the echinoid fauna from japan and adjacent regions part i

The Echinoid Fauna from Japan and Adjacent Regions 187
the imperforate interambulacral primary tubercles, and by the compound ambulacral
plates of the salenioid structure throughout, which are made up of two primary
components. This genus is distinguished from its allies, Trisalenia LAMBERT, 1895
(1895, p. 262.-Type-species-Tr. loveni (COTTEAU) MORTENSEN, 1932-d, p. 485, pI. 4,
figs. 4-10, pI. 4, figs. 4-10, pI. 5, figs. 13-14, text-figs. 10-11, 14-16), and Polysalenia
MORTENSEN, 1932 (1932-d, p. 490.-Type-species-Pol. notabilis MORTENSEN, 1932-d,
p. 491, pI. 4, figs. 1-3, text-figs. 17-22), by the structure of the ambulacral plates at
the ambitus.
The genus Salenia dates back to the Neocomian and ranges down to the Recent,
but flourished in the Senonian Epoch, and a very few number survived in the Recent
seas.
There is a fossil species of this genus in our collection, as described herein.
Salenia novemprovincialis NISIY AMA, n. sp.
(PI. 2, figs. 6-9)
Holotype and paratypes.-IGPS coil. cat. no. 73750.
Locality and geological horizon.-IGPS loc. no.-Ns-11.-Southern sea-cliff of
Otoko-jima, Sakito-mura, Nishi-Sonogi-gun, Nagasaki Prefecture. (tm Kakino-ura,
Lat. 33°00'16/1N., Long. 129"32'30/lE.), Kakinoura formation, Oligocene (or Lower
Miocene). NAGAO, 1927.
There are six specimens of this new species at hand; they are more or less
broken and crushed by subsequent crustal deformation; the best preserved one is
selected as the holotype.
Test of rather small size, about 24 mm in horizontal diameter, and rather low,
nearly a half of the horizontal diameter or a little more; both oral and aboral sides
flattened, apical system slightly elevated; oral side simply flattened, scarcely sunken
at the peristomial edge.
Ambulacra slightly sinuate, aborally narrowed, about 3 mm wide at the ambitus,.
but suddenly widening at some distance from the peristome. Primary ambulacral
tubercles form two very regular series in the ambulacra, conspicuously distinct in
spite of their small size, on account of interporiferous area being somewhat raised;
at the ambitus the tubercles increase a little in size, then become smaller below the
ambitus, and again become larger towards the peristome, and finally decrease in
size as to become very small on approaching to the peristomial edge; tubercles
mamillate, no trace of crenulation, and not quite contiguous; primary series very
close to the poriferous zone so that there is scarcely room for a distinct double
series of secondary tubercles between them, especially on the aboral side. Pores
rather large, and arranged in a single, regular series, as usual in the Saleniids, and
there are very regularly two pore-pairs par tubercle; ambulacral plates rather low;
at least 30 in a column.
Interambulacra broad, about 11 mm wide at the ambitus, at least 11 plates in each
column, each plate with a large primary tubercle, excepting the uppermost one or two
in each series, which are covered with small secondary tubercles only; large tubercles
distinctly crenulate; areoles of large ambital primary tubercles comparatively large,