342 APPENDIX. 



with numerous small conical acute spines, without any 

 larger tubercles, the upper marginal plate indistinct. 



Inhab. 



This species is very like the former in shape, size, and 

 appearance, but is very easily known from it by the 

 numerous mobile acute spines, with which the back and 

 upper part of the margin are covered, appearing to take 

 the places of the small granulations, and by the absence of 

 the tubercles on the elevated ribs of the back. 



Asterodiscus, Gray. 

 Body pentagonal, coriaceous, depressed, covered with 

 numerous close flat-topped unequal small tubercles ; back 

 convex ; dorsal wart roundish, subeentral ; arms short, 

 rounded, with a pair of large convex kidney-shaped 

 ossicules on each side of the tip above ; margin simple 

 rounded, beneath concave, ambulacra with a series of short 

 linear spines, placed in groups of four or five, each group on 

 a separate ossicule, and with two series of larger blunt 

 clubshaped spines on the outside of the ambulacral spines. 



Asterodiscus elegans, n. s. 



Pale brown when dry, tubercles of the back unequal, the 

 larger ones truncated, those nearest the mouth on the 

 underside larger, clubshaped, rather crowded. 



Inhab. — Japan. Brit. Mus. 



Pent ace ros granulosus, n. s. 



Five-rayed, rays as long as the diameter of the disk, 

 rounded at the tip ; back rather convex. 



Ossicules convex rounded, all covered with close rounded 

 granules, the two or three central ones on the top of each 

 ossicule being larger, those on the middle of the back largest, 

 and subtubercular. 



The marginal ossicules convex rounded. 



Inhab. — Western Australia. 



