CHAP, in.] THE CRUISES OF THE 'PORCUPINE.' ] 13 



bush or shrub, which appears to clothe the bottom 



in some places over a large area like heather on a 



moor. There are at least three species. In one the 



branches are strict and rigid ; while in another the 



arrangement is more lax, side branches coming off 



from a flexible central rachis like the barbs from the 



shaft of an ostrich feather. The branches seem in 



some cases to be from 50 to 80 centimetres in height, 



and the stems near the base are 2 to 3 centimetres in 



diameter. The stem and branches consist of a firm 



central axis, semi-transparent and of a peculiar 



ellowish green colour ; composed of a continuous 



orny substance filled with masses of needle-shaped 



Dicules arranged longitudinally in dense sheaves. 



'his axis is overlaid by a soft bark of sponge sub- 



;ance supported by needle-shaped spicules, and full 



the bihamate e spicules of the sarcode ' so charac- 



eristic of the genus Esperia and its allies. The 



rust is covered with pores, and rises here and there 



to papillae perforated by large oscula. This sponge 



ppears to belong to a group allied to the Espe- 



ada3, and perhaps even more closely allied to 



ome of the fossil branching forms whose remains 



re so abundant in some beds of the cretaceous 



eriod. A still finer species of the same group 



as dredged by Mr. Gwyn Jeffreys in the first 



ruise of the following year. 



Another peculiar sponge (Eig. 13) is very abundant 

 nd of a large size. This form was admirably described 

 y Professor Loven unaccountably under the name 

 ? Hyalonema boreale. It is certainly very far from 

 r yalonema. It is more nearly allied to Tetliya, for 

 he body of the sponge must certainly be referred to 



i 



