature even at the depth of 140 m
near the location where the samples analyzed
were collected.
For those reasons, the cyclic variation in[) 180 value is considered to be caused by theseasonal change of sea water temperature. In
other words, the distance from peak to peakseen in the periodicity is regarded as an annual
growth rate of Dendrophyllia japonica Rehberg.
The Dendrophyllia specimell used here was abroken branch, and hence it is quite hard toinfer what part in a dendroid corallum was
examined. It may, however, be said that the137"£

Fig. 3. Map showing some locations where
fixed point observation is carried out for
temperature and salinity of sea water by the
Fisheries Experiment Station of Toyama
Prefecture.
(Small black circles show the localities
where Dendrophyllia corallums were foundto inhabit at present.)Akio OMURA

164oTemperature
5

10

15

Salinity
25

3030

31

32

(%0)
33

34

35

+----~r--*-------_rr_--IO~--------TIHr--------.r.r-------15----------------~~--~~~+-------~~-------.~---------10G---------------~---1~~1+----fJf~------~-----------------+5O----------------------+~~~~

,,
,
,

,,
,
,,

,,
,
,

Depth (m)Fig. 4. The range of variation in temperature and salinity of sea water in the Toyama Bay.
(Thick dotted lines are drawn on fifty data at twelve locations from points A to L, from
April, 1953 through March, 1958: while thin solid and dotted lines on ten data from
November, 1978 through November, 1979, at twelve locations and point H, respectively.)
partial annual growth rate of Dendrophyllia
corallum attains 23 to 24 mm at this place. It
has often been said that growth rates of ahermatypic corals are much lower than hermatypes.
Because they do not have a favorable influence
upon the symbiotic zooxanthellae in theircalcification process. Further elucidation on thecyclic variation in [) 180 value will require moredetail observations. The growth rate of Dendrophyllia should be reconfirmed with a radiochemical technique by use of short-lived radioactive isotopes.
(3) Oxygen and carbon isotope ratios at the tipof a corallite.
Another interesting result was obtained in thevariation of oxygen and carbon isotope ratios

within a corallite. It is the low [) 180 and [) l3C
values observed at the tip of the corallite (Fig. 2).
In order to make sure whether such an extremely
low [) value is a characteristic common to all ofDendrophyllia corallite, only the wall part ofthree portions in a corallite was taken out fromthe other four corallite specimens as shown in
Fig. 5 and were examined for isotopic composition.
As a result, it is clear that all of the examinedcorallite show the same pattern without exception (Table 2). Because metabolic carbon is some
12 to 17 per mil lighter and metabolic oxygen issome 10 per mil ligher than those derived from
HC03" in sea water (Weber and Woodhead, 1970;
Land et aZ., 1975; Goreau, 1977; Emiliani et aZ.,

766. Oxygen and Carbon Isotopes in Corals

1978), it is very likely that metabolic carbon
and oxygen are vigorously incorporated into theskeleton which is secreted at the front of growth .
That is, the proportion of skeletal eo~ - derived
from metabolic CO 2 to that from inorganic
HC0 3 taken from sea water seems to vary in
the process of the skeletal calcification byhermatypic scleractinian coral. Such an apparent
variation in isotopic composition is summarized
in Fig. 6. In the case of Dendrophyllia skeletons,
it does never approach the value in isotopic
equilibrium with sea water, as shown for asmall-sized solitary coral Bathypsammia tintinnabulum by Emiliani et al. (1978) . These facts
is suggestive the followings: (1) Dendrophyllia
grow infinitely at the same growth rate if circumstances permit, whereas ahermatypic simple
corals like Bathypsammia cannot exceed certain
limit in size : (2) The higher 0 values in a corallite
except the tip may be resulted from reformationof the isotopic composition due to the secondary
thickenning or the secondary deformation offine skeletal structure during the life time ofscleractinian coral as observed in rugosa by Kato
(1963).

•

Fig. 5. Simplified sketch of Dendrophyllia
specimen showing three portions to examine
the variation in 0 18 0 and 0 l3e values withina corallite.
(Shaded part and black arrow represent thelimit of adherent polyp and growth direc·
tion, respectively.)

No .

o18

0pDB

c

b

a

Cora ll ite

o13

CpDB

165

o18

0pDB

o1 3

CpDB

o18

0pDB

o13

CpDB

1

- 6,94- 8,35- 3, 13- 7,00- 2,81- 7,382- 7, 45- 8,63- / ,48- 7,10- 2, 8LI- 7,373- 6,04- 8,06- 3,00- 6,18- 4,25- 5,824- 6,06- 7,81- 3,31- 5.74- 3,53- 6,205- 4,66- 8,79- 3,63- 7,33- 3,43- 7, 04

Mean de lt ava l ue- 6,23- 8,36- 3, 11- 6,67- 3,37- 6.76

S t anda r d
de v ia ti on(±1. 06)(±0 ,41)(±0, 42)(±0 ,68)(±0, 59)(±0 ,7l)

0 18 0 and 0 l3e values in different three portions within
Table 2.
the same corallite.
(See Fig. 5 for the portion analyzed.)AkioOMURA

166

+2 ~

8180PDB (%0)
-12

-10

-8

-6

-4

-2

+2

"Tansei-maru" of the Ocean Research Institute,
University of Tokyo, for collecting the samples
and to members of the Fisheries Experiment
Station of Toyama Prefecture for their permission to cite the data on temperature andsalinity of sea water in the Toyma Bay.

-2
References Cited

-4

~

*

-6
-8
-10
-12
-14 -0
~

M

-16

aJ
0
Il.

U

!<)

-18 60Fig. 6. l) 180 versus l) 13C diagram of the samples
examined in this study.
(B and C show mean l) values of bulk
Dendrophyllia skeleton. and shell samples,
respectively; a, band c, mean l) values ofthree portions illustrated in Fig. 5; M, l)value of metabolic carbon and oxygen incoral skeleton, mentioned by Weber andWoodhead, 1970; Land etal., 1975; Goreau,
1977; and Emiliani etal., 1978.)Acknowledgments
I wish to thank Prof. K. Konishi of the
Department of Earth Sciences, Faculty of
Science, Kanazawa University, for his continuous
encouragement throughout this study. Coraland shell samples used in this work were identified by Drs. K. Mori and K. Ogasawara of theInstitute of Geology and Paleontology, Facultyof Science, Tohoku University. My thanks arealso due to the KT-75-6 crew of the R/V

Craig, H. (1965): The measurement of oxygenisotope paleotemperature. In Tongiorgi, E.
(ed.): Stable Isotopes in Oceanographic
Studies and Paleotemperatures. p. 161182, Spoleto.
Emiliani, C., Hudson, J. H., Shinn, E. A. andGeorge, R. Y. (1978): Oxygen and carbon
isotopic growth record in a reef coral fromthe Florida Keys and deep-sea coral from
Blake Plateau. Science, vol. 202, p. 627629.
Epstein, S., Buchsbaum, R., Lowenstam, H. andUrey, H. C. (1951): Carbonate-water isotopic temperature scale. Bull. Geol. Soc.
A mer. , vol. 62, p. 417-426.
- - , - - , - - and - - (1953): Revisedcarbonate-water isotopic temperature scale.
Bull. Geol. Soc. Amer., vol. 64, p. 13151326.
Erez, J. (1978): Vital effect on stable-isotope
composition seen in foraminifera and coralskeletons. Nature, vol. 273, p. 199-202.
Fairbanks, R. G. and Dodge, R. E. (1979):
Annual periodicity of the 180 / 160 and13c/ 12c ratios in the coral Montastrea
annularis. Geochim. Cosmochim. Acta, vol.
43, p. 1009-1020.
Goreau, T. J. (1977): Carbon metabolism incalcifying and photosynthetic organism:
theoretical models based on stable isotope
data. Proc. 3rd Int. Coral Reef Symp., vol.
2, p. 395-40l.
Horibe, Y. and Oba, T. (1972): Temperaturescales of aragonite-water and calcite-water
systems. Fossils, nos. 23/24, p. 69-79.
(in Japanese with English abstract)
Kato, M. (1963): Fine skeletal structures inrugosa. Jour. Fac. Sci. Hokkaido Univ., Ser.
4, (Geol. & MineraL), vol. 11, p. 571-630.
Land, L. S., Lang, J. C. and Smith, B. N. (1975):
Preliminary observations on the carbon

766. Oxygen and Carbon Isotopes in Corals
isotopic composition of some reef coraltissues and symbiotic zooxanthellae. Limnol.
Oceanogr., vol. 20, p. 283-287.
Nakamichi, 0., Konishi, K. and Sakai, H. (1969):
On the isotopic analyses of oxygen andcarbon of marine biogenic carbonates suchas corals and pelecypods. Mass Spectro'
scopy, vol. 17, p. 500-508. (in Japanesewith English abstract)
Omura, A. (1976): On the measurement ofoxygen and carbon isotope ratios of biogenic
carbonates. Bull. Japan Sea Res. [nst.,
Kanazawa Univ., no. 8, p. 15-25. (in Japanese with English abstract)
Weber, J. N. and Woodhead, M. J. (1970):
Carbon and oxygen isotope fractionation in
the skeletal carbonates of reef-building
corals. Chem. Geol., vol. 6, p. 93-117.
- - a n d - - - (1972a): Temperature dependence of oxygen-18 concentration in reef
coral carbonates. Jour. Geophys. Res., vol.

167

77, p. 463-473.
--and ---(1972b): Stable isotope ratio
variations in non-scleractinian coelenterate
carbonates as a function of temperature.
Mar. Bioi., vol. 15, p. 293-297.
--(1973): Deep-sea ahermatypic scleractiniancorals: isotopic composition of the skeleton.
Deep-Sea Res. , vol. 20, p. 901-909.
- - , Deines, P., Weber, P. H. and Baker, P. A.
(1976): Depth related changes in the i3CI
12C ratio of skeletal carbonate deposited by
the Caribbean reef-frame building coral
Montastrea annularis: further implications ofa model for stable isotope fractionation byscleractinian corals. Geochim. Cosmochim.
Acta, vol. 40, p. 31-39.
Weils, S. M., Buddmeier, R. W., Smith, S. V. andKroopnik, P. M. (1981): The stable isotopic
composition of coral skeletons: control byenvironmenta; variables. Geochim. Cosmochim. Acta, vol. 45, p. 1147-1153.

