460 Dr. J. E. Gray on the Classification of Sponges. 



often imbedded in the sponge ; stellate spicules in the sarcode 

 all crowded together. 



A. Sponge shorty gloiose^ with elongate spicules having three 

 acute recurved branches on the outer end^ which support 

 the outer surface^ or extend beyond it. 



* Sponge attached to rocks ^ with an expanded base. 



Fam. 3. TethyadsB. 



The tricurvate spicules extending beyond the outer surface 

 of the sponge. Tethya. 



See Tethya arabica^ Ann. & Mag. N. H. 1869, iv. p. 3, 

 pis. 1 & 2. 



The young, just hatched, of Tethya^ as is proved by Mr. 

 Carter (see this Number, p. 413), is furnished with elongate 

 rooting fibres, which are lost when the animal becomes at- 

 tached. But in certain genera, as Euplectella^ Hyalothaumaj 

 &c., which remain free, these fibres are retained during life ; 

 and it is doubtful if Lophurella^ which is only rather more 

 than a quarter of an inch long, may not be a young specimen 

 in a state of change. 



Fam. 4. Donatiadae. 



The tricurvate spicules supporting the outer surface of the 

 sponge. 



Tethyadse, sect. I.*, Gray, I. c. p. 541. 



Donatia &c. ; add Tethyopsis^ Stewart. 



** Sponge free, with elongate anchoring spicules ending in 

 three or four recurved spines. 



Fam. 5. Theneadse. 



Sponge oblong, with many excretory pores above, with tufts 

 of spicules beneath, and numerous stellate masses in the flesh 

 on the underside. 



Thenea, Gray, P. Z. S. 1867, p. 541,= Tethya muricata, 

 Bowerbank, B. S. fig. 35, and figs. 304 & 305. Dorvillia 

 agariciformis, Kent, Microsc. Journ. 1870. Tisiphonia, Wyv. 

 Thomson ; SteUetta, 0. Schmidt. Wyville-thomsonia Wal- 

 lichii, Perceval Wright, is said to be the young state of this 

 species. 



Fam. 6. Lophurellidae. 



Sponge oblong, with a single excretory pore above, and 



