No. IX. ECHINODERMATA. 263 



fucicolaffiom Assistance Bay (Capt. Penny's voyage), and 

 by Stimpson from Grand Manan in the Bay of Fundy. It is 

 found also on the coast of Massachusetts, Gulf of Georgia 

 (Salenka), San Francisco (Ayres), along the whole Scandi- 

 navian coast, Iceland, Fa3roe Islands, and in the English 

 Channel. 



(7. frondosa attains great dimensions, the present indivi- 

 dual (one specimen only was obtained) being but small ; its 

 length is 80 millims., and diameter about 50 millims. 



ECHINOIDEA. 

 Strongylocentrotus drobachiensis (Miiller), A. Ag. 



Coll. Feilden: Eichardson Bay, 70 fms. (young); Frank- 

 lin Pierce Bay, 15 fms., bottom-temperature 29*5 F. ; 

 Cape Napoleon ; Hayes Point, 35 fms., bottom-temperature 

 29-5 F. 



Coll. Hart: Discovery Bay, 15-20 fms., muddy bottom; 

 Franklin Pierce Bay, 13-15 fms., stony. 



Owing to the extensive range of this boreal echinoid, the 

 variations to which it is subject are so great that there are 

 perhaps few other species which include in their synonymy 

 so large a number of modern determinations. Distant observers, 

 depending upon the stability of ' local forms,' have founded 

 numerous so-called new species, all of which have hitherto, 

 however, proved untenable when due comparison has come to 

 be made with a large series of specimens. 



The northern varieties, known as 8. granulatus (Say), 

 Gould, and 8. chlorocentrotus, Brandt, fail to present any 

 characters of sufficient importance to warrant their separation 

 from the drobachiensis group, although when isolated and 

 extreme examples are compared the differences at first sight 

 appear very marked. 



Similarly with the specimens collected by the recent Ex- 

 pedition, separate individuals placed by the side of a single 

 8. drobachiensis from a more southern habitat present 

 superficially a striking divergence. 