3fJl!ili!¥.i1:-<t :/:::l Dendrophyllia japonica Rehberg 1tm-*0)~~ • ~~(l:ij{itf*mnX;: :fj
10 km· 7.Ki'?Ii 140 m 0):11!V#UI'1? r v '" y ~.hf,:,3fJl!iIi'-\i1:-<t:/ ::l'O)-fiI!
Dendrophyllia japonica Rehberg ll'm-*O)~~. ~~(l:ij{it{*!t (lsOpoO· 13C/12C) a-;;j<bbf.:. • .:to)*tli*, ~~(l:ij{itf*.ltO)~iIJ;?:'lc/vc'J!I?.htJ:~'o)lc..%tL, (l:ij- corallite O)nX;JJt1J[RJlc..fd"'? -C~~(l:ij{itf*!tO)RilWlEt:1~liIJ;?\~ 1?;?'lc..tJ: -:".:.. al80 {iiiO)~liIJrtm. 1.2-1.9%0 -e,
RilWli1:IU,.. I?.h;o -* ~ - ? r..'O)I€IIlIHi 23-24 mm -r:Jo"'? f.:.. ;: 0);: eli, 3fJl!ili!¥.i1:-<t:/ ::l'1t
m-4rO)M~(l:ij{itf*j:tO)iffi\Ji:{MH'.u, I?, ~,\'l!,~mlc..;I'-oft ;o7.Km0)2f;~~Nta-ff-i'" c ~.:t I?.h,
RilWli1:IU",I?.hf.:.-*~· - ? r..'O)I€~;?' 1?~~:l1!!ftilIO)(l:ijf!l!:O)-<t :/ :fO)nX;JJt$;?\ 20 mm/yr J;J.
J:lc..jli'";O c *tlimfli-r:~;o.
JII~'i'd::;Jt!:nfi3wJl[1Jk0

if.:., corallite O)J1lJ\:;!t,Iijt!f\lc..;I'-oft;oM~· ~~(l:ij{itf*.lt;?:c tlc..J:~GO)RilWli1:Ic...7",I?.hf.:.
{I& ~, Ii {if!a-ff-i'";: c ;?\Ij)JI?;?'lc..fJ: "'? f.:.. ;: mli:~;?' I?, c Ic..nX;;/lto)
J&iltr~ -r:-<t:/ ::l'IllII:gO)~~{'Fffl-r:{'FI?.h;o, ~ 'hl1>;o metabolic tJ:M~;I'-o J: V' ~~;?\ ~;?'lvlc..
J&jbi.h-C~';o;: c, if.:.-<t:/ ::l'1tm-O):fjl9({t~f!i!-r:, i!J}"~.h;oM~· ~~O)?~, w7.K4rO).m:~~ -< ;;j-:/ (HCO , ) m*O) to) c metabolic tJ: t 0) c O)trJ~;?\~fti'";o J: ? 1':::',\!I,h.h;o.
~liIJr\l a-;: ;(. -C, ~ L<<*H ~ mTrans. Proc. Palaeont. Soc. Japan, N. S., No. 131, pp. 168-176, pIs. 36, 37, September 30, 1983

767. LOWER TRIASSIC RADIOLARIA FROM THE
KANTO MOUNTAINS, CENTRAL JAPANPART 1: PALAEOSCENIDIIDAE*
KATSUO SASHIDA
Institute of Geoscience, The University of Tsukuba, Ibaraki 305

Abstract. Abundant and well-preserved Lower Triassic Radiolaria occurs fromthe Ogamata Formation, Kanto Mountains, Central Japan. This radiolarian assemblage contains Palaeoscenidiidae and many other spumellaria. Three genera and fivespecies of Palaeoscenidiidae were discriminated from the chert beds intercalated inthis formation. This spicular radiolarian assemblage is quite similar to that of
Paleozoic, and is very important to investigate the relationship between Paleozoic
and Mesozoic spicular Radiolaria. In this paper, I described the following fivespecies of Palaeoscenidiidae; Archaeosemantis venusta Sashida, n. sp., Archaeoseman tis sp., Parentactinia nakatsugawaensis Sashida, n. sp., Archaeothamnulus
ramosus Sashida, n. sp., and Archaeothamnulus? sp.

important to investigate the relationship between Paleozoic and Middle to Upper Mesozoic
radiolarian assemblages.
Based on many thin sections, Fujimoto(1933) discriminated two types of radiolarianassemblage, "Paleozoic-type" and "Mesozoictype" in chert formations distributed in the
Kanto Mountains and brought the "Argument ofRadiolaria" in Japan. However, since then, nocomprehensive study of radiolarian fossils ofchert formations has been made in the Kanto
Mountains. I have been studying the Mesozoic
and Paleozoic Radiolaria from the Kanto Mountains, and the present study deals with theLower Triassic Palaeoscenidiidae from chert
beds embedded in the Ogamata Formation
distributed in Okuchichibu.
I will express my sincere thanks to Professor
Hisayoshi Igo of the University of Tsukuba forhis continuous guidance in various ways andcritical reading of this manuscript. I am also
very much indebted to Professor Tadashi Satoand Dr. Shigeru Takizawa of the University

Introduction and Acknowledgments
Since the method of individual separation by
the acid treatment was established, our knowledge of the Triassic radiolarian fauna has been
accumulated by Kozur and Mostler (1972,
1978, 1979, 1981), Wever et al. (1979), Pessagno
et al. (1979), Dumitrica (1978a, b, 1982) andDumitrica et al. (1980) etc. Also, in Japan,
Nakaseko and Nishimura (1979) clarified a partof the Upper Triassic radiolarian fauna withthe detailed description. Moreover, biostratigraphical and paleontological studies of Triassic
radiolarians have been worked out by Yao et al.
(1982), Matsuda and Isozaki (1982), Mizutani
and Koike (1982) and others. According tothese contributions, the Triassic radiolarianbiostratigraphy and the zonation based on the
short ranged genera and species will be possible
to establish. The Triassic Radiolaria is very

* Received August 19, 1982; revised manuscript
received July 2, 1983.
168

767. Lower Triassic Palaeoscenidiidae from Kanto

169

of Tsukuba and Dr. Hisaharu Igo of Tokyo
Gakugei University for their encouragementand discussion in this work.
Geological Setting
The Lower Triassic Radiolaria was discriminated from the Ogamata Formation typically
exposed in the upper reaches of the Nakatsu
River in Saitama Prefecture (Text-fig. 1). The
geology of this area was summarized by Fujimoto et al. (1950), Fujimoto et a1. (1957) andIshii (1962). Recently, Ishii and Matsukawa(1980) restudied the stratigraphy and geologic
structure of this formation. However, Sato et al.
(1981), Sashida et al. (1982) discriminatedJurassic Radiolaria from the shale beds of thisformation and discussed the necessity of revision of stratigraphy and geologic structure.
The following stratigraphic units are recognizedin the Ogamata Formation, near the type section,
in descending order (Text-fig. 2):
7: Medium- to fine-grained sandstone; including volcanic breccia and alternation ofsandstone and mudstone - more than 30
meters thick.
6: Fine-grained sandstone; intercalating shalein the lower part and conglomerate withpebbles of various kinds of sedimentary
origin and basic rocks in the upper part about 100 meters thick.
5: Shale; including sandstone blocks ofabout three meters in maximum diameter- about 15 meters thick.
4: Chert; - about 60 meters thick.
3: Medium- to fine-grained sandstone; frequently including shale beds in the lower
and upper parts - about 20 meters thick.
2: Black shale; with sandstone blocks of 10
meters in diameter and discontinuouschert beds - about 20 meters thick.
1: Fine-grained sandstone; with intercalationof shale beds in the lower and middle
parts - 40 to 50 meters thick.
The Lower Triassic conodont, Neospathodussp., and the present radiolarian fauna occur fromlower chert beds of unit 2. This chert is usually

o

100km
1........1.....

0
'

,

SOOm
!

!

!

!

Text-fig. 1: Map showing the locality of theLower Triassic Radiolarians.

dark gray to black and interbedded with
tuffaceous films. The Upper Triassic conodonts,
Epigondolella postera and others and also wellpreserved radiolarians were discriminated fromthe upper chert beds of unit 4. Jurassic Radiolaria was obtained from all of shaly facies of thisformation.
Note on the Family Palaeoscenidiidae
Deflandre (1953) first introduced the spicularRadiolaria with four basal spines under the nameof Palaeoscenidium from the Lower Carboniferous deposits of Montagne Noire, France. Subsequently, Radiolaria with the same basal skeletons has been reported from the Upper Devonianof the Ohio Shale (Foreman, 1963) and South
Ural (Nazarov, 1975), and from the Silurian ofCornwallis Islands (Holdsworth, 1977). On theother hand, Dumitrica (1978b) reported the
spicular Radiolaria with four basal spines which
resembles Paleozoic Palaeoscenidiidae from theLower Ladinian of Italy and Rumania. Dumitrica
proposed the Subfamily Pentactinocarpinae toKatsuo SASHIDA

170

--0

..........

oJurassic RadiolariaxUpper Triass ic Rad.

le:

Lower Triassic Rad.

