1SODICTYA. 133 



" Habitat. Westport Bay, Ireland, 5 fathoms ; Rev. 

 A. M. Norman. 



" Examined. In the dried state. 



" I received a considerable number of specimens of 

 this sponge for examination from my friend the Rev. 

 A. M. Norman, who informed me that they were 

 dredged in about 5 fathoms just inside of the Light- 

 house at Westport Bay, Ireland. They were of 

 various sizes, but all of them irregularly massive in 

 form. The largest is two and a half inches in length, 

 one and a half inch in breadth, and three quarters of an 

 inch in thickness ; the smallest one does not exceed 

 half an inch in diameter. They all agree very closely 

 in the dark purple surface colour, and their surfaces 

 are mostly smooth ; but in the two largest the sur- 

 faces are slightly granulated. The dermal mem- 

 brane is furnished with numerous, slender, acerate, 

 tension spicula, which are rather irregularly dis- 

 tributed, being numerously dispersed in some parts 

 and sparingly so in others ; and there are also irregu- 

 larly shaped areas in which there are few or none of 

 them, and in these areas a few open pores were 

 observed. These areas are very characteristic of the 

 species. They are just such as those observable in 

 Isodictya indistincta. The primary lines of the skele- 

 ton vary to some extent in the number of the spicula 

 composing them, but in all they are more or less 

 multispiculous. The secondary lines of the skeleton 

 are numerous and are rather regularly disposed, so 

 that the general form of the skeleton-rete is. to a verv 



<~> ' V 



considerable extent, symmetrical. 



" The tension spicula of the interstitial membranes 

 are not so numerous as they are on the dermal one. 



