Zoological Society. 199 



rather convex ossicules ; the arms as long as the diameter of the 

 body ; back with one or two scattered tubercles. 



Var. Back with a blunt tubercle on the centre of each of the ossi- 

 cules of the middle of the back. 



Inhab. ? 



This species is easily known from the former by the smaller gra- 

 nules on the surface, the length of the arms, and the small size of the 

 two-lipped pores ; those of the dorsal surface are very minute. 



HOSIA SPINULOSA. £" ^ j( <J^ 



Body flat, pentagonal, sides concave ; arms not half the length of 

 the diameter of the body ; ossicules large, subequal, six-sided, very 

 minutely granular. Marginal ossicules \% on each side, convex, 

 deeply separated from each other with a series of two or three small, 

 acute, spine-like tubercles in the centre of each. The ossicules of the 

 oral surface flat, minutely granular, with small two -lipped pores. 



Inhab. Indian Ocean ; Philippines. 



This species nearly resembles the shape of Tosia australis, but is at 

 once known from that species by the granular ossicules, the spines on 

 the margin, and the two-lipped pores beneath ; it differs from Hosia 

 flavescens in its being five-sided instead of five-armed, and in having 

 no spines on the middle of the back. 



Astrogonium (restricted). 



Body pentangular, flat above and below. Back and oral surface 

 protected by triangular ossicules, each covered with numerous erect, 

 cylindrical, truncated tubercles or granules, those of the oral surface 

 longest. Margin strengthened with regular, oblong, four- sided ossi- 

 cules, covered with small regular granules, except on the most con- 

 vex part of their centres, those of the upper and lower series opposite 

 each other. Dorsal wart single. Ambulacra with cylindrical trun- 

 cated spines, in groups of four on each ossiculus of equal size, not 

 forming a rounded group, and with a series of similar, rather larger 

 spines on their side, and a series of small ossicules with terminal 

 granules on their outer sides. Bilabiate slits are on either surface. 



Messrs. Muller and Troschel have proposed a genus under this 

 name, which I have here restricted to smaller limits, to more accurately 

 distinguish the species. I have described all we have in the Museum. 



A. Body flat, five-sided; granules short ; ossicules flat-topped, not 



tubercled. . 



Astrogonium granularis. Asterias granulans, Retz. Dis. ; Lil/* { 

 Muller, Zool. Dan. t. 92. f. 1. 



Pentagonal, sides rather concave. Back bright crimson ; oral sur- 

 face yellowish ; marginal ossicules oblong, \% on each side, rather 

 convex, covered, except at the most convex part of the upper and 

 lower surface, with very minute granules. Dorsal ossicules hexa- 

 gonal, flat-topped, with short flat-topped granules ; ossicules of oral 

 surface similar, but granules longer. 



Inhab. North Sea. British Museum. 