It. At. Ivolcanic breccia.......••

40m••.•..•.••••....•~~~.~::"-

0--0. .....cJ.-:.

k.:j Sandstone

T ~:::~,om"'"

10 ~Chert

Text-fig. 2: Generalized columnar section of
the Ogamata Formation, near the typesection.

the Triassic Palaeoscenidiidae that has four basal
spines and one apical spine, and the spumellarian skeleton was covered by globular corticalshell. Moreover, he introduced a new genus
Parentactinia to the Family Entactiniidae hav·
ing similar basal skeletons to Palaeoscenidium,but this genus shows bar-centered spine andhas globular shell connected with basal spine.
Recently, Dumitrica (1982) described many
Middle Triassic spicular radiolarians, some ofwhich he had included in Palaeoscenidiidae
and Entactiniidae from the same samples. He
discussed possible relationship among theseradiolarians and some Paleozoic and Cenozoic
taxa.
Furutani (1982,1983) discussed the construc·tion and phylogeny of Paleozoic and Mesozoic
Palaeoscenidiidae. According to his study,
Palaeoscenidiidae is composed of Palaeoscenidiinae and' Pentactinocarpinae. Palaeoscenidiinae is characterized by having the skeleton of two to four apical spines and four basal
spines with median bar. On the other hand,Pentactinocarpinae consists of one apical spineand four basal spines. He suggested that
Pentactinocarpinae was derived from Palaeoscenidiinae by extinction of three minor apicalspines, and discriminated seven genera in Palaeoscenidiinae and five genera in Pentactinocarpinae.
Takemura and Nakaseko (1982a, b) investigated
the skeleton of the Jurassic palaeoscenidiidsfrom manganese ore deposits in the Mino Belt,
Central Japan. They distinguished two types of
Palaeoscenidiidae belonging to Nassellaria, anddiscussed the relationship between the Paleozoic
and Jurassic palaeoscenidiids. Moreover, they
pointed out the revision of definition of the
Family Palaeoscenidiidae.
Lower Triassic Palaeoscenidiidae from the
Kanto Mountains is usually well-preserved andabundantly occurs. Three genera and five speciesof
Palaeoscenidiidae
werediscriminated.
Archaeosemantis venusta Sashida, n. sp. basicallyconsists of four basal spines and four apicalspines (Text-fig. 3), and this species resembles
closely Palaeoscenidium cladophorum describedby Deflandre (1953), Foreman (1963) andNazarov (1975). It is also similar to Archaeosemantis pterostphanus Dumitrica (1978b) andArchaeosemantis cristianensis Dumitrica (1982)
that have peculiar morphology and broad variations. Parentactinia nakatsugawaensis Sashida,n. sp. having four, long straight basal spinesand basket-like shell, is comparable to Parentactinia with palaeosceniid skeletons as shownin Text-fig. 5. However, this species is easily
distinguishable from Parentactinia of Dumitrica
in having long and straight basal spines that do
not show eccentric feature. The ill-preserved
specimens without shell of this species (PI. 2,

767. Lower Trillssic Palaeoscenidiidae from Kanto

F,igs. 2, 6, 7) are quite similar to Paleozoic
Radiolaria, Bissylentactinia rudicula Nazarov
and Haplentactinill rhinophusa Foreman. Moreover, Middle Triassic spicular Radiolaria
Palhindeolithus paululus, Tandarnill arachnoconcha and Tandarnia recoarense which were
described by Dumitrica (1982), resemble illpreserved specimens of Parentactinia nakatsugawaensis. Archaeothamnulus ramosus Sashida,n. sp. resembles Archaeothamnulus verticillatus
introduced by Dumitrica (1978b, 1982), but
usually its preservation is not complete.

Systematic Description
Subclass Radiolaria MUller, 1858
Order Polycystina Ehrenberg, 1838,
emend. Riedel, 1967
Suborder Spumellaria Ehrenberg, 1875
Family Palaeosenidiidae Riedel, 1967,
emend. Holdsworth, 1977
Genus Archaeosemantis Dumitrica, 1978
Archaeosemantis venusta Sashida, n. sp.

PI. 36, Figs. 1-9
Diagnosis. -Spicular skeleton with commonly
six to eight stout spines arising from ends of very
short median bar. Three or four of them are
longer, and other spines commonly shorter andstraight.
Description.-Commonly, four, long, delicate,rod·like basal spines and four, rod-like tapering
apical spines. The basal spines with rugged
external surface, divergent and curved inward
on a half, and distally tapering. Each of thebasal spines forms an angle of 55-60 degrees
with its neighbours. The divergent apical spines
are generally short, about a third to a fourthof the basal spines, and some of them gently
curved downwardly.
Dimensions. -Length of basal spines 115-200
microns, apical spines 25-75 microns (generally
30-70 microns), based on nine illustrated
specimens.

171

Remarks. -The present species resembles
Palaeoscenidium cladophorum originally described from Montagne Noire (Deflandre, 1953)
Ohio Shale (Foreman, 1963), and South Ural
(Nazarov, 1975). However, the former species
is distinguished from the latter by having straightbasal spines, with numerous spinules approximately at right angles to the spine. Moreover,
Palaeoscenidium cladophorum described by
Foreman, has lamellar quadrangular cup.
Dumitrica (1982) introduced Archaeosemantis
cristianensis from the Lower Ladinian of theBuchenstein Limestone of Italy. His two illustrated specimens (pI. 3, fig. 11, pI. 7, fig. 3) ofthis species rather resemble those of Archaeosemantis venusta. However, the former species
is easily distinguishable from the latter by having
two laterally directed apical spines and the basal
spines with spinules. Dumitrica (1982) also
described Archaeosemantis longivirga from thesame limestone. This species has four apicaland basal spines. However, it is distinguishable
from Archaeosemantis venusta by rather long
median bar and thorny spines.
The species name is from Latin, venustus,
beautiful.
Reg. nos. !GUT 5800 (Holotype), 5801-5808(Paratypes) .
Archaeosemantis sp.

PI. 36, Fig. 10
Description. -Four to five sturdy basal spinesand one to two tapering apical spines. The basal
spines with the remainder of numerous thorny
spinules, straight, divergent, and tapering. Eachof basal spines forms an angle of 30-70 degrees.
The apical spines shorter than one half to one
third of the basal spines, rod-like, and haverugged surface.
Dimensions.-Basal spines 100-120 microns,
and apical spines 60 microns based on illustrated
specimen.
Remarks. -Two specimens are obtained. The
present species resembles Archaeosemantis
venusta in having similar basal skeletons. However, it is distinguishable from the latter by

Katsuo SASHIDA

172

Text-fig. 4: Archaeosemantis sp. (scale
microns).Text-fig.3: Archaeosemantis venusta Sashida,.
n. sp. (scale = 25 microns)
having stout straight basal spines with remaindersof spinules. The basal skeleton of this species issimilar to Palhindeolithus pulcher reported byDeflandre (1973) from Montagne Noire, but
it differs from the latter in the number andsurface feature of the basal spines.
Reg. no. !GUT 5815.
GenusParentactinia Dumitrica, 1978
Parentactinia nakatsugawaensis Sashida, n. sp.

PI. 37, Figs. 1-9
Diagnosis. -Generally, spicule consisting of ashort median bar and eight stout spines, of whichfour spines are long and constitute base of an
incomplete single globular shell.
Description. -Four apical spines conical, obliquely directed, two of them rather long, rodlike, tapering and two others short. Four basal
spines cylindrical, long, stout, straight anddivergent. They connected with a rather loose
hemispheric shell having irregular shaped pores

50

resulted by intersection of bars with various
angle. Four stout spinules approximately atright angles to the basal spines, connected withthese bars and sustains this hemispheric shell.
The shell is not complete in apical region. The
basal spines seem to be not covered by shell
but remains as ridges.
Dimensions. -Basal spines 165-225 microns,
long apical spines 80-115 microns and shortapical spines 25-50 microns based on 9 specimens.
Remarks. -The present speCies abundantly
occurs, however, the well-preserved specimens
with shell are rare. The basal skeleton of thisspecies as shown in Text-fig. 5, has palaeonscenidiid affinities (Furutani, 1982), and isrelated to Parentactinia of Dumitrica (1978b).
This species resembles Parentactinia pugnax
described by Dumitrica (1978b). Especially
his illustrated specimen (pI. 4, fig. 5) is quite
similar to Parentactinia nakatsugawaensis.
However, Parentactinia nakatsugawaensis haslong straight basal spines and more incomplete
shell compared with Parentactinia pugnax.
The basal skeletons without hemispheric shell
also resemble. Paleozoic spicular Radiolaria,
such as Haplentactinia rhinophyusa Foreman,
Bissylentactinia rudicula Nazarov and others.
Tandarnia recoarensis and Tandarnia arachnoconcha, spicular Nassellaria of Middle Triassic(Dumitrica, 1982), are similar to ill-preserved
Parentactinia nakatsugawaensis. However, the767. Lower Triassic Palaeoscenidiidae from Kanto
Median173

bar

APicalText·fig. 5: Basal skeleton of Parentactinia.
nakatsugawaensis Sashida, n. sp.

former two species are easily distinguishable
from the latter by the disposition of its spines.
Reg. nos. IGUT 5817 (Holotype), 5818-5825(Paratypes) .
Genus Archaeothamnulus Dumitrica, 1982
Archaeothamnulus ramosus Sashida, n. sp.
PI. 37, Figs. 10-12

Diagnosis. -Skeleton formed of long spiculewith five sturdy spines arising from· center.
Commonly four of them diverge obliquely
downward and bear a vertical, and the otherspine arises apically and bears a vertical of shortspinules.
Description. -Siliceous spicule consisting of astraight axial spine and four slightly curved
basal spines. The four basal spines make anangle of 80-90 degrees with close vicinity of
the center, consisting of three spines convex
inward. At first joint, a stout rod-like tapering
spine branches to make an angle of about 120
degrees with its neighbours, and two or three
spinules divergent at the second joint. Boththe spines and basal spines of the whole skeleton are cylindrical.
Dimensions.-Axial length 30-50 microns,
total length of the preserved basal spines probably 500-600 microns. Maximum diameter ofmain spines 7-12 microns.
Remarks. -Five specimens have been recorded

Text-fig. 6: Parentactinia
nakatsugawaensis
Sash ida, n. sp. (scale = 30 microns)from the Ogamata Formation. The present
species is closely related to Archaeothamnulus
verticillatus reported by Dumitrica (1978b,1982) from the Lower Ladinian of theBuchenstein Limestone, Recoaro, Italy. However, the latter species has longer basal spine andone branching near the center. Deflandre (1973)
reported Xiphocladiella cuja from the Lower
Carboniferous in Montagne Noire. This species
has four to five basal spines and long axial
spines with complicated branching spinule atmiddle part. The basal skeleton of this species
slightly resembles Archaeothamnulus ramosus
Sashida, n. sp.
The species name is from Latin, ramus,
branching.
Reg. nos. IGUT 5827 (Holotype), 5828 and5829 (Paratypes).
Archaeothamnulus? sp.
PI. 36, Figs. 11-13

Description. -Four, long, slender, rod-likebasal spines, one or two rather short tapering
apical spines. The basal spines with smoothsurface, divergent to draw an arch, but someof them straight and tapering ends usually
curved inward. The apical spines shorter than athird to a fourth of the basal spines, and gently
curved downward.

