126 Mr. H. J. Carter on the 



numerous. Upper parts black, with the neck and a short 

 stripe in the middle of the back white ; another white curved 

 band on each side of the back. A more or less distinct black 

 stripe along the middle of the abdomen. 



In one specimen the white colour is replaced by pink. 



Several adult and young examples from Fienerentova. 

 Length 7 inches. 



XIX. — Notes Introductory to the Study and Classification of 

 the Spongida. By H. J. Carter, F.R.S. &c. 



[Continued from p. 40.J 



Part II. Proposed Classification op the Spongida. 



In the general classification of the Spongida there is not 

 much difficulty, as the skeleton (which too often is the only 

 part that reaches us, from the inaccessible places in which 

 many of them grow and the accidental circumstances under 

 which they reach the shore) consists of durable material which, 

 in structure and composition, admits of very easy arrangement ; 

 while where there is no skeleton at all, this alone for such 

 sponges is sufficiently characteristic of the order. 



But in the more particular classification there are peculiar 

 difficulties, inasmuch as there is no expression in sponges as 

 in other animals and in plants ; that is, there is nothing like 

 a calice, as in the coral, and nothing like a flower, as in the 

 plant, to guide us — what there is in this respect, viz. the 

 spongozoon, being microscopic in size, undistinguishably alike 

 and so protean in form as only in its active living state in situ, 

 or just after it has been eliminated from the sponge, di- 

 stinguishable from a common amoeban animal. 



Again, as regards the general form of the sponge itself, there 

 are many instances where the same form may be assumed by 

 totally different species, and the same species assume different 

 forms, so that a microscopical examination of the " proper 

 spicule " can alone determine the species ; thus a fan-shaped 

 and a vase-like form respectively may have at one time the 

 same, and at another a different form of spicule. And yet again 

 the aid derived from the form of the " proper spicule " is con- 

 fined to sponges so provided, while those which have nothing 

 but foreign objects instead of the " proper spicule " are even 



