Botany and Zoology. 419 



In A. vulgaris the major pedleellarice are laveeolate, sharp- 

 pointed, much longer than broad ; the adambulacral spines are 

 longer, more pointed, and seldom fiattened. 

 The dorsal spines are variable in form and number in both 

 species, but are usually more acute in the latter, though blunt and 

 even clavate spines often occur on both species. The number of 

 minor pedicellariae on the spines, and of major ones on the back 

 and also on the adambulacral spines, is extremely variable in both 

 species. Yet these are the characters mainly relied upon by M. 

 Perrier for distinguishing his supposed species. Three of the 

 " species " recognized by him are evidently mere forms of ^1. vul- 

 garis. These are A. Fabricii (Agassiz, MSS.), based on one dry 

 specimen from Laborador; A. pallidus (Agassiz, MSS.) based 

 mainly on six small dry specimens, sent, like the preceding, from 

 the Museum of Comparative Zoology in 1 864, and in a very bad 

 state of preservation, the spines being mostly detached by partial 

 decompor'"^'' ^ ' .i -. • -^ .i • / i. , , 



„..i 1 A J Ferrier, who imagined that 



that he refers t 



garis, one from Beverly, Mass!, and one in the British Museum. 

 The latter was probably sent by Dr. Stimpson, who commonly 

 used labels marked " Exploration of the East Coast of the United 

 States" (not " west " coast, as M. Perrier gives the label), for his 

 ■New England collections. I had given "^. Fabricii^'' after ex- 

 amining original specimens, as a synonym of A. vulgaris in my 

 paper of 1866 ; and gave "■A. pallidus'''' as an undoubted synonym 

 in my Report of 1873-4. All the characters given by M. Perrier 

 as distinctive are variable and partly accidental features that can 

 oe found, with all intermediate states, in any considerable collec- 

 tion of this species from a single locality. These manuscript 

 names were given by Prof L, Agassiz before he had made a very 

 thorough study of the genus, but in a conversation, in 1871, while 

 we were dredging in company in Vineyard Sound and obtaining 

 both species in abundance, he fully agreed with me that there 

 were only two large species of this group known on our coast, and 

 ne also positively identified the numerous good specimens of A. 

 vulgaris with his A. pallidus ; and likewise the A. Forhesii (or 

 arenicola) with his A. berylinus. Dr. Wm. Stimpson in a conversa- 

 tion with me not long before his death, also agreed with these 

 decisions. Had M. Pemer examined a good series of specimens he 

 also would surely have found it impossible to have made the use- 

 less distinctions that he nowproposes, based on such very insufficient 

 material. In my Report of 1873-4 T stated that A. ForbesH and 

 ^. arenicola are "probably identical," the differences noticed 

 (mainly in form and color) " being, perhaps, chiefly sexual," but 

 not desiring to make premature changes, I left them under the 

 two names, only because I had then no time to determine whether 

 the differences are sexual, or properly varietal, or due to local or 

 individual variations. Subseq 



