298 A MONOGRAPH OF THE 



thirds of a line. A few of the pores are visible through an 

 inch lens, but the greater number are very minute. 



The dermal membrane is transparent, and the unispiculous 

 network is a very beautiful object ; the areas are much 

 more frequently triangular than quadrangular, and a con- 

 siderable number of them have each a circular or oval pore; 

 about one in every three or four are thus perforated. The 

 interstitial membranes are but sparingly furnished with 

 spicula. 



There were two other small columnar-shaped specimens 

 in the same collection, one of which may have originally 

 formed part of the large specimen, but the other appears to 

 have been a young one of the same species, although of a 

 short columnar form. This specimen was remarkable from 

 its having the spicula of the dermal network someAvhat less 

 in diameter than those of the skeleton. In the adult speci- 

 men this was not the case ; in all other respects the two 

 agreed exactly in their organization. 



In the young specimen of this species and in parts of the 

 mature one the symmetrically disposed primary lines of 

 the skeleton were strikingly apparent for a considerable 

 depth beneath the outer surface, while in other parts of the 

 surface of the mature specimen they were few and not 

 readily discernible, and had it not been for the more equable 

 character of the network than what Ave are accustomed to 

 see in Halichondria, the sponge might have been readily 

 mistaken for a member of that genus, and especially so if 

 the examination had been confined to the deep-seated 

 portions of the mass. 



A full-sized spiculum measured T y B th inch in length. 



I subsequently received three specimens of this sponge 

 from the trawlers off Hastings. One of them, about the 

 form and size of a dried fig, the other two had assumed 

 the inosculating branched or lobular form; the largest of 

 the two was of an irregular triangular form, each side being 

 about four inches long, and the greatest thickness Avas 

 about ten lines. In the living state the sponge Avas soft 

 and gelatinous to the touch, hut not slimy ; the sarcode 

 Avas very abundant, and it contained numerous minute 



