62 BRITISH SPOXGIAD.E. 



and very slender, acuate; and also long and slender, 

 attenuato-acuate, basally spinous, irregularly dispersed. 

 Internal defensive spicula, attenuato-acuate, entirely 

 and strongly spinous, short and stout, very numerous. 



" Colour. In the dried state, dark amber-brown. 



" Habitat. Birterbuy Bay, Ireland ; Hev. A. M. 

 Norman. 



"Examined. In the dried state. 



" This beautiful and interesting little sponge forms an 

 exceedingly thin patch eight lines in length and four 

 in breadth on the inner surface of a fragment of the 

 shell of a Pecten maxhnus. A small portion of the 

 sponge mounted in Canada balsam exhibited the surface 

 as abundantly and powerfully hispid. Some portions 

 of the sponge were nearly opaque in consequence of 

 the presence of dark amber-coloured sarcode beneath 

 the derniis, while other parts were in a beautifully trans- 

 parent state and exhibited the structural characters of 

 the sponge in a very satisfactory manner, with the 

 strong hispidation of the surface produced by the 

 projection of numerous, internal, defensive spicula, 

 through the dermal membrane for more than half their 

 entire length. As these spicula do not exceed ^^ 

 inch in length, it would appear that the thickness of 

 the sponge in those parts would not exceed about 

 -7T7T inch. 



500 



" The dermal membrane appears to be abundantly 

 supplied with the long and very slender tension spicula, 

 but from the thinness of the sponge and the trans- 

 parency of the dermal membrane it is not easily deter- 

 mined to which part of the sponge the numerous, 

 single, long, and very slender spicula belong ; but 

 this uncertainty does not obtain to so great an extent 



