76 SCHIZASTEK ORBIGNYANUS. 
* Schizaster orbignyanus A. Ag. 
Schizaster orbignyanus A. Ag. Bull. M. C. Z., VIII., No. 2, p. 84, 1880. 
Lesser Antilles. 92-1 3U7 fathoms. 
PI. XXVIII. Figs. 1-7. 
This species extends as far north as the New England coast, specimens 
having been dredged by the United States Fish Commission off Martha's 
Vineyard in 100 and 130 fixthoms. They differ very considerably from the 
specimens dredged by the Blake in the Eastern Caribbean. The northern 
specimens, while retaining the chai-acteristic outline of those from the Carib- 
bean, yet differ from them in having a much broader peripetalous fasciole, 
more like that of >S'. camdifcrus ; the northern and southern specimen;;, again, 
agree in the great width of the actinal plastron at the posterior extremity, 
and the small size of the anal system as compared with that of S. cuna- 
li/'crus, and are covered by a closer tuberculation also, a character which 
readily distinguishes the specinrens «f the two species thus far compared. 
The test from the lower side of the anal system to the edge of the actinal 
plastron is more bevelled than in S. canaliferus. In the few specimens ot 
S. orbignyanm I have had occasion to examine, the lateral and anal fascioles 
vary greatly in distinctness. In the Caribbean specimens the lateral fasciole 
extends continuously along the sides of the test to the level of the side of 
the anal system, and there forms a sharp, well-defined triangular anal fasciole. 
In the northern specimens the lateral fasciole is often indistinct or disappears 
entirely, only the anal fasciole remaining. It is interesting to note that, in 
the specimens of S.fragilis dredged off our eastern coast, the anal fasciole 
disappears first, leaving only a part of the lateral fasciole extending from the 
peripetalous fasciole towards the anal system. The peripetalous fascioles 
are of a dark violet color, forming a strong contrast to the greenish yellow 
spines with silvery lustre which cover the upper part of the test. The lateral 
and anal fascioles can scarcely be distinguished by their color from the spines 
of the actinal side and those towards the ambitus, wliich with the exception 
of the spatula-shaped spines of the actinal plastron are of a darker color than 
those of the abactinal side of the test, and within the peripetalous fasciole. 
Whether the differences here noted between S. cunalifenis and S. orhigmj- 
anits are merely local or more important, comparisons of more extensive series 
of these species alone can determine. 
