20 A MONOGRAPH OF THE 



cylindrical, nearly as long as the sponge ; armed in- 

 ternally with spiculated, equiangular, triradiate spicula ; 

 spicular ray attenuated. Mouth of the cloaca armed 

 with a thick ciliary fringe, of very long and slender 

 acerate spicula ; base of the fringe supported by large, 

 short and stout, fusiform, acerate spicula. Oscula 

 simple, very slightly depressed from the surface of the 

 cloaca ; as numerous as the interstitial cells. Pores 

 inconspicuous. Interstitial cells, distal terminations 

 more or less obtusely conical ; furnished with a ciliary 

 fringe of slender acerate spicula. Skeleton spicula 

 equiangular triradiate. 



Colour. Cream white. 



Habitat. Coasts of Great Britain, parasitical on fuci, 

 littoral to 8 or 10 fathoms, or more. 

 Examined. Alive. 



This beautiful and interesting little sponge is frequently 

 found associated with Grantia compressa on fuci, either 

 littoral or dredged eight or ten fathoms deep. In the open 

 sea or in littoral localities it seldom exceeds about live 

 eighths of an inch in length, but in tidal rivers, and under 

 some other peculiar circumstances, it attains much larger 

 dimensions. Dr. Johnston, on the authority of the late 

 Professor Edward Forbes, figures it (plate xx, fig. 4, 

 ' History of British Sponges') three inches in length and 

 three fourths of an inch in diameter, and I have specimens 

 dredged in the Ipswich river, by Dr. W. B. Clarke, two and a 

 half inches long and half an inch in diameter. These 

 great dimensions are evidently cases of excessive develop- 

 ment, and in the sponges for which I am indebted to Dr. 

 Clarke are probably produced by the large amount of 

 nutriment derived from the drainage of the populous town 

 of Ipswich. 



In the living condition the surface of the sponge, when 

 examined with a lens of two inches focus, appears to be 

 completely covered with minute conical papillae, from which 

 a few slender sharply pointed spicula are projected. When 



