BRITISH SPONGIAUiE. 57 



retentive spicula same as those of the dermal mem- 

 brane, few in number. 



Colour. Alive ; dried, nut brown. 

 Habitat. Guernsey, Rev. A. M. Norman. 

 Examined. In the dried state. 



The sponge in its present condition is three inches in 

 height by about two inches in its average diameter ; at 

 about two thirds of its height, it divides into two large 

 rudely conical lobes, terminating obtusely, each being 

 about an inch in height. My friend the Rev. A. M. Norman 

 informed me that when fresh from the sea it was very 

 much larger than it is in its dried condition ; that it was 

 very ponderous and fleshy, and it was with great diffi- 

 culty he succeeded in drying it, in the course of which 

 operation it was exceedingly fetid. The dermis has a 

 dense appearance in consequence of the abundance of the 

 dark purple coloured sarcode with which it is lined, and the 

 profusion of spicula embedded in it. The tension spicula 

 are very numerous, irregularly disposed, and cross each 

 other in every direction. They are rather less in diameter 

 than those of the skeleton, but in every other respect they 

 closely resemble them. The retentive spicula are remark- 

 able from the paucity of spines at the middle of the shaft, 

 so that in many instances they very closely simulate the 

 rotulate form ; they are exceedingly numerous and very 

 minute, requiring a microscopic power of 700 or 800 

 linear to render them distinctly to the eye. The attenuato- 

 stellate spicula, although small, are very much larger than 

 the elongo-stellate ones. The connecting spicula vary con- 

 siderably in size, but when fully developed they are large 

 and strong, but rather short in the shaft ; the recusations 

 of the furcations of the apices of the radii of the expando- 

 ternate terminations are usually at the bases of the forks, 

 and they are abruptly and strongly produced. When per- 

 fectly developed, these spicula are symmetrical in form, but 

 they are subject to frequent malformations of the radii. 

 The interstitial membranes are very abundant, and the 



