78 



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

 body; back with one or two scattered tubercles. 



Var. Back -vvith a blunt tnbercie 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. 



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

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

 minutely granular. Marginai ossicules -J-^ on each side, convex, 

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

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

 orai 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 knovvn 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 (restrictcd). 



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

 protected by triangular ossicules, each covered with numerous erect, 

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

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

 cules, covered vi^itli 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 ^vith cylindrical trun- 

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

 forming a rounded group, and \vith a series of similar, rather larger 

 spines on their side, and a series of small ossicules vvith terminai 

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



Messrs. Miiller and Troschel have proposed a genus under this 

 name,vi'hich I have hererestricted to smaller limits, to more accurately 

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



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



tubercled. 

 AsTROGONiuM GRANULARis. Astcrias granularis, Retz. Dis. ; 

 Mūller, Zool. Dan. t. 92. f. 1. 



Pentagonai, sides rather concave. Back bright crimson ; orai sur- 

 face yellowish ; marginai 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 orai 

 surface similar, but granules longer. 



Inhab. North Sea. British Museum. 



