Sponges from South Australia. 451 



(for there are three of different sizes, but all of the same 

 shape) 4 in. high, 5 in. long, and 1 in. thick, which is the 

 breadth of the flat border or summit. 



Loc. Port Western. 



Ohs. This species is chiefly characterized bj the intensely 

 prickly aspect of the spiniferous acuate, while the smooth 

 acuate, which is confined to the fibre, very much resembles 

 one of the forms assumed by the " tibiella " in the Hali- 

 chondrice. But at present, as I cannot find an undoubted 

 skeletal acuate and there are no flesh-spicules, I can only 

 place it among the Halichondrue provisionally. 



Halichondria stelUderma (incertee sedis) . 



Specimen subglobular, bicornute, growing round the small 

 stem of a Gorgonia, imbedding at the same time much foreign 

 material together with the spicules of the Gorgonia. Con- 

 sistence soft, resilient. Colour grey. Surface uniformly 

 scattered over with small cones rising out of a general, fibro- 

 reticulate, dermal structure, which, together with the opacity 

 of the conical eminences, gives the stellate appearance of 

 which the latter form the centres of the stars respectively ; cones 

 about l-24th in. in diameter at the base, about the same height, 

 and about twice this distance apart, surmounted by a single 

 short filament of the internal fibro-skeletal structure. Pore- 

 areas occupying the interstices of the dermal fibro-reticulation. 

 Vents mostly large, sparsely scattered over the surface, one 

 at the end of each horn-like process of the body, each provided 

 with a strong sphinctral sarcodic diaphragm. Internal struc- 

 ture loose, consisting from without inwards of a thin skin 

 followed by large subdermal cavities opening into " fold- 

 bearing" ? excretory canals, which traverse plentifully the 

 body-substance and end in the vents mentioned, the sar- 

 code being supported on a reticulated spicule- fibrous structure 

 whose circumferential filaments terminate in the summits 

 of the cones, also as above mentioned. Spicules (which, 

 from their smallness and delicacy, cannot be distinctly seen 

 until a minute fragment of the sponge has been mounted 

 in balsam and placed under the microscope) of two kinds, viz. 

 skeletal and flesh-spicules. Skeletal spicule very slender, 

 smooth, almost cylindrical, slightly inflated at each end, 40 

 by ^-GOOOth in. ; flesh-spicule a very minute equianchorate, 

 whose shaft is so curved that it looks almost equal to half a 

 circle, and of whose three flukes the two lateral ones are 

 spread out almost at right angles to the head ; about 

 2|-6000ths in. long, but so fine that it can hardly be seen 



