:nn 



THE VOYAGE OF H.M.S CHALLENGER. 



in the northern hemisphere, except possibly in the extreme north, has no marsupial 

 arrangement such as we find in the Kerguelen Cidaris. There have passed through my 

 hands during the last few years hundreds of specimens of the normal northern form, of the 

 Mediterranean varieties Cidaris hystrix and Cidaris affinis (stokesii), and of the American 

 Cidaris abyssicola? from widespread localities and of all ages; and I have never found the 

 young except singly, and never in any way specially associated with breeding individuals. 

 " In Stanley Harbour we dredged many specimens of an irregular urchin, much 

 resembling in general appearance Brisso2Jsis lyrifera, the common ' fiddle urchin ' of the 



boreal province of the British seas, and probably 

 to be referred to Hemiaster philippii, Gray. 2 



" These urchins were not -breeding when we 

 were at the Falklands, but on the 9th of January 

 1874 we dredged from the pinnace in shallow water, 

 varying from 20 to 50 fathoms, with a muddy 

 bottom, in Accessible Bay, Kerguelen Island, in- 

 numerable samples of apparently the same species. 

 "The test of a full-sized example (fig. 143) is 

 about 45 mm. in length and 40 mm. in width ; the 

 height of the shell in the female is 25 mm., in 

 the male it is considerably less. The apex is 

 nearly in the centre of the dorsal surface ; the 

 genital openings are three in number, in the female 

 very large; the bilabiate mouth is placed well 

 forward On the ventral aspect; and the excretory 

 opening is posterior and supramarginal. The odd 

 anterior ambulacrum is shallow, and the tube-feet which are projected from it are large 

 and capitate. The anterior paired ambulacra are somewhat longer than the posterior. 

 The whole of the surface of the test is covered with a close pile of small spines of a dark 

 green colour ; those fringing the ambulacral grooves are long and slightly curved, and 

 they bend and interdigitate so accurately over the ambulacra that one might easily over- 

 look the grooves at a first glance. The peripetalous fasciole is somewhat irregular ; but 

 in those examples in which it is best defined it forms a wide arch, extending backwards 

 on each side a little beyond the lateral ambulacra of the trivium, and then, contracting 

 a little, forms a rudely rectangular figure round the bivium. The paired ambulacra] 

 grooves in the male are shallow, not much deeper than the anterior ambulacrum 

 (fig. 145) ; in the female the pore-plates of the paired ambulacra are greatly expanded and 



Accessible 



Fig. 143. — Hemiaster earernnsus (Phil.). 



Bay, Kerguelen Island. Twice the natural size. 



1 These are regarded by Alex. Agassiz as varieties or developmental stages of Dorociiarit papillata ; see Zool. 

 Cliall. Exp. part ix. p. 44, &c., 1881. 



2 Described by Alex. Agassiz as lit iniaster carernoms (Philippi), loc. eU., p. 177. 



