%^ 
12 POROCIDARIS SHARREEI. 
from the fossil species, in the way of spines associated with their respect- 
ive tests. 
When alive these Echini were of a brilliant vermilion color. 
Among the specimens of D. Blukci there are a number without fan- 
shaped radioles ; others, in which there were only one or two of the slightly 
flattened radioles similar to those of Plate II. Fig. 5 ; others again, in which 
there were a few radioles like those of Plate II. Fig. 7; and others, in which 
a few of the fan-shaped radioles took the extrtiordinary development we find 
figured in Plate I. 
Dorocidaris papillata A. Ac. 
For localities see Bull. M. O. Z., V., No. 9, p. 185, 1878 ; Bull. M. C. Z, Till., No. 2, p. 70, 1880. 
On our coast this species has been found hy the " Blake " as far north as 
Lat. 32° 33' N., Long. 77° 30' W. Along the Florida reefs, in the Gulf of 
Mexico, and along the West India Islands, it is tlie most common sea-urchin 
V found from about 100 to 300 fathoms. I have dredged it to a depth of 842 
fathoms off the Grenadines. 
* Porocidaris Sharreri A. Ag. 
Porocidaris Sharreri A. Ag. Bull. M. C. Z., VIII., No. 2, p. 71, 1S80. 
Nevis, Barbados, 122-35G fathoms. 
PL III., PL IV. Figs, i, £ 
This species differs from its Atlantic congener, P. purpurata Wy. Th., in 
having a comparatively larger number of ambulacral plates, — no less than 
fifteen for the median interambulacral plates (PI. IV. Fig. 1) in the largest 
specimen collected, while in a specimen of P. prtrpuruia of nearly the same 
size there are only ten ; the ambulacral granulation is also much finer, and 
the large areolar ring of comparatively large granules is flanked by smaller 
granules arranged in irregular lines parallel to the suture. We find no 
such arrangement in the coarse granulation of the intei'ambulacral plates 
of P. furpuvidn. 
This is a larger species (PI. TIT.) than either of the other recent ones thus 
far known. The two largest specimens collected were males ; a single small 
female, measuring slightly over an inch in diameter, shows that in this 
species, as in P. clegam. the genital openings are placed within the genital 
plates (PI. W. Fig. 2 ). 
