418 THE DEPTHS OF THE SEA. [CHAP. vn. 



other impurities thus removed, when the skeleton 

 comes out a lovely lacy structure of the clearest 

 glass. The six-rayed form of the spicules gives the 

 network which is the result of their fusion great 

 flexibility of design, with a characteristic tendency, 

 however, to square meshes. 



On the 30th of August, 1870, Mr. Gwyn Jeffreys 

 dredged in 651 fathoms in the Atlantic off the mouth 

 of the Strait of Gibraltar an exquisite sponge, 

 resembling Holtenia in its general appearance, but 

 differing from it in the singular and beautiful cha 

 racter of having a delicate outer veil about a centi 

 metre from the surface of the sponge, formed by the 

 interlacing of the four secondary rays of large five- 

 rayed spicules, which send their long shafts from that 

 point vertically into the sponge body (Fig. 65). The 

 surface of the sponge is formed of a network of large 

 five-radiate spicules, arranged very much as in Hol 

 tenia ; but the spicules of the sarcode the small 

 spicules which are imbedded in the living sponge-jelly 

 are of a totally different form. A single large 

 ' osculum ' opens, as in Holtenia, at the top of the 

 sponge, but instead of forming a cup uniformly 

 lined with a netted membrane, the oscular cavity 

 divides at the bottom into a number of branching 

 passages as in Pheronema anna, described by Dr. 

 Leidy. I was inclined at first to place this species 

 in the genus Pheronema, but Dr. Leidy 's descrip 

 tion and figure are by no means satisfactory, and 

 may refer to some other form of the Holtenia group. 

 The spicules of the ( beard ' are more rigid and thicker 

 than those of Holtenia, and scattered among them 

 are some very large four-barbed grappling hooks. 