174

Katsuo SASHIDA
sp. can be distinguishable from Tandamia
simplicima and other spicular Nassellaria by
the disposition of its spines. This species also
resembles Paleo~oic spicular Radiolaria Palacantholithus stellatus described by Deflandre(1973) from Montagne Noire in having longarched basal spines. However, the latter has
spinule at right angles to the basal spines.
Reg. nos. !GUT 5810 (Holotype), 5811 and5812 (Paratypes).
All specimens described herein are stored
in the collections of Institute of Geoscience,
the University of Tsukuba (!GUT).
References

Text·fig. 7: Archaeotbamnulus ramosus Sashida,n. sp. (scale = 25 microns)

Dimensions. -Basal spines 350-580 microns,
apical spines 100-140 microns? based on three
specimens.
Remarks. -Dumitrica(1982)
introduced
many Middle Triassic spicular Nassellaria fromthe Buchenstein Limestone. Among them,Tandamia simplicima is rather similar to thepresent species. However, Archaeothamnulus?

Deflandre, G. (1953): Radiolaries fossiles. In:
Grasse P.·P. Traite de Zoologie, vol. 1, p.
389-433, pI. 2, Paris.
--(1973): Sur quelques nouveaux types deRadiolaries Polycystines viseens, dattribution systematique ambigue, certains evoquantIi la fois des Plectellaires et des Spumellaires.
C. R. Acad. Se. Paris, vol. 276, p. 289-293,
pIs. 1-4.
Dumitrica, P. (1978a): Family Eptingiidae n.
fam., extinct Nassellaria (Radiolaria) withsagittal ring. D. S. Inst. Geol. Geofiz., vol.
64 (1976-1977), Part. 3, Palaeont., p. 2738, pIs. 1-4.

Explanation of Plate 36
Figs. 1-9: Arehaeosemantis venusta Sashida, n. sp.
1. holotype, x 250 !GUT. 5800
2. paratype, x340 !GUT. 5801
3. paratype, x 440 !GUT. 5802
4. paratype, x280 !GUT. 5803
5. paratype, x 320 !GUT. 5804
6. paratype, x320 IGUT.5805
7. paratype, x 280 !GUT. 5806
8. paratype, x320 !GUT. 5807
9. paratype, x 320 !GUT. 5808
Fig. 10: Archaeosemantis sp.
x250 !GUT. 5815
Figs. 11-13: Arehaeothamnulus? sp.
11. x150 !GUT. 5810
12. x170 !GUT. 5811
13. x200 !GUT. 5812

SASHIDA : Triassic Palaeoscenidiidae from Kanto

Plate 36

Katsuo SASHIDA

Text-fig. 8: Archaeothamnulus? sp. (scale = 50
microns)--(197 8b): Triassic Palaeoscenidiidae andEntactiniidae from the Vicentinian Alps
(Italy)and the Eastern Carpathians(Romania). Ibid. p. 39-54, pIs. 1-5.
--(1982): Middle Triassic spicular radiolaria.
Revista Espanola de Micropaleontologia,
vol. 14, p. 401-428, pIs. 1-7.
- - , Kozur, H. and Mostler, H. (1980): Contribution to the radiolarian fauna of the
Middle Triassic of the Southern Alps.
Geol. Palaeont. Mitt. Insbruck, 10, no. 1,
p. 1-46, pIs. 1-15.
Foreman, H. (1963): Upper Devonian Radiolaria
from the Huron Member of the Ohio Shale.
Micropaleontology, vol. 9, no. 3, p. 267304, pIs. 1-9.
Fujimoto, H. (1933): Stratigraphical studies on
the radiolarian chert of the Kwanto Mountainland (Preliminary Report). Jour. Geography. vol. 45, no. 533, p. 325-332. (inJapanese).
- - , Kawata, K., Miyazawa, S., Morikawa, R.,
Arai, F., Takano, T., Yoshida, S., Hara, K.,
Tazuke, H. and Mado, H. (1950): Geologicalstudy of Okuchichibu. Bull. Chichibu Mus.,
Nat. Hist., IJO. 1, p. 1-28. (in Japanesewith English abstract).
- - , Watanabe, K., Akagi, S., Iijima, H., Kaneko, S., Takano, J. and Matsuzaki, S. (1957):
Geology of the north-western part of the
Kanto Mountainland. Ibid. no. 7, p. 17-28.
(in Japanese with English abstract).
Furutani, H. (1982): Skeletal construction andphylogeny of Palaeoscenidiidae. JRS 81

175

Osaka, p. 11-16. (in Japanese with English
abstract).
- - (1983): Middle Palaeozoic Palaeoscenidiidae(radiolaria) from Mt. Yokokura, Shikoku,
Japan. Part 1. Trans. Proc. Palaeont. Soc.
Japan, N. S., no. 130, p. 96-116, pIs. 2127.
Holdsworth, B. (1977): Paleozoic Radiolaria:
Stratigraphic distribution in Atlantic borderlands. In F. M. Swain (ed.) Stratigraphic
micropaleontology of Atlantic basin andborderlands. Amsterdam, Elsevier. p. 167184.
Ishii, A. (1962): Upper Paleozoic of the Nakatsugawa area, Okuchichibu, Kanto-massif. Bull.
Chichibu Mus., Nat. Hist., no. 20, p. 178195. (in Japanese with English abstract).
- - , and Matsukawa, M. (1980): Ogamata Formation, Kanto Mountains, Central Japan.
Bull. Tokyo Gakugei Univ. ser. 4, vol. 32,
p. 195-207. (in Japanese with English
abstract).
Kozur, H. and Mostler, H. (1972): Beitrlige zur
Erforschung der mesozoischen Radiolarien.
Teil I: Revision der Oberfamilie Coccodiscacea Haeckel 1862 emend. und Beschreibung ihrer triassischen Vertreter. Geol.
Paliiont. Mitt. Insbruck, vol. 2 (8/9), p.
1-60, pIs. 1-4.
- - and - - (1978): Ibid. Teil II: Oberfamilie
Trematodiscacea Haeckel 1862 emend. undBeschreibung ihrer triassischen Vertreter.
Ibid., vol. 8 (Festschrift W. Heissel), p.
123-182, pIs. 1-5:--and - - (1979): Ibid. TeilIII: Oberfamilien
Actinommacea Haeckel 1862 emend., Artiscacea Haeckel 1882, Multiarcusellacea nov.
der Spumellaria und triassische Nassellaria.
Ibid., vol. 9 (1/2)1 p. 1-132, pIs. 1-2l.
--and--(1981): Ibid. Teil IV: Thalassosphaeracea Haeckel, 1862, Hexastylacea
Haeckel, 1882 emend, Petrusevskaja, 1979,
Sponguracea Haeckel, 1862 emend. undweiter triassische Lithocycliacea, Trematodiscacea, Actinommacea und Nassellaria.
Ibid., p. 1-208, pIs. 1-69.
Matsuda, T. and Isozaki, Y. (1982): Radiolarians
around the Triassic-Jurassic boundary fromthe bedded chert in the Kamiaso area,
Southwest Japan. JRS 81 Osaka, p. 93-10l.
(in Japanese with English abstract).
Mizutani, S. and Koike, T. (1982): Radiolarians

767. Lower Triassic Palaeoscenidiidae from Kanto

176

in the Jurassic siliceous shale and in the';I'riassic bedded chert of Unuma, Kagamigahara City, Gifu Prefecture, Central Japan.
JRS 81 Osaka, p. 117-134. (in Japanesewith English abstract).
Nakaseko, K. and Nishimura, A. (1979): Upper
Triassic Radiolaria from Southwest Japan.

Sci. Rep. ColI. Gen. Educ. Osaka Uniu.,
vol. 28, p. 61·-109, pIs. 1-12.
Nazarov, B. (1975): Lower and Middle Paleozoic
radiolarians of Kazahkstan (research methods, systematic, stratigraphic importance).
Acad. Sci. USSR, Trans., vol. 275, p. 1-204,
pIs. 1-21, Moskow (in Russian).
Pessagno, E., Finch, W. and Abott, P. (1979):
Upper Triassic Radiolaria from the San
Hipolite Formation, Baja California. Micropaleontology, vol. 25, no. 2, p. 160--197,
pis. 1-9.
Sash ida, K., Igo, Hh., Igo, Hy., Takizawa, S.,
Hisada, K., Shibata, T., Tsukada, K. andNishimura, H. (1982): On the Jurassic
Radiolaria from the Kanto Mountains.
JRS 81 Osaka, p. 51-66. (in Japanesewith English abstract).

