276 BULLETIN OF THE 



remarkable that we should have in Brissopsis similar variations, in the 

 sub-anal fasciole, to these upon which Trosehel has founded his genera Abatus 

 Hamaxitus and Atrapus, — changes which, in Brissopsis at least, are due to 

 different stages of growth. The character of continuity of the adjoining 

 pairs of ambulacra, which Desor assigns to Toxobrissus as a distinguishing 

 feature, does not constitute a sufficient basis for its separation from Brissop- 

 sis. This character is more and more apparent according to the size of 

 the specimens ; so much so, that we should place Brissopsis lyrifera, when 

 young, in Brissopsis, but when full grown it would most decidedly pass for 

 a Toxobrissus. If the subanal fasciole is really absent in Toxobrissus, it 

 cannot, as Liitken considers it, be identical with Kleinia. It may be that 

 other characters will yet be traced to separate it from Brissopsis ; if not, 

 then Kleinia and Toxobrissus will both become synonymous with Brissopsis. 

 From 55 to 15G fathoms. 



Agassizia excentriea A. Ao., nov. sp. 



Syn. Agassizia porifcra McCr., PI. Foss. S. C, PI. 1, fig. 5. 



I am somewhat inclined to consider this species as the Agassizia porifera ; 

 but not having any original specimens for comparison, and the drawings 

 of Ravenel and McCrady showing rather striking differences, I will not take 

 their identity for granted, and compare it only with the West Coast repre- 

 sentative, from which it can at once be recognized by the position of the 

 apical system, which is much more eccentric posteriorly ; on this account 

 the disparity between the odd anterior pair of ambulacra anil the posterior 

 pair is greater than in that species. The interambulacral plastron is ellipti- 

 cal, and with this exception the arrangement and proportion of the tuber- 

 cles is that of A. ovulum Lutk. The peripetalous fasciole does not pass be- 

 low the ambitus, and the posterior fasciole makes a sharp angle under the 

 anal opening. 



I am unable to distinguish Agassizia scrobiculata, of which authentic spe- 

 cimens are in the Museum collection, from A. ovulum. I must say, however, 

 that Valenciennes's drawings in the Venus are not very faithful, and, from 

 an identification based upon his figures alone, specific diilerences would 

 readily become apparent. 



From 36 to 115 fathoms. 



Echinocardium ovatum Gray, Cat. Brit. M. 



Syn. Amphidctus ovatus Ac, Agass. Cat. Rais. 



E. orthonotus McCr., P. Foss. S. C, PL 2, fig. 1. 



An examination of young specimens of Echinocardium cordatum shows 

 that the generic distinction which I attempted to make between Amphide- 



