the echinoid fauna from japan and adjacent regions part i

c
e
The Echinoid Fauna from Japan and Adjacent Regions 225
Test low, about 0.6 of horizontal diameter, beautifully rounded above, a little
curved inwardly at the peristome. Pits (in both areas) small, not reaching to the
base of primary tubercles, leaving thus a rather large part of horizontal suture not
depressed; a faint covering membrane seen around the edge of pits. Primary
tubercles (of both areas) form a distinct longitudinal series in a column, diminishing
very little in size towards the apical system and the peristome; they are almost
equally there in both areas; in larger specimens, tubercles rather crenulate, and
there may be indication of a stellate structure at their base. Secondary tubercles
rather numerous, in larger specimens very crowded, forming more or less distinct
vertical and horizontal series; in the ambulacra inside the primary series there is a
vertical series of secondary tubercles, which may be slightly smaller than the pri-
a
Fig. 11. Temnotrema sculptum A. AGASSIZ, test-diameter. x S.
Numerals on the figures indicate the ordinal nUfj1ber of plate from the peristome.
a. An ambulacrum and two of half interambulacra on the adapical region; b. An interambulacra
and two of half ambulacra on the adapical region; c. An ambulacrum and two of half
interambulacra at the mid-zone; d. An interambulacrum and two of half ambulacra at the
mid-zone; e. An ambulacrum and two of half interambulacra at the peristomial region; f.
An interambulacrum and two of half ambulacra at the peristomial region.
b
f
d