6 Mr. n. J. Carter on three Pachytragous Sponges 



bullock's liver." Now, assuming, in accordance with Dr. 

 Bowcrbank's experience, tliat this is the best way to preserve 

 sponges for description, we can hardly think that the colours 

 of the wet were different from those of the dried specimen ; or 

 this would have been noticed. 



Hence, as the species which I have been describing is jet- 

 black wlicn dry, and the body or internal substance inclining, 

 if any tiling, to dirty green, while the same colours are pre- 

 sented by the portions wliich have been preserved in spirit 

 and water, I cannot but infer that at least, as before stated, 

 the black sponge which I have designated by tlie specific 

 name of "w/yer" is a variety of Dercitus BucMandi^ and 

 tliercfore deserving of this separate denomination. 



But wliether the reader chooses to admit this or not, he can 

 hardly fail to see that, cad. par.^ there is a vast difference 

 between the description of a sponge from " the life," and that 

 of one which the author has only seen after death. 



It is not difficult to find this sponge, because it does not grow, 

 like many, on the under surface of the rock, but grows on its 

 sides in deep bowers, souglit for apparently by the sponge 

 for protection from the waves. Then, its black-velvct-looking 

 appearance strikes tlie eye immediately ; but the difficulty 

 of getting at it, except in a more or less horizontal position, 

 and its toughness and firm adlierence, rendering it neces- 

 sary to take off a portion of the rock on which it grows with 

 hammer and cliisel to obtain the whole of the specimen, make 

 its collection by no means an easy task for a stiff old collector. 



Perhaps the most remarkable point, after all, about this 

 sponge is the presence of the celluliferous cortical layer and the 

 characters of the cells of which it is composed — since, by their 

 accumulation here, and being scattered through the substance 

 of the sponge, they, although totally different in composition, 

 do occupy a 2)osition exactly like that of the globular crystal- 

 loids wliich form a crust round and are scattered generally 

 through the substance of the Geodidse. But of this more 

 under " General Observations." 



The puckered state of this sponge on the surface, while in 

 situ^ seems to arise from contraction occasioned by the falling 

 of the tide, or absence of water, when its substance becomes 

 draAvn towards the more prominent points of the rugged por- 

 tion of rock beneath, over v/hicli it may be growing. But, 

 whether this explanation be correct or not, the puckered 

 radiating lines from particular points on the surface of the 

 sponge are remarkable. 



It is also worthy of remark that, although the sponges of 



