41 



I am couteut to use for the larger groups of Sponges names 

 which are better defined by the contents of the group than by 

 auy form of words." The author adds in a note: — »There is 

 no coucrescence in Placina, and it is absent from species of Te- 

 tilla, but these are the simplest merabers of the order; the Suberites 

 and Tethyidae are Corticate Sponges and without concresceuce, 

 while all Corticate Tetractinellida present this character." 



It seems almost useless to point out that after the researches 

 of Dendy a. o. the absence or presence of Sollas's membrane can 

 never have a classificatory value. Suppose Sollas's membrane did 

 exist — what we emphatically deny — where should then e. g. 

 Halichondria panicea find its place in which Dendy finds »the 

 best example .... of Sollas's membrane". Cf. p. 44 of this paper. 

 1889. Bidder, George, Preliminary Note on the Physiology of 

 Sponges. In: — Proc. Cambridge Philos. Soc. Vol. VI. 

 »The collars in this sponge (viz. Leuconia aspera) unite, so as 

 to interpose a coutinuous membrane between the afFerent and 

 efferent systems ; . . . . 1 believe that this is a mechanism for the 

 filtering of food from the water; the latter permeating or per- 

 colating through the membrane , the food being retained in a 

 position adapted for its ingestion into the bodies of the collar- 

 cells which surround it." 



1889. Dendy, Arthur, Studies on the Coraparative Anatomy of 



Sponges. II. On the Anatomy and Histology of Stelospongus 



flabelliformis, Carter ; with Notes on the Development. In : 



— Quart. .Journ. Mier. Sc. Vol. XXIX p. 325—358. PI. 



XXXIII. Vide pp. 342—345. ') 



... »it has been my good fortune to be able to demonstrate, 



beyond the possibility of a doubt , the existence of this connec- 



ting membrane, which I propose to call Sollas's membrane, in 



Stelospongus". Dendy could as little as Sollas detect flagella, 



these » being entirely shrivelled up , or possibly retracted, when the 



1) The paper was apparently written before the (Jhallenger Report of Sollas came 

 under the authors eyes. Sollas's monograph however is published in 1888 and Dendy's 

 paper only in 1889. 



