PROPAOA'JCION OF CEllTAIN ECUINODER.VfS. 



67 



are dislodged from the marsupium. This species seems to 

 acquire its full size during a single season. We dredged it at 

 the close of the breeding-season, and we took no specimens inter- 

 mediate in size between the adult and the young. 



III. ECHINOIDEA PETALOSTICHA. 



In shallow water, varying from 20 to 50 fathoms, with a muddy 

 bottom, in Accessible Bay, Kergueleu's Land, we dredged on the 

 9th of January, 1874, from the steam-pinnace, innumerable Urchins 

 very much resembling in general appearance Brissopsis h/rifem, 

 the common Fiddle Urchin of the boreal province of the British 

 seas. The group to which these Urchins belong requires careful 

 revision ; but it seems, from the absence of the subanal fasciole and 

 from some other characters, that the species at present under con- 

 sideration must be referred to the genus Hemiaster ; and it is very 

 probable, from its great abundance in ordinarily accessible depths 

 that it will turn out, on comparison, to be one of the species 

 brought home by Sir James Clark Eoss's Antarctic Expedition. 



Fig. 6. 



Hemiaster, sp. Twice the natural size. 