Sato, T., Takizawa, S., Kuwahara, T., Sashida,K., Hisada, K., Aono, H., Fuseya, M. andArakawa, Y. (1981): Exotic nappes ofprobably sliding origin in the South Beltof the Kanto Mountains. Ann. Rep., Inst.
Geosci., Uniu. Tsukuba, no. 7, p. 56-59.
Takemura, A. and Nakaseko, K. (1982a): Jurassic
Palaeoscenidiidae from manganese ore deposits in the Mino Belt and their significanceon evolution and classification of Nassellaria.
JRS 81 Osaka, p. 173-182. (in Japanesewith English abstract).
--and---(1982b): Two new Jurassic
genera of family Palaeoscenidiidae (Radiolaria). Trans. Proc. Palaeont. Soc. Japan,
N. S., no. 128, p. 452-464, pIs. 70-73.
Wever, P., Sanfillippo, A., Riedel, W. and Gruber,
B. (1979): Triassic Radiolaria from Greece,
Sicily and Turkey. Micropaleontology, vol.
25,no.1,pls.1-7.
Yao, A., Matsuoka, A. and Nakatani, T. (1982):
Triassic and Jurassic radiolarian assemblages
in Southwest Japan. JRS 81 Osaka, p. 2744. (in Japanese with English abstract).

~JRI1J:!t!!.l: I).i&:-r 7.:> r$=~*J'&IIX.'H.1tE"-t0) 1 Palaeoscenidiidae: ~JRI1J:!t!!!lI1!:~~I::'~;fp-r 7.:> *1l-< 11 TltJ, I?, ~M-Cf~ff:~lfft.cr$=~*hl(/lt.'H.1tE"~~-t 7.:>0)J.&1IX.'H.1tE"~~I::'li Palaeoscenidiidae ~11 tab ~ <0) Spumellaria tJ~ft i n, mtE i -C 3~, 5 fito)
Palaeoscenidiidae tJ~~U]JJ ~ n -0" 7.:>
-Cli, <*o).l:? t.c Palaeoscenidiidae 5 fit (~, 3fit Iitifit) ~~~x Lt.:o Archaeosemantis venusta Sash ida, n. sp., Archaeosemantis sp.,
0

0

.:

.:.:

Parentactinia nakatsugawaensis Sashida, n. sp., Archaeothamnulus ramosus Sashida, n.
sp., Archaeothamnulus? sp.
om m Mf !i3

Explanation of Plate 37
1-9:
Parentactinia nakatsugawaensis Sashida, n. sp.
1. paratype, x350 IGUT. 5818
2. paratype, x200 !GUT. 5819
3. holotype, x 200 !GUT. 5817
4. paratype, x260 !GUT. 5820
5. paratype, x250 IGUT.5821
6. paratype, x280 !GUT. 5822
7. paratype, x 200 !GUT. 5823
8. paratype, x300 !GUT. 5824
9. paratype, x230 IGUT.5825
Figs. 10-12: Archaeothamnulus ramosus Sashida, n. sp.
10. paratype, x250 !GUT. 5828
11. holotype, x250 !GUT. 5827
12. paratype, x250 !GUT. 5829

Figs.

SASHIDA : Triassic Palaeoscenidiidae from Kanto

Plate 37

Trans. Proc. Palaeont. Soc. Japan, N. S., No. 131, pp. 177-190, pIs. 38-40, September 30, 1983

768. ON THE SUBGENUS WAKINOA(CRETACEOUS NON-MARINE BIVALVIA)
FROM GYEONGSANG GROUP, KOREA*SEONG YOUNG YANG
Department of Earth Science, Kyungpook National University,
Daegu 635, Korea

Abstract. In genus Trigonioides (s.1.), the sub generic difference can be readon the median V-ribs angle and the length ratio and the strength of the pseudocardinal hinge teeth, not the number of hinge teeth. Considering the stratigraphic
sequence as well as the taxonomic characters, Wakinoa is thought as transitional
form between Koreanaia and Trigonioides (s.s.). In addition, this paper contains
description of two species. of Wakinoa and a new species of Trigonioides (s.s.)from lower Gyeongsang Group, Korea.

Introduction and Acknowledgements

for his continuous encouragement during mystudy and critical reading of the typescriptof this paper. I would like also to thank Dr.
Minoru Tamura of Kumamoto University for
his friendly help including a guidance to fossil
localities in the Mifune group, and Mr. J. W. Kimof Kyungpook National University for his
support in field and laboratory works.
This study was financially supported by the
Korean Traders Scholarship Foundation.

Wakinoa has been known as an importantand interesting member in non-marine fauna of
the Mesozoic Asia together with Trigonioides(s.s.), Plicatounio, Nippononaia, and Koreanaia
since it was erected by Ota (1963) on "Nippononaia" wakinoensis from Japan. Wakinoa possesses
several common characters with other trigonioidid genera or subgenera. However, its taxonomic relation and stratigraphic positions are
not clearly grasped yet, because the fossil localities have been found in separate basins, and thefossil preservation is not sufficiently good.
This paper is to make clear the taxonomic
characters of Wakinoa, discussing its relationships with other relevant subgenera, and todescribe two species of Wakinoa and a new
species of Trigonioides (s.s.) from Korea.
Acknowledgements. -I would like to express
my sincere gratitude to Emeritus Professor
Tatsuro Matsumoto of Kyushu University

Relationship of Wakinoa with otherSubgenera of Genus Trigonioides
At present, the genus Trigonioides contains
four subgenera, Trigoniodes (s.s.), Wakinoa,
Koreanaia, and Kumamotoa. These subgenera
possess common characters in both of thesurface ornamentation and the internal structures. On the surface ornamentation, the subgenera are characterized by the V-shaped medianribs and reversed V-ribs on both the anterior andposterior parts. As to the internal structures,the two subequal adductor scars and the minute* Received September 29, 1982; read October
3,1981, at Hiroshima.
177

Seong Young YANG

178

pedal scar as well as the hinge teeth, 5, 4, 3, 2/
PII, PIlI, PIV are in common in all the subgenera.
The subgeneric difference can be read in boththe median V-ribs angle and the hinge structure.
As previously mentioned (Yang, 1974, 1976,1979), the median V-ribs angle is larger than 35
degrees in Koreanaia, about 30 degrees in
Wakinoa, and less than 20 degrees in Trigonioides(s.s.) and Kumamotoa.
Before discussing the subgeneric difference inthe hinge structure, the synopsis on the dental
formulae can be shown as follows:
Koreanaia;
5
3
PIlI
4
2 PII
PIV
Wakinoa;
5
3
(1)
PIlI
4
2
PII
PIV
Trigonioides (s.s.);
3
5
1
PIlI
4
(1') PII
2
PIV

5
(6)

3
4

1a

1b
l'a

2

(T. kodairai)

1c
l'b

PIlI
PII

PIV

(T. paucisulcatus)
Kumamotoa;
5
3
1a
PIlI
4
2
(l'a) PII
PIV

5
(6)

3
4

1a
2

1b
l'a

(Kzi. suzukii)

PIlI(l'b) PH

PIV

(Ku. mitunensis)(Ku. matsumotoi)

On account of the number of hinge teeth,
there must be a problem in the classification ofsubgenera as pointed out by Tamura (1981).
That is, T. kodairai and Kumamotoa suzukii
would not be discriminated from each other,and Kumamotoa mitunensis and Kumamotoa
matsumotoi would be also considered as members of Trigonioides (s.s.). In addition to theabove dental formulae, considering the hinge

structure of a new species of Trigonioides (s.s.)(described below), the number of the pseudocardinal teeth is gradually increased with upward
stratigraphic sequence. Therefore the number ofthe pseudocardinal teeth cannot be considered
as subgeneric taxonomic character.
However, the sub generic difference can befound on other hinge characters such as thetransverse crenulations, the relative length ofthe pseudocardinals and the morphology ofhinge plates. The transverse crenulations on thehinge teeth are also the important common
character in the present genus except some of
the Koreanaia spp. (K. cheongi and K. yunnanensis). But the crenulations on the pseudocardinals are very fine in both of Wakinoa
and Koreanaia but fairly strong and rather stout
in Kumamotoa. In Trigonioides (s.s.), they arealso regular but <:>f intermediate intensity between the above two. Furthermore, there is adifference in the. relative length of the pseudocardinals between the subgenera. That is, theratio of 1a to 3 is less than 0.3 in Trigonioides(s.s.) but larger than 0.6 in Kumamotoa (Yang,1974). In other words, the submedian pseudocardinals 1a and 1b are fairly long in Kumamotoa, but rather short and weak in Wakinoa
and Trigonioides (s.s.). And the hinge plateof Kumamotoa is wider than that of any othersubgenera. For these comparisons, Text-figure
1 and Figures 8-20 of Plate 39 are shown.
Considering the stratigraphic horizons of thefossils as well as the taxonomic characters,
Wakinoa is regarded as a transitional form
between Koreanaia and Trigonioides (s.s.).
Incidentally, Trigonioides kodairaiformis
Martinson, 1965, from southeastern Fergana,
U.S.S.R., is considered to be referred to Wakinoa
rather than to Trigonioides (s.s.) in its surface
ornamentation (Martinson, 1965, pi. 1, figs.
1-5) and hinge teeth.

Systematic Description
Superfamily Unionacea
Family Trigonioididae Cox, 1952

768. On the Subgenus Wakinoa

5 3 la lb

KPE 1023

f' t

F7111

179

5 3 1a 1b 1c

Pili- -,-~_tL-. L!-"'j'-",,_---1-f

i

KPE 1690

I

T. paucisulcatu

KPE 1110-'-----'--'----'f"'------Li_=l'---_.L..f KPE 16B'
Ku. mifunensis[

KPE 1197

KPE 2097

KPE 1030

1

KPE 1028

KPE 1044(GK 1500)

KPE1045(Wuk 100)

KPE 2096

T. jaehoi n. sp.

'hi

-'-~

.....L-JUL-.L..t,It-'-- -+ Ku. matsumotoi-+ Ku. suzukii,I ~T. kodairai
KPE 2323

W. cf. W tamurai

20mm

KPE 2322[....,. Ko. bongkyuni
KPE 2503

I
I
I
I

KPE 2093

KPE 2092

KPE 2371

KPE 2375

T.: Trigonioides (s. s.)
Ku.: Kumamotoa

10

W.: WakinoaoKo.: Koreanaia

Text-figure 1. Comparison of the subgeneric differences in hinge teeth of the genus Trigonioides.
Crenulation: illustrated by short horizontal lines,
Tooth length: expressed by vertical line.

