BRITISH SPONGIAD^. 277 



nial membrane abundantly spiculous, reticulated ; rate 

 unispicular, with numerous dispersed spicula fre- 

 quently intermixed with the reticulations. Skeleton. 

 Reticulations diffused and open or unispiculous ; 

 spicula sub-fusiformi-acerate, small and slender. In- 

 terstitial membranes. Tension spicula, sub-fusiformi- 

 acerate, very slender, few in number. GeramUles mem- 

 branous, aspiculous. 



Colour. — Nut-brown in the dried state. 

 Habitat. — Coast of Scotland, Mr. Peach ; Guernsey and 

 Bantry Bay, Rev. A. M. Norman. 

 Examined. — In the dried state. 



In the Johnstonian collection of British sponges in the 

 British Museum there are four small specimens on one 

 board, labelled Halichondria cinerea. Two of the speci- 

 mens are upon a piece of card marked 1 7°, neither of which 

 is the sponge described by Ur. Grant as Spongea cinerea ; 

 the pieces are of different sizes, and represent two distinct 

 undescribed species, the larger one being the type of our 

 Isodidya Peachii. This specimen is not in a very good 

 state of preservation, but I have fortunately obtained others 

 from Mr. Peach and the Rev. A. M. Norman in very fine 

 condition. The reticulations of the dermal membrane are 

 a very beautiful object ; they are three, four, and sometimes 

 five sided, each side being the length of a single spiculum, 

 but the regularity and beauty of the structure is frequently 

 obscured by the occurrence of large patches of spicula, 

 which are irregularly dispersed over the tissue. These 

 additions to its structure appear to be more especially 

 above those parts to which the skeleton beneath is more 

 strongly adherent. The skeleton is more open and diffused 

 in its structure than is usual in that of an Isodictya ; the 

 sides of the areas having two or three and sometimes more 

 spicula in their length. The spicula of which it is com- 

 posed are minute and very dehcate in their proportions ; 

 they are sub-fusiformi-acerate in form, of an average length of 

 jBiSt inch, and are ^'^rd inch in diameter. These proportions, 



