1894.] ECHINODERHS OE MACCLESFIELD BANK. 405 



sharp spine ; the plates that bear such spines are most numerous 

 near the bases of the arms. There are eight fine spines bordering 

 the narrow ambulacral groove, the shortest of which are at the 

 sides, and the whole set of which forms a fan-like expansion ; 

 there follow on these four upright and stouter spines. The arm- 

 plates are covered with fine projecting glassy spines, which, on the 

 disc, are blunt. 



R=87 - 5, r=9-5. Breadth of arm at base 7*5. Height of 

 arm 7' 5. 



Macclesfield Bank, 30-40 fms. 



If I am right, which I very much doubt, in assigning this species 

 to the genus Chcetaster, the diagnosis of the genus will have to be 

 so far altered as to include the possible possession by the plates of 

 the arms of central projecting spines. A difference in the com- 

 bination of circumstances makes it sometimes right, sometimes 

 wrong, to form a new genus or a new species on the evidence 

 afforded by a single specimen ; in the present case I can only 

 briefly give the evidence of the existence of a type hitherto 

 unrecognized. 



Ophidiasteb, helicostichus. 



Ophidiaster helicostichus, Sladen, Chall. Rep. Ast. xxx. p. 405. 



Two fine specimens, one from Holothuria Bank (15 fms.) and 

 the other merely reported as from N.W. Australia, are so much 

 larger than the specimens which I have referred to my Linckia 

 megaloj)la,v, that I cannot assert that they are all members of one 

 species, but I have very little doubt on the point. 



RhIPIDASTER VAjOLPES. 



Rhipidastcr vannipes, Sladen, Chall. Rep. Ast. xxx. p. 448. 



I am inclined to think that two small specimens, one of which 

 is quite minute, from 32 fms. may, when a full series is obtained, 

 be shown to be the young of this species founded on a single 

 specimen, the spread of which is more than 170 millim. Between 

 them at present it seems useless to make a comparison. Both 

 the small specimens have nine arms. 



ASTERIAS VOLSELLATA. 



Asterias (Stolasterias) volsellata, Sladen, Chall. Rep. Ast. xxx. 

 p. 584. 



A small example of this species, the only other known example 

 of which is the one that formed the basis of Mr. Sladen's description, 

 is another of the finds on which Mr. Bassett-Sraith is to be con- 

 gratulated. The whole spread of this new specimen is less than 

 30 millim., but its Brisinga-\ike appearance is no more marked 

 than that of the " type." 



It has unfortunately been in recent years so rare an occurrence 

 for me to be able to agree with the views of the describer of this 

 species, that I gladly seize the opportunity of saying that he seems 



Pboc. Zool. Soc— 1894, No. XXVII. 27 