Seong Young YANG

180

Subgenus Wakinoa Ota, 1963

Measurements (in mm) of
Trigonioides (Wakinoa) sp. cf.
T. (W.) tamurai

wakinoensis
Type-species. -"Nippononaia"
Ota,1959.
Subgeneric diagnosis (emend.).-Shell medium
in size, suboval to subelliptical in outline, subequilateral and equivalve. Umbo moderately highand prosogyrous, located at about two fifth of
the shell length from the anterior extremity.
Hinge plate moderate in breadth, provided withthe short pseudocardinal teeth and long posterior
lateral ones, the pseudocardinals two or three onright valve, two on left valve, and the posterior
lateral ones one on right valve, two on left valve,
forming the following dental formula:H
L/H
L
Specimens
1.31
45.3
Conjoined (KPE 2311) 59.2
Left valve (KPE 2312) 35.6++ 27.9
Left valve (KEP 2314) 42.5++ 38.9
15.8+
Left valve (KPE 2315) 25.3+
34.1
Left valve (KPE 2316)
1.57
15.0
Left valve (KPE 2317) 23.6
31.6
Right valve (KPE 2319)
Right valve (KPE 2348) 40.3++ 32.2+
34.6
1.22
Conjoined (KPE 2352) 42.2
42.6
1.17+
Conjoined (KPE 2364) 49.7+

Genus Trigonioides Kobayashi and Suzuki, 1936

5

3
4

(1)
2

PIlI
PII

PIV

where 4, 3 and PIlI: with fine transverse crenulations on both sides, 5 and PII: with fine transverse crenulations on posterior (or dorsal) side
only, (1) and PIV: with fine transverse crenulations on anterior (or ventral) side only, and 2
crenulated on both sides or anterior side only.
Both muscle scars well defined, the anterior one
accompanied with a minute pedal scar. Inner
ventral margin crenulated. Surface ornamented
with numerous V-shaped ribs in the median partand the reversed V-ribs on both of the anterior
and the posterior sides, the angle of the medianV-ribs about 30 degrees.
Trigonioides (Wakinoa) sp. cf.
T. (W.) tamurai Yang, 1976
PI. 38, Figs. 1-15, Text-fig. 2
Material. -Thirty four specimens (KPE 231133, 2348-56, 2364-65) collected from the lightgrey siltstone and greenish grey greywacke of theupper Middle Hasandong Formation, Nagdong
Subgroup, Gyeongsang Group, Korea (CoIl. S.
Y. Yang).

Text-figure 2. Trigonioides (Wakinoa) sp. cf.
T. (W.) tamurai Yang, 1976.
a: surface ornamentation and outline of theleft valve,b: internal structures of the left valve.

768. On the Subgenus Wakinoa
Descrip tion. -Shell medium in size (about
2o--BO mm in length), generally suboval in
outline; subequilateral and equivalve; anterior
margin well rounded, posterior one rather
straight and obtusely angulate at the posteroventral comer, ventral margin broadly arcuate;
umbo fairly prominent, slightly prosogyrous,
placed at about two-fifths of shell length fromthe anterior extremity, and projected slightly
above the hinge line. Test moderate in thickness.
Surface ornamented with numerous V-shaped
ribs in the median part and the reversed V-ribs
on both of the anterior and the posterior sides.
The antero-ventral half occasionally ornamented
with multiple V-ribs on some specimens. The
angles of the median V-ribs about 30 degrees andthose of the reversed V-ribs on both sides about
45---130 degrees. The subradial ribs and grooves
on the posterior half much stronger and wider
than those on the anterior half. The subradial
median ribs number more than 18 on the anterior half and more than 12 on the posterior halfon the adult large specimens. The whole surface
ornamented also with fine numerous concentric
growth-lines of irregular interval and prominence.
Posterior ridge running from the umbo down tothe postero-ventral comer.
Hinge plate moderate in breadth, provided
with opisthocline pseudocardinal teeth andpostero-Iateral teeth; the pseudocardinal ones
two or three on the right valve, two on left
valve; the postero-Iateral teeth one on the rightvalve, two on the left valve, forming the following dental formula:
5

3

4

(1)

2

PIlI

PII

PIV

where 5: narrow and elongated, with fine transverse crenulations on the ventral (lower) side
only, parallel to the antero-dorsal margin,
3: largest and highest in the right valve,with fine transverse crenulations on both sides,
subparallel to the antero-dorsal margin,
1: smallest and low in the right valve,occasionally indistinct, with a few fine transverse crenulations on the anterior side only,
nearly vertical,

181

PIlI: longest in the right valve, with veryfine transverse crenulations, rather striations,on both sides on the crest of the tooth, parallelto the postero-dorsal margin,
4: elongated highest in the left valve, withfine transverse crenulations on both sides, subparallel to the antero-dorsal margin,
2: moderately elongated, sloping obliquely
toward the antero-ventral side, crenulated whollyon the antero-dorsal side, but only in upper parton the posterior side,
PII: narrow and elongated, with very finetransverse crenulations on the dorsal (upper)
side only, parallel to the postero-dorsal margin,
PIV: narrow and elongated, with very finetransverse crenulations on the ventral (lower)side only, parallel to the postero-dorsal margin.
Two adductor scars subequal in size, theanterior one strongly impressed, accompaniedwith a minute pedal scar, the posterior one
somewhat larger but not so distinct. Pallial line
simple. Inner ventral margin crenulated. Umbonal
cavity moderate in depth.
Observation. -The specimens are fairly wellpreserved, but severely deformed except forseveral of them. Among the thirty four specimens, there are eleven conjoined ones, thirteenright valves and ten left valves. The tests are in
general well preserved, and so the internal
structures are observed on the five internalmoulds artificially made with dilute hydrochloricacid.
Occurrence. -The specimens were collectedfrom the light grey siltstone and greenish grey
grey wacke at Bulnodong, Hyoryeong-myeon,
Gunwui-gun, Gyeongsangbug-do, Korea (seeText-figure 3-A). The fossiliferous bed contains
plenty of the molluscan fossils besides thepresent species; Plicatounio (s.s.) spp., Nagdongia
soni, and Viviparus sp.
Remarks. -The specific name, Wakinoa
tamurai was proposed for the specimens,
Wakinoa tetoriensis of Tamura (not Maeda's
Trigonioides tetoriensis, 1963) on the differencesof the surface ornamentation and the hinge teeth
by Yang (1976).
The present specimens are most similar to
Wakinoa tamurai in surface ornamentation and182

SeongYoung YANG

A

I

0.5

0

bw'nlI!

111111114~:~~Ilo

It;:::;:j 9

768. On the Subgenus Wakinoa

hinge teeth, but precise comparison is difficult
because of the insufficient preservation of thespecimens from Japan. However, it can be safely
said that the present specimens are more similar
to Wakinoa tamurai than any other species
referred to Wakinoa on the development of thesubmedian hinge tooth (1), and the multiple
V-sculptures on the antero-ventral half. And it
can be also safely discriminated from the speciesof Trigonioides (s.s.) and Kumamotoa on thefairly large angle of the median V-sculpture
and the fine crenulations of the hinge teeth.
In the latter subgenera, the angles of the Vribs are generally less than 20 degrees and thecrenulations on the hinge teeth are regular andprominent. And it is also discriminated fromthe species of Koreanaia on the smaller anglesof the V-ribs on the median part in which theangles are 35-45 degrees.
Trigonioides (Wakinoa) wakinoensis(Ota),19632671-2) are collected from the lower Yeonhwadong Formation at Impo, Hwangumri, Golyagmyeon, Gwangyang-gun, Jeonranam-do, Korea(see Text-figure 3-D). Here, the present species
is associated with Plicatounio sp. and Pseudohyria sp. And the other one (KPE 2410) is
collected from the middle Yeonhwadong Formation at Wari, Yulgog-myeon, Habcheon-gun,
Gyeongsangnam-do, Korea (see Text-figure 3-B).
At this locality, Nagdongia son~ Nippononaia
ryosekiana, Viviparus sp. and dinosaur's bones
are associated with the present species.
At the above three localities, the specimensof the present species are severely deformed andquite poorly preserved as minority of the faunas.
Therefore, the outline and the internal structures
can not be clearly defined on these specimens.
However, the surface ornamentation such as Vsculptures and the angle of the Vs can be safely
identified with that of W. wakinoensis fromJapan.
Subgenus Trigonioides
Kobayashi and Suzuki, 1936

PI. 39, Figs. 1-7

1936. Trigonioides kodairai Kobayashi and
Suzuki, Japan. Jour. Geol. Georgr. ,vol. 13, nos. 3-4, pI. 29, fig. 13.
1941. Trigonioides kodairai Kobayashi and
Suzuki, Bull. Geol. Inst. Manchoukuo,
no. 101, figs. 1-4.
1959. "Nippononaia" wakinoensis Ota, Trans.
Proc. Palaeont. Soc. Japan, N. S., no. 34,
p. 107,108, pI. 11, figs. 1-7,11.
1959. "Nippononaia" sengokuensis Ota, Ibid.,
p. 108, pI. 11, figs. 8-10.

