BRITISH SPONGIADjE. 179 



several little areas, nearly free from spicula, and in each of 

 these there were congregated from one to five or six pores, 

 irregular both in size and position. These groups of pores 

 were separated from each other by one or more loose fasci- 

 culations of spicula. The slightly hispid character was pro- 

 duced by the partial projection of portions of these fasciculi, 

 disposed on the sides of the elevated parts of the corruga- 

 tions. A few small groups of pores were visible on the tops 

 of the ridges, but by far the greater number of groups were 

 in the depressed portions of the dermal surface. The oscula 

 were very slightly elevated above the general surface, and 

 their margins were a little thickened and quite smooth. 



The difference in thickness between the skeleton and ten- 

 sion spicula is not so great as it is in some of the nearly 

 allied species, the diameters of the latter being seldom less 

 than about half that of the former. 



The gemmules are of a deep red amber colour, and are 

 filled with minute molecules. They vary in diameter from 

 TSTsth of an inch to ^nd of an inch, but by far the greater 

 number are about intermediate between these figures. 



The colour of this sponge renders it very liable to be mis- 

 taken for Ifalichondria panicea, but a very slight amount of 

 examination will readily separate them from each other. 



Mr. Norman's specimens were found on shelving rocks 

 between high- and low- water marks. 



19Hymeniactdon PERLiivis, Boiverbank. 



Spongia perlevis, Montagu. 

 Halichondria perlevis, Johnston. 



Sponge. Massive, depressed, sessile ; upper surface fur- 

 nished with numerous irregular mammseform pro- 

 cesses. Oscula simple, dispersed. Pores inconspicu- 

 ous. Dermal membrane simple, pellucid, aspiculous, 

 thin. Spicula of the skeleton acuate, sub-fusiform, 

 rarely sub-spinulate. Sarcode abundant. Gemmules 

 membranous, aspiculous, round, or oval. 



