149 
is not at all identical with “ Porocidaris“ elegans. ') It represents 
not only a hitherto undescribed species but it must even be made 
the type of a new genus, though recalling in some .important feat¬ 
ures the genus Austrocidaris, which is, apparently, its nearest ally. 
No specimens were taken by myself during my cruises in the 
New Zealand seas, only some isolated radioles were found off 
White Island, 55 fms., undoubtedly belonging to the same spec¬ 
ies. Thus I have to base the description on the two specimens 
placed at my disposal by Prof. Ben ham, to whom I beg to offer 
my best thanks. I take the pleasure of dedicating this new spec¬ 
ies to him. 
Apical Ambulacra Interambulacra Longest 
Diameter. Height. system. Peristome. Width. Plates Width. Plates. radioles. 
a. 20 11 10 8 2,5 33 9,5 6-7 — 
b 19 10 9,5 8 — — — 6-7 30 
The measurements are in mm. In specimen 
a. none of the longer radioles were intact; spec¬ 
imen b. is preserved as an alcoholic specimen 
and exact measurements of the ambulacral and 
interambulacral areas therefore cannot be given. 
The test (PI. VI, Figs. 4—6) is flattened 
above and below, sligtly incurved at the oral 
edge, the peristome being somewhat sunken. 
Both ambulacral and interambulacral areas with 
a distinet sunken midline. The interambulacral 
plates number 6 — 7. The areoles are fairly 
deep, only the three, small, lower ones confluent. No crenulation_ 
The scrobicular circle .not very prominent, the tubercles of it being 
only slightly larger than those outside, which are few, close set; those 
towards the median side project irregularly into the sunken median 
Fig. 2. Part of ambu- 
lacrum of Oymocidaris 
Benliami. 8 /i. 
b The correct name is Histocidaris elegans (A. Ag.), in spite of Benham’s 
rejection of the generic name Histocidaris. He did so, relying on Agas- 
s i z’ declaration that my nierhod — using the microscopic characters of 
the pedicellariæ as distinguishing characters of species and genera — 
was unscientific. I do not think anybody would venture to maintain 
this any more. But there is a bit of nemesis here. If Ben ham had 
taken the trouble to look at the pedicellariæ, he would at once have 
seen that this species could not possibly be identical with “Porocidaris” 
elegans. 
