Sponges fi'om South Australia. 131 



irregular triradiates Avitli long shafts, especially on the out- 

 side, where they extend inwards from the other two arms which 

 are fixed in the spicular structure of the surface. Spicules 

 of two kinds, viz. acerate and triradiate ; no quadriradiates : — 

 1, acerates of two forms, viz. one tine, long, straight, cylin- 

 drical, and glistening, and the other stout, much shorter, 

 fusiform, and sickle-shaped ; 2, triradiates, regular and irre- 

 gular, with long shafts but not particularly large. No. 1 in 

 its fine form is confined to the peristome and the composition of 

 the conical spines of the surface, which are about 200-6000ths 

 long, 300-6000ths apart, and 90-6000ths in. in diameter at the 

 base, where their spicules are sunk into the outer part of the 

 wall ; and the other or stout form, which consists of a thick 

 acerate that is much shorter than the " cones " and curved 

 towards the mouth, plentifully scattered among thera, where its 

 largest portion is outside and the other or more attenuated 

 one is sunk into the outer portion of the wall-structure ; no. 2, 

 the triradiates, occupy the position mentioned, including the 

 surface of the cloaca, which possesses no quadriradiates, 

 and therefore presents no spines or " fourth arms " on its 

 surface. Size of largest specimen, for there are several, 

 about ^ inch high by j inch in its greatest diameter. 



Ohs. This is a very remarkable species on account of the 

 glistening cones, composed of spicules like those of the peri- 

 stome, which are scattered over the surface in the midst of 

 large sickle-shaped acerates which do not glisten, and there- 

 fore by their colour, as well as by their form, produce a 

 mixture and a contrast which renders this sponge unmistak- 

 able; while the cones from their prominence, whiteness, 

 large size, pointed ends, abundance, and almost perpendicular 

 arrangement on the surface so remind one of the echination 

 of a " hedgehog," that the latin name of this animal has been 

 used for its specification. The cloaca here also is covered 

 with a delicate layer of clathrous sarcode. 



32. Leuconia nivea, var. australiensis. 



Individualized or agglomerated. Globular, sessile, and 

 solitary, or massive, agglomerated, flat, and spreading. Colour 

 whitish outside, sponge-brown within. Surface consisting of 

 cribriform sarcode, more or less charged with mortar-spicules, 

 knitting together large, more or less sagittal triradiates, with 

 centre so much elevated that they present a tripod-form, whose 

 extended arms thus bind down the surface to a common level. 

 Pores, the holes of the cribriform structure more or less 

 grouped into distinct areas, which occupy the intervals between 



y 



