Sponges from South Australia. 371 



Stelospongus Icevis and S. crihrocrusta are so remarkably 

 different that the two cannot come under the same designa- 

 tion, while those of Halispongia choanoides and Stelospongus 

 crihrocrusta are remarkably alike. 



At the same time Dr. Bowerbank, in 1872 (Z. c), evidently 

 connects Halispongia choanoides with Stelospongus loivis, when 

 at p. 123 he says, " the skeletons of what are apparently 

 various species of this genus are very common in collections 

 from Australia," by which he probably meant those of S. 

 Icevis, to which I have alluded as being so durable that their 

 skeletal structure survives the ordeal of the waves in which 

 S. crihrocrusta would go to pieces. 



Again, Hyatt states, with reference to the typical structure 

 of the fibrous skeleton in " Stelospongus,'''' viz. the radiating 

 primary bundles {op. et loc. cit. p. 529), that " there are none 

 of these, properly speaking, in some other species, but only 

 closely connected sheets of parallel primary fibres ; . . .these 

 lead into the genus Spongelia, between which and this genus no 

 definite and constant differences, applicable to all the species 

 without reservation, have been found in the skeleton." How 

 far this may apply to ;S^. crihrocrusta I cannot say, for the 

 other species of Stelospongus which I have described from 

 "Port Phillip Heads " {op. et loc. cit.), viz. S. flahelliformis^ 

 S. latus, and provisionally S. tuberculatus, present respectively 

 ■the crust of S. crihrocrusta, but with much more keratose 

 fibre — especially S.flahelliformis, which, but for the difference 

 in consistence, form, and structure of the fibre, might exter- 

 nally, on account of the crusts being so much alike, be viewed 

 as a specimen of Coscinoderma ; while, on the other hand, the 

 density of the keratose structure and its sand-bearing fibre 

 internally allies it to Stelospongus Icevis. 



Under these circumstances I shall give the following de- 

 scription of Stelospongus crihrocrusta, and leave others to form 

 their opinion of it afterwards. 



Stelospongus crihrocrusta, n. sp. 



General form pear-shaped (the same as that of S. lawis). 

 Colour grey. Surface even, composed of foreign material so 

 arranged as to present a uniform polygonal reticulation in 

 slight relief, whose interstices are diaphragmed by the pore- 

 areas, which consist of a much smaller reticulation formed of 

 sarcode, also charged with foreign material. Vents for the 

 most part very large, single or in plurality, on the summit of 

 the sponge, more or less projected on conical eminences of the 

 general structure, or on a level with the arenaceous crust that 

 extends up to their margin, which is not fringed but even. 



