76 



Stellaster Incei. 



PurpHsh, minutely granular ; back -vvith scattered, conical, convex 

 tubercles, those down the centre of the arm largest. The lower 

 marginai platės are flattish. 



Inhab. North Australia. 



This species is very likę Stellaster Childreni, Gray, Ann. and Mag. 

 Nat. Hist. 1840, 278; Muller, Aster. 62. 128. t. 4. f. 3; Asterias 

 eguestris, Retzius, Diss. 12 ; but it is purplish when dry ; the back 

 is tubercular ; the whole surface is minutely granular ; while the 

 Japanese species is always white, the back smooth, and the granules 

 of the surface are so minute and thin that they are very easily eroded, 

 and the lower marginai platės are more convex and the centrai ones 

 much larger than the others. 



Stellaster Belcheri. 



Back convex, with two or three large conical tubercles on the line 

 extending to the centre of the arms. Arms slender, tapering, rather 

 longer than the diameter of the disc. 



Inhab. Amboina or New Guinea. 



This species is intermediate between S. Childreni and S. Incei, 

 having the white colour and the slender arms of the former, and the 

 convex back and tubercles of the latter, but the tubercles are larger 

 and fewer, and the arms are more slender, having only a single 

 series of platės betweeu the marginai ones. 



There are two specimens in spirits and one dry, in the British 

 Museum collection. 



Calliderma. 



Body flat, five-sided, rays rather elongated ; attenuated end only 

 formed of the marginai platės. Ossicules all minutely granulated; 

 the dorsal ossicules flat- tipped, six-sided,some vidth a larger, globular, 

 centrai tubercle-like granule. The marginai ossicules broad, gradually 

 becoming smaller near the tip, short-edged. minutely granular, those 

 of the upper and lower series alternating ; the edge of the upper 

 ones with some indistinct spines on the margin, the lower ones with 

 scattered mobile spines on the orai surface. The ossicules of the orai 

 surface three-, four-, or six-sided, granular, with one (rarely two) 

 centrai, compressed,acute, mobile spines. The ambulacral spines very 

 small, close, fourteen or sixteen on each ossicule, forming a rounder 

 group, -vvith two or three series of large, scattered, mobile, acute 

 spines on the outer side. 



This genus resembles Stellaster, but difFers from it in the orai 

 surface being furnished with scattered spines. 



There is a fossil species very likę the one here described found in 

 the chalk, and figured in Mr. Dixon's \vork on the fossils of Wor- 

 thing, •which I propose to call Calliderma Dixonii. There are pro- 

 bably several other fossil species from the šame locality ; they have 

 been referred to the genus Tosia, but the ossicules are granular and 

 the orai surface spinose. 



