Sponge-fauna of Norway. 421 



presence or absence of anchoring fascicles appears to me to be 

 of scarcely specific, much less of generic, importance ; indeed 

 I have now before me a sponge which in no detail of gross or 

 minute anatomy differs from Thenea WalUchii {Wyville- 

 Thomsonia)^ except 'that it is entirely devoid of the usual ap- 

 pendages. So far as this character goes, therefore, I see no 

 good grounds for separating FangophiUna from TetWa^ and 

 would therefore reunite them. In that case Tetilla (Sollas) 

 would comprise Tetilla, Sdt., Craniella, Sdt., and Fango- 

 pMlina^ Sdt. ; but it is quite possible that the distinction 

 between Tetilla and Oraniella, asserted by Schmidt, in the 

 absence of a rind in the former genus, does really exist, and 

 that T. cranium has been wrongly included in Tetilla, its true 

 place being with Craniella. But if T. cranium be taken from 

 Schmidt's Tetilla there remain only in that genus T. pohjura^ 

 euplocamus, and radiata, all of which are provided with 

 anchoring tails. By amending the definition of the genus so as 

 to make it include as a character the possession of " tails," 

 all necessity for a new name will disappear, since the residual 

 species of Tetilla, left after the removal of T. cranium^ are 

 just those which Schmidt includes in Fangopliilina. Thus, if 

 Craniella prove distinct from Tetilla, we have, on Schmidt's 

 own showing, 



Craniella + T. cranium =^ Craniella. 



Tetilla— T. cranium=Tetilla=^Fangophilina. 

 It only remains to include Fangophilina sid)mersa in our 

 list of Tetilla, and to add a species of Bowerbank which I 

 had previously overlooked. Continuing from page 161, 

 we have 



14. Tetilla suhmersa, 0. S. Spong. Meerb. Mexico, 1880, 

 p. 73, pi. X. fig. 3. Carib. Sea. 



15. T. unca, Bwk. P. Z. S. 1872, p. 118, pi. v. figs. 7-10. 

 Hammerfest, 150 fms. 



Tetractinellidae, Marshall. 



Externa, Sollas. 



Leptochrota, Sollas. 



Thenea, Gray. 



Thenea WalUchii, Perceval Wright. 



Synonyms. 



1870. Tiniyville-Thomsonia Wallichii, Perceval Wright. 

 „ Stelletta aguriciformis, O. Schmidt. 

 Dorvillia ayaricifonnis, Kent, 



