PLATE LXX1I. 187 



Habitat. Jersey ; Rev. A. M. Norman. 



Examined From spirit. 



I have seen only one specimen of this species. It 

 was dredged at Jersey in 1867 by the Rev. A. M. 

 Norman. It is parasitical on a slender fucus which it 

 envelopes entirely. It is two and a quarter inches in 

 length, ten lines in breadth, and its greatest thickness 

 is seven lines. The surface is smooth, and the mass 

 of the sponge very firm and fleshy. There are several 

 oscula on each of the broad surfaces of the sponge, 

 none of them exceed a line in diameter. 



The spicula in the dermis are so abundant and so 

 closely felted together as to render their form in situ 

 undistinguishable. In some parts of the dermis the 

 porous areas are tolerably numerous, while in other 

 parts there are few, and the intervening spaces are 

 considerable. 



In the skeleton the same profusion of spicula that so 

 strongly characterises the dermis is observable ; they 

 cross each other in every possible direction, and from 

 their stoutness and great number they render the 

 sponge almost as firm and solid as either H. suberea, 

 ficus, or carnosa. This strength and solidity of cha- 

 racter renders this species readily distinguishable from 

 any of the other British species among their congeners 

 in the first section of the genus Hymeniacidon. 



In many species of Hymeniacidon, although the 

 whole of the spicula are of the same form a great 

 number of them are much more slender than the others, 

 and represent the tension spicula on the interstitial 

 membranes in other sponges, but this is not the case 

 in the species in course of description, in which the 

 whole of them are of the same degree of length and 

 stoutness. 



HYMENIACIDON EADIOSA, Bowerbcmk. 



Plate LXXII. 

 Sponge massive, sessile, firm and fleshy, surface 



