the echinoid fauna from japan and adjacent regions part i

The Echinoid Fauna from Japan and Adjacent Regions 231
ous as those of the outer series. Gill-slits quite obsolete. Valves of small globiferous
pedicellariae with the flattened and widened blade.
No recorded as fossils.
In possessing the test with very small pits and a distinctly limited naked area
in the midline, this genus has resemblance to the genus Microcyphus AGASSIZ, 1841,
as to the habits, but this genus is easily distinguished from the latter by distinctly
biserial arrangement of the pore-pairs and much more numerous coronal plates. From
the genus Amblypneustes AGASSIZ, 1841, this genus differs in having the median space
of aboral interambulacral areas is more or less extensively bare and free from spines
and tubercles.
This genus contains a well known and very diversified species, M. globulus
(LINNAEUS, 1758) (with some varieties), and a doubtful species (or subspecies of that
species), but there has been no record of occurrence as fossils from anywhere.
The very characteristic structure of the naked part of the coronal plates, i. e., a
peculiar porous-radiating structure, was noticed first by MORTENSEN (1943, p. 177).
This seems to be a peculiar feature among the test-structure of the Echinoids.
There are fragmentary specimens of a species of this genus in our collection,
derived from the' Raised Beach deposits' of Central Japan. They are not regarded
as fossil in a strict sense, but for convenience's sake they are described herein.
Mespilia globulus (LINNAEUS, 1758)
(PI. 6, fig. 1)
Mespilia globulus (LINNAEUS) AGASSIZ and DESOR, 1846, p. 358, pI. 15, figs. 17-17a.-A.
AGASSIZ, 1872-74, pp. 143, 477, pI. 6, fig. I, pI. 8a, figs. 13-14, pI. 8c, fig. 14, pI. 38, figs.
22, 22a-c.-BELL, 1880-d, p. 434.-BELL, 1881-b, p. 433.-MACKINTOSH, 1883, p. 255, pI. fig.
31.-DoDERLEI"i, 1885, p. 95 (24).-DE MEIJERE, 1904, p. 87.-MoRTEl\:SEN, 1904, p. 96, pI.
6, fig. 17, pI. 7, figs. 16, 22, 23, 47.-ToKUNAGA, 1906, pI. 8, figs. 17-19.-H. L. CLARK,
1912-b, p. 322.-H. L. CLARK, 1925, p. 93.-KoEHLER, 1927, p. 88.-RoxAs, 1928, p. 256, pI.
2, figs. 7-9.-IKEDA, 1935, p. 422.-MoRTENSEN, 1943, p. 177, pI. 12, figs. 1-17, pI. 21. fig.
19, pI. 45, figs. 9, 18, 20, 32, text-figs. 47c, 48c. 96, 97a-b, 98a-b, 99, 100-102.-H. L. CLARK,
1946, p. 315.-UTINOMI, 1954, p. 347.
M espilia levituberculatus Y OSIllW ARA, 1898, p. 58.-TOK UN AGA, 1906, pI. 8, figs. 20-23.
Salmacopsis pulchellimus YOSIIl\\' ARA, 1898. p. 59.
Locality and geological horizon.-IGPS loco no. Ch-27.-Small cliff of the River
Heguri at Kuwabara, H6j6-machi, Tateyama City, Chiba Prefecture. (tm Nago, Lat.
35°0'23"N., Lat.l39°53'08"E.). Raised Beach deposits, early Holocene. Hypotype.-IGPS
colI. cat. no. 78305.
There are several fragmentary specimen referred to this species at hand, the
largest one consists of one ambulacra and one and a half interambulacral areas.
Ambulacra broad, as broad as, or more or less narrower than, the interambulacra,
7 mm wide at the ambitus; ambulacral plates low and broad, 3.5 mm wide and about
1 mm high at the ambitus, composed of three components, a middle demi-plate component
and aboral and adoral primary components; pore-pair of middle demi-plate
component placed outside as broad as the distance of pores of a pair, and pore-pairs
of aboral and adoral primary components arranged in a single series, as pore-pair of
adoral primary just superposed on pore-pair of aboral primary of the successive