32 THE VOYAGE OF H.M.S. CHALLENGER. 



seen that this genus cannot be adopted. The best thing that could be done would 

 consist in a total disuse both of Oligoceras and Hircmia. 



Finally, as to the Ceratelladse, I regard their nature as sponges insufficiently proved to 

 speak here of their place in the system. The late Dr. Gray/ to whom we owe the first 

 description of these interesting beings, though classing them among the sponges, did so 

 with the greatest reserve, " until their organisation and growth is known. At the same 

 time," he adds, "I know no group of sponges with which they can be compared" {loc. 

 cit, p. 576). In his paper on the "Transformation of an Entire Shell into Chitinous 

 Structure," " Carter comes to the conclusion that the Ceratelladse have absolutely nothing 

 to do with sponges. He adopts both the genera distinguished by Gray in his family of 

 CeratelladEe, but he groups them in that of Hydractinise. Hyatt ^ is again of quite a 

 difierent opinion on the matter. He considers the forms in question to be indubitable 

 sponges, and, rejecting Gray's genus Deliitella, unites all the Ceratellada^ known to him in 

 the single genus Ceratella. Now, so far as my own information goes — and like that 

 of the naturalist before mentioned it is limited to the properties of the skeleton 

 exclusively — I must confess that I can only agree with Mr. Hyatt. There is really in 

 the skeleton of Ceratella nothing hydroid or coral-like ; " on the contrary, the whole is 

 thoroughly sponge-like." But this opinion can only be scientifically endorsed after an 

 investigation of the structure of the soft parts of the animals in question, and, until we 

 are acquainted -ndth their internal organisation, any discussion as to their systematic place 

 would be premature. 



Family Aplysinid^. 



Apart from the genus Dendrosjjongia, Hyatt, which, if really to be adopted as an 

 independent genus, may belong to the Darwinellidae, the family in question contains the 

 genera Luffaria, Verongia, and Aplysina. 



Lvffaria. 



This generic name originated with Duchassaing de Fonbressin and Michelotti,^ who 

 have described under this designation numerous sponges from the Caribbean Sea. How 

 far these sponges really belong to Luffaria, and not to Verongia or even Aj^li/sina, is 

 very difiicult to say, the descriptions of these authors being very superficial. As a matter 

 of fact, it must be stated that they regard the Spongia Jistnlaris, Linue- — illustrated in 

 Esper's Pflanzenthiere (Bd. ii. pis. xx., xxi., xxIa.), and the specimen represented on 

 pi. XX. is still in the Museum of Erlaugen — as belonging to their newly-created genus 



' Proc. Zool. Soc. Lond., 1868, p. 575. ^ Ann. and Mag. Nat. Hist., ser. 4, vol. xi. p. 1. 



3 Eeyision, &c., ii. p. 550. < Spongiaii'es, &c., p. 59. 



