ISODICTYA. 133 



" Habitat. — Westporfc Bay, Ireland, 5 fathoms ; Rey. 

 A. M. Norman. 



" Examined. — In tlie 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 hues 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 very 

 considerable extent, symmetrical. 



" The tension spicula of the interstitial membranes 

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