MateriaL -Eight specimens (KPE 2401-5,
2671-2, 2410) collected from the light grey
siltstone of the lower to middle Yeonhwadong
Formation, Gyeongsang Group, Korea. (KEP
2401-5; ColI. K. H. Chang: KPE 2671-2, 2410;
Coil. S. Y. Yang).
Occurrence. -Among the specimens, KEP
2401-5 are collected from the lower Yeonhwadong Formation at Hwanggyeri, Yongjumyeon, Habcheon-gun Gyeongsang nam-do,
Korea (see Text-figure 3-C)_ At this locality,
the present species is associated with Nagdongia
soni, and Viviparus sp. Two specimens (KPE

183

Type-species. -Trigonioides kodairai Kobayashi and Suzuki, 1936.
Subgeneric diagnosis (emend.).-Postero-Iateralhinge teeth two on left valve, one on right valve,
forming the following dental formula:
5
(6)

3
4

1a
2

(lb)
(1 'a)

(lc)
(l'b)

PIlI
PH

PIV

The other characters same as in my previous
descriptions (Yang, 1974, p. 396-398; Yang,
1978,341-342).
Included species. -Trigonioides kodairai Kobayashi and Suzuki, 1936; Trigonioides paucisulcatus (Suzuki), 1940; Trigonioides tetoriensis
Maeda, 1963; Trigonioides jaehoi, sp. nov. (described below).
Trigonioides (Trigonioides) jaehoi, sp. nov.
PI. 39, Figs. 9-10; PI. 3, Figs. 1-16, Text-fig. 4

Etymology. -This species is dedicated to Mr.
Jaeho Oh of the Korea Institute of Energy andSeong Young YANG

184

Resources who discovered the fossil locality andkindly introduced me to the locality and helpedin sampling.
Measurements (in mm) of
Trigonioides (Trigonioides) jaehoi

Length Height
Specimens
Right valve (KPE 2001) 43.8 31.8
Conjoined (KPE 2002) 46.4 33.2
Left valve (KPE 2004)
40.0 26.2+
Conjoined (KPE 2005) 44.8 32.1
Left valve (KPE 2006)
44.2 33.1
Conjoined (KPE 2007) 44.9 31.4+
Conjoined (KPE 2009) 46.1 31.6
Left valve (KPE 2011)
38,6 29.0
Right valve (KPE 2013) 37.3 26.3
Conjoined (KPE 2014) 44.0 30.3
Conjoined (KPE 2016)* 45.5 33.3
Left valve (KPE 2019)39.6 30.6
Right valve (KPE 2022) 38.3 28.3
Left valve (KPE 2025)
43.3 30.2
Conjoined (KPE 2031) 34.1+ 27.4
Conjoined (KPE 2036) 41.3 32.9
Conjoined (KPE 2041) 37.8+ 28.7
Left valve (KPE 2042)
43.0 31.7
Right valve (KPE 2052) 39.0 29.3
Left valve (KPE 2057)
48.2 37.0
Left valve (KPE 2058)
59.2 40.3

L/H
1.38
1.40
1.531.40
1.34
1.431.46
1.33
1.42
1.45
1.37
1.29
1.35
1.43
1.25
1.26
1.32+

projected slightly above the hinge line, slightly
prosogyrous and placed at about two-fifths fromthe anterior extremity; moderate in inflation;
escutcheon and lunule both present.
Surface ornamented with V-shaped ribs on
the median part and reversed V-ribs on bothof the anterior and posterior parts. The anglesof the median V-ribs about 10-15 degrees andthose of the reversed V-ribs on both sides about
50-60 degrees. The subradial median ribs on
the anterior side finer and weaker but denser
than those on the posterior side. The ribs on
the antero-ventral part generally effaced, becoming indistinct. The median ribs number 13
to 19 in the anterior half and 10 to 12 in theposterior half, the ribs sloping obliquely toward
outer dorsal sides number more than 10 on
the antero-dorsal side and 18 on the posterodorsal side; the whole surface ornamented alsowith numerous concentric growth-lines ofirregular interval and prominence.
Hinge plate moderate in breadth, provided
with opisthocline pseudocardinal teeth andpostero-Iateral teeth, the pseudocardinal teeth
three or four on both valves, and the posterolateral ones one on right valve, two on left valve,
forming the following dental formula:

1.36
1.33

5
(6)

3
4

1a
2

(1b)
1'a

PIlI
PIT

PIV

1.30
1.47

Conjoined valve (KPE 2016)*: holotype.
MateriaL -Holotype (KPE 2016, PI. 40,
Fig. 14) and one hundred and one paratypes(KPE 2001-2102) collected from the grey
calcareous siltstone of the upper horizon of
the Hasandong Formation, Nagdong Subgroup,
Gyeongsang Group, Korea (ColI. S. Y. Yang).
Description.-Shell medium in size (about
40-60 mm in length), equivalve and subequilateral; suboval in outline, with ratio of L/H
about 1.35; anterior margin well rounded,
posterior one subquadrate, ventral margin
broadly arcuate; umbo somewhat prominent,

where 5: narrow and elongated, with regulartransverse crenulations on both sides or ventral(lower) side only, parallel to the antero-dorsal
margin,3: most prominent and largest in the pseudocardinal teeth of the right valve, crenulated on
both sides, subparallel to the antero-dorsal
margin,1a: low and short, crenulated on both sides,
obliquely downward to the antero-ventral
margin,1b: smallest in the right valve, sometimes
indistinct, crenulated on anterior side only,
nearly vertical,
PITI: prominent and elongated, with finetransverse crenulations on both sides, parallel768. On the Subgenus Wakinoa

185

Text·figure 4. Trigonioides (Trigonioides) jaehoi, sp. nov.
a: surface ornamentation of the left valve.
b: internal structures of the left valve.
c: internal structures of the right valve.

to the postero-dorsal margin,
6: narrow and elongate, sometimes indistinct,
crenulated lower side only, parallel to anterodorsal margin,
4: largest pseudocardinal tooth in the left
valve, crenulated on both sides, subparallel tothe antero-dorsal margin,
2: moderate and elongated, sloping obliquely
toward the antero-ventral side, crenulated
wholly on the antero-dorsal side, but only on
the upper part on the posterior side,
l'a: smallest in the left valve, crenulated on
both sides, nearly vertical,
PH: narrow and elongated, with fine transverse crenulations on the dorsal (upper) side
only, parallel to the postero-dorsal margin,
PIV: narrow and elongated, more or lessshorter than PII, with fine transverse crenulations on the ventral (lower) side only, parallelto the postero-dorsal margin.
Two adductor scars subequal in size andform, anterior one subcircular, strongly impressed, accompanied with a distinct minutepedal scar; posterior one also subcircular andmore or less larger, but not so distinct; shell
margin crenulated internally; pallial line simple
and distinct on the anterior half, but indistinct

on the posterior half; umbonal cavity moderately
deep.
Observation. -The holotype (KPE 2016) is aconjoined valve, 45.5 mm in length and 33.3 mm
in height. Among the 102 type-specimens, 42
are conjoined, 31 right valves and 29 left valves.
Most of the specimens are well preserved but
secondarily deformed. It is notable that even theligaments are well preserved on some of thespecimens (PI. 3, Figs. 1, 2a, 3a). The subradialribs on the median part are fairly effaced on theanterior half of the most specimens. The internal
structures have been observed on the ten adultspecimens about 40 mm in length from which
the tests were dissolved out with dilute hydrochloric acid.
Occurrence. -The fossils occur separately here
and there not gregariously. Of the conjoined
specimens, the commissure planes are generally
posed vertically and the antero-posterior axes
inclined to stratification. Among the collection,
the conjoined specimens occupy a relatively
large number (about 41.2%). And all show nosevere destruction besides secondary deformation. These facts may suggest that the fossils
have been preserved in situ.
The fossil locality is at a river channel near

186

Seong Young YANG

Text-figure 5. Geological map around the fossil locality of Trigonioides (Trigonioides) jaehoi,
sp. nov.
1. Yeonhwadong Formation, 2. Hasandong Formation, 3. Dongmyeong Formation.
In index map, B: Busan, J: Jinju, D: Daegu, G.S.B.: Gyeongsang Basin.

Explanation of Plate 38
Figures 1-15. Trigonioides (Wakinoa) sp. cf. T. (W.) tamurai Yang, 1976
1. Right valve (KPE 2322), 1a; internal mould, 1b; rubber cast, showing the hinge teeth.
2. Left valve (KPE 2324), 2a; internal mould, 2b; rubber cast, showing the hinge teeth.
3. Right valve (KPE 2320), external mould, showing the multiple V-sculpture on theanterior part faintly.
4. Right valve (KPE 2323), 4a; internal mould, 4b; rubber cast, showing the hinge teeth.
5. Left valve (KPE 2317), slightly compressed and anterior side somewhat broken out.
6. Right valve (KPE 2313), posterior part broken out.
7. Left valve (KPE 2315), posterior part broken out and slightly compressed vertically.
8. Left valve (KPE 2314), strongly compressed antero-posteriorly.
9. Left valve (KPE 2312), showing the multiple V-sculpture on the antero-ventral part,the postero-ventral part broken out.
10. Left valve (KPE 2354), showing the reversed V-ribs on the antero-dorsal part.
11. Right valve (KPE 2319), showing the multiple V-ribs on the anterior part, the posterior
part broken out.
12. Right valve (KPE 2348), posterior part broken out.
13. Left valve (KPE 2316), the posterior part broken out.
14. Left valve (KPE 2318), the antero-ventral part broken out.
15. Conjoined valve (KEP 2311), 15a; left valve, 15b; right valve, compressed laterally.
All figures are approximately of natural size. Locality; see Text-figure 3-A.

YANG : Subgenus Wakinoa

Plate 381a....

.,..., iI_.

~___ ....

