SPONGES. 319 



firmer. The interior is full of channels. The spicula 

 here are very varied and interesting, comprising some 

 curious and unusual forms. Some, indeed, are simple 

 needles, nearly straight, pointed at one end rather 

 abruptly. The following are minute. There are a 

 number of rings interrupted at one side, like the letter 

 C, some thicker and more elliptical, others slender and 

 rounder, C- A few take the form of the letter S, but 

 having one lobe much more developed than the other. 

 Some of the C form have both the extremities bifid, and 

 the points widely diverging; and some of these have 

 the back straight, instead of curved, and these with 

 their bifid points, look, when viewed in front, like 

 double anchors. All are, as usual, spun out of the 

 most brilliant glass. 



Then we have in some abundance a sort 1 with firm 

 cartilaginous walls, about one-eighth of an inch thick, 

 standing up to the height of three-fourths, with rounded 

 summits, running in irregular sinuations and convolu- 

 tions, not unlike the cartilage of the human ear, enclos- 

 ing deep hollows. The colour is opaque white, tinged 

 with red, probably from the red mud, which is prevalent 

 here. When cut with a knife this sponge has a sharp, 

 crisp, gritty feel, and when a little is crushed between 

 glass plates we distinctly hear a creaking sound. 



1 Leuccmia nivea. 



