174 BRITISH SPONGIAD.E. 



4. DJKSMACIDON CONSTBICTUS, Bow., n, 350 ; in, PL 

 LXXI, figs. 310. 



1867 Biemma constricts, Gray. Proc. Zool. Soc., p. 538. 



" When I characterised this species it was from the 

 only specimen that I had then seen of the sponge, a 

 fragment about two inches high, based on the remains 

 of a coral, and so completely waterworn that very few of 

 its specific characters were available for description. 

 Since the completion of Vol. Ill of my ' Monograph of 

 British Sponges ' I received, August 20th, 1874, from 

 the Rev. Mr. Norman a massive sponge of pale brown 

 colour, which he had dredged in "Westport Bay, County 

 Mayo, Ireland. This, on a microscopical examination, 

 proved to be Desmacidon const-rictus in a fine state of 

 preservation. The breadth of the specimen was three 

 inches and a half, the thickness at the summit one inch 

 and a quarter, and it tapered gradually downwards to 

 the length of two inches and a quarter, terminating in 

 a thin blunt basal edge about two inches wide. The 

 form of this specimen is unlike that of the type, but 

 the perfect state of preservation of all its structures 

 enables me to give a more complete idea of its specific 

 characters than that afforded by the first description. 



" The surface in the dried state is slightly rugose, 

 and sections in Canada balsam beneath a power of 

 eighty linear exhibit minute groups, each consisting 

 of four or five spicula, projecting through the dermal 

 membrane so as to cause it to appear minutely hispid. 

 The dermal membrane is abundantly furnished with 

 tension spicula, thickly felted on all parts of its 

 surface ; they are of the same shape and length as 

 those of the skeleton fibres, but not above half their 