'----~- -1/- - -----''-''" ---

5

,
/

/
'-

7 ..-/

I
~

,

10
9

(
...

j •

"-

768. On the Subgenus Wakinoa

Yusuri, Nadong-myeon, Jinyang-gun, Gyeongsangnam-do, Korea (see Text-figure 5)_ The
associates of the present species at the locality
are Plicatounio (P.) spp. and Viviparus sp.
Comparison. -Trigonioides (s.s.) kodairai andthe present species are much alike each other insurface ornamentation and outline. However,examining in more detail, specific differences
can be grasped. In the present species the ribletson the antero-dorsal side are fewer, and on thepostero-dorsal side more numerous than in T.
(s.s.) kodairai, respectively. And except a few
specimens, the species described here is ornamented with the subradial ribs on the umbonal
area and the posterior half, but the ribs aregradually effaced towards the antero-ventral
margin. This effacement is also observed on thespecimens of T. (s.s.) kodairai, but more distinctly in the present species. With this respect,
the present species is intermediate between T.
(s.s.) kodairai and T. (s.s.) paucisulcatus. A
similar transitional feature is seen in the hinge
teeth, T. (s.s.) kodairai possesses pseudocardinalteeth, three on the right valve and two or three
on the left valve, and T. (s.s.) paucisulcatushas five on the right valve and four or five on theleft valve of large adult specimens, even though
ontogenetic variation is observed. While thepresent species possesses three or four on both
valves. In the number of the pseudocardinalhinge teeth, the present species is fairly similar
to Kumamotoa spp., but easily discriminatedfrom the latter in the ratio of the length of theteeth and the strength of the transverse crenulations.
In the stratigraphic sequence, the present
species also falls in the intermediate position
between T. kodairai and T. paucisulcatus.

References
Kobayashi, T. and Suzuki, K. (1936): Nonmarine shells of the Naktong-Wakino series.

187

Japan. Jour. Geol. Geogr., vol. 13, nos. ·3-4,
p. 243-257, pis. 27-29.
--and --(1941): On the occurrence ofTrigonioides in south-eastern Manchuria.
Bull. Geol. Inst. Manch., no. 101, p. 77-8l.
Maeda, S. (1963): Trigonioides from the late
Mesozoic Tetori Group, central Japan. Trans.
Proc. Palaeont. Soc. Japan, N. S., no. 51,
p. 79-85, pI. 12.
Martinson, G. G. (1965): Biostratigraphy andfauna of continental Cretaceous of Fergana.
(in Russian), Sci. A cad. U.S.S.R., p. 101152, pis. 1-11.
--(1965): Cretaceous lamellibranchia family
Trigonioididae and its classification. Pal.
Jour. Sci. Acad., U.S.S.R., no. 4, p. 16-25.
(in Russian).
Ota, Y. (1959a): Trigonioides and its classification (Studies on the molluscan fauna of theCretaceous Inkstone series, pt. 2). Trans.
Proc. Palaeont. Soc. Japan, N. S., no. 34,
p. 97-104, pI. 10.
--(1959b): On the "Nippononaia" from theCretaceous Wakino Subgroup, north Kyushu,
Japan. Ibid., no. 34, p. 105-110, pI. 1l.
--(1963): Notes on the relationship of Tri·gonioides and Plicatounio, non-marine
Mesozoic bivalvia from eastern Asia. Geol.
Rept. Hiroshima Univ., no. 12, p. 503-512.
Tamura, M. (1981): A summary of the Cretaceous non·marine bivalve studies in Japan atpresent. Earth Sci. Jour., vol. 90, no. 6,(846), p. 369-392. (in Japanese).
Yang, S. Y. (1974): Note on the genus Trigonioides (Bivalvia). Trans. Proc. Palaeont.
Soc. Japan, N. S., no. 95, p. 395-408, pis.
54-55.
--(1976): On the non-marine molluscan faunafrom the Upper Mesozoic Myogog Formation, Korea. Ibid., no. 102, p. 317-333, pis.
33-34.
- - (1978): Ontogenetic variation of Trigonioides(s.s.) paucisulcatus (Cretaceous non-marine
bivalvia). Ibid., no. 111, p. 333-348, pis.
45-46.
--(1979): Some new bivalve species from thelower Gyeongsang group, Korea. Ibid., no.
116, p. 223-234, pis. 27-28.

188

Seong Young YANG

Explanation of Plate 39
Figures 1-7. Trigonioides (Wakinoa) wakinoensis (Ota), 1963.
1. Left valve (KPE 2672), dorsal part not preserved, compressed laterally.
2. Right valve (KPE 2403), strongly compressed antero-posteriorly.
3. Right valve (KPE 2402), umbonal part only.
4. Right valve (KPE 2405), strongly compressed and the ventral part broken out.
5. Left valve (KPE 2671), strongly compressed and the median part only.
6. Conjoined valve (KPE 2401), 6a; left valve, 6b; right valve, strongly compressed.
7. Left valve (KPE 2410), inner view, anterior part broken out, external mould shown.
Loc.: (KPE 2671) (KPE 2672); see Text-figure 3-B.
(KPE 2401-5); see Text-figure 3-G.
(KPE 2410); see Text-figure 3-D.
Figure 8. Trigonioides (Wakinoa) sp. cf. T. (W.) tamurai Yang, 1976. Right valve (KPE 2323),
internal mould, showing the hinge teeth. Loc.: see Text-figure 3-A.
Figures 9-10. Trigonioides (Trigonioides) jaehoi, n. sp.
9. Left valve (KPE 2094), internal mould, showing the internal structures.
10. Right valve (KPE 2098), internal mould, showing the hinge teeth.
Loc.: (KPE 2094, 98); Yusuri, Nadong-myeon, Jinyang-gun, Gyeongsangnam-do, Korea (seeText-figure 5).
Figures" 11-12. Trigonioides (Trigonioides) paucisulcatus, Suzuki, 1940.
11. Right valve (KPE 1687), internal mould, showing the hinge teeth, the specimen strongly
compressed antero-posteriorly.
12. Right valve (KPE 1690), internal mould, showing the hinge teeth.
Loc:(KPE 1687, 90); at a point about 1.5 km northeast from Geoncheonri, Seo-myeon, Weolseong-gun, Gyeongsangbug-do, Korea (see Yang, 1978).
Figures 13-19. Trigonioides (Kumamotoa) mifunensis Tamura, 1970.
13. Right valve (KPE 1023), 13a; internal mould, showing the internal structures, anterodorsal part only, 13b; rubber cast.
14. Rubber cast of right valve (KPE 1110), antero-dorsal part only, showing the internal
structures.
15. Left valve (KPE 1198), showing the hinge teeth.
16. Right valve (KPE 1028), 16a; internal mould, showing the internal structures, 16b;
rubber cast.
17. Left valve (KPE 1022), internal mould, showing the hinge teeth.
18. Left valve (KPE 1199), internal mould, showing the internal structures.
19. Right valve (KPE 1197), internal mould, showing the hinge teeth.
Loc.: (KPE 1022, 23, 28, 1110, 1197-99); at about 500 m southeast from Tashiro, Kosa town,
Kumamoto, Japan (the type-locality of T. (K.) mifunensis).
Figure 20. Trigonioides (Kumamotoa) matsumotoi Kobayashi and Suzuki, 1941.
Rubber cast (KPE 1044) of the GK 1500, showing the internal structures.
All figures are approximately of natural size.

YANG : Subgenus Wakinoa

Plate 39

3

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16a

19

20

18

768. On the Subgenus Wakinoa

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Wakinoa ~~tr Trigonioides ~O)!!Ii:~
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1.!ri"7.:>o Trigonioides ~O)llli~7tMI:"ft pseudocardinals ~t':(1"~~·r\i.i"7.:>~)ftft, Tamura(1981) t.M[1~ L.t..:.t ? l:..rR'JiW!;lJti6 7.:>L7'J'L, pseudocardinals ~t':(1"<:tJ:-t;M,t:)O)~~
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Seong Young YANG

Explanation of Plate 40
Figures 1-16. Trigonioides (Trigonioides) jaehoi, sp. nov.
1. Conjoined valve (KPE 2005), dorsal view, showing the lunule and the ligament.
2. Conjoined valve (KPE 2001), 2a; dorsal view, showing the lunule and the ligament,
2b; left valve side view, compressed laterally.
3. Conjoined valve (KPE 2014), 3a; dorsal view, showing the lunule and the ligament,
3b; left valve side view.
4. Left valve (KPE 2004), slightly compressed vertically.
5. Conjoined valve (KPE 2031), right valve side view, somewhat compressed laterally.
6. Left valve (KPE 2024), posterior part broken out.
7. Right valve (KPE 2022), posterior part broken out.
8. Right valve (KPE 2013), posterior part broken out.
9. Conjoined valve (KPE 2002), left valve side view, compressed laterally.
10. Conjoined valve (KPE 2009), left valve side view, posterior part broken out and com·pressed laterally.
11. Conjoined valve (KPE 2041), right valve side view.
12. Left valve (KPE 2019), side view.
13. Conjoined valve (KPE 2007), left valve side view, slightly deformed.
14. Conjoined valve (KPE 2016), left valve side view.
15. Left valve (KPE 2011), side view.
16. Left valve (KPE 2006), side view.
KEP 2016 (Figure 14) is the holotype and the others are the paratypes.
All figures are approximately of natural size.
Loc.: Yusuri, Nadong-myeon, Gyeongsangnam-<io, Korea (see Text-figure 5).

YANG: Subgenus Wakinoa

Plate 40

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Transactions and Proceedings of the PalaeontologicalSociety of Japan
September 30, 1983

New Series No. 131

CONTENTS
TRANSACTIONS
Presidential Address. HAN AI, Tetsuro: A story of the belemnite - an approach based on
the method of inventing auxiliary assumptions in paleontology . . . . . . . . . . 125765. ISHIZAKI, Kunihiro: Ostracoda from the Ananai Formation . . ... . . . . ...... . . 135
766. OMURA, Akio: Oxygen and carbon isotopic composition in the skeleton of anahermatypic scleractinian coral, Dendrophyllia japonica Rehberg .~':;: .. . .. . .. 159
767. SASHIDA, Katsuo:

Lower Triassic Radiolaria from the Kanto Mountains, central

Japan. Part 1: Palaeoscenidiidae . . ... . . . . . . . . . . . . . . . . . . . ....... 168
768. YANG , Seong·Young: On the subgenus Wakinoa (Cretaceous non·marine Bivalvia)
from Gyeongsang Group, Korea . .. ... . .. . . . . . . . . . . . . . . . . . . . . . . 177