BRITISH SPONGIAD^. 293 



latter, although of the same length as those of I. densa, are 

 considerably less in their diameter, and in /. densa we do 

 not observe the large irregularly shaped porous areas in the 

 dermal membrane, which are so characteristic in I. indis* 

 tin da. 



The skeleton spicula of /. simido are also of about the 

 same length as those of I. densa, but they are still more 

 slender than those of I. indisfincta. 



The sarcode has been very abundant, and in its present 

 condition is of a dark amber colour. 



13. Isodictya anomala, Boioerbank. 



Sponge. Massive, sessile ; surface even. Oscula few, 

 large, simple. Pores unknown. Dermal membrane, 

 unknown. Skeleton. Primary lines multispiculous, 

 very large and compact ; secondary lines, usually a 

 single spiculum ; spicula inflato-fusiformi-acerate, short 

 and stout. Interstitial membranes. Tension spicula, 

 acerate, slender. 



Colour. Dried, yellowish- gray. 

 Habitat. Torbay, Mrs. Griffiths. 

 Examined. In the dried state. 



The sponge which is the type of the above species is in 

 truth but a fragment, apparently about the eighth part of 

 a mass, having been about the size and form of a large 

 walnut ; or it may have received its curved and somewhat 

 concave form by having partially surrounded the stem of a 

 large Pucus ; it is eight lines in diameter, and does not 

 exceed three in thickness. For the depth of a line and a 

 half from the surface the skeleton is composed of a series 

 of stout parallel primary fasciculi of spicula, connected by 

 secondary fasciculi, usually of single spicula, and poly- 

 spiculous, and the spicula composing them are remarkably 

 stout in proportion to their length, and very variable in 

 their fusiform structure ; the amount of central inflation 



