Sponges from South Australia. 135 



of comparatively small and delicate sagittal quadriradiates, 

 which will be more particularly described hereafter. Wall very 

 thin, not more tlian 1-1 12th inch in diameter, consisting of 

 only two skeletal layers, viz. an external and an internal one, 

 the former composed of the large slightly curved acerates 

 before mentioned, and the latter of the delicate quadriradiates 

 just noticed, which support the soft parts of the species. Spi- 

 cules of two kinds, viz. acerate and quadriradiate : — 1, ace- 

 rates, very large, long, symmetrically fusiform, slightly 

 curved, sharp-pointed at each end, averaging l-12th inch 

 long and 25-6000ths in. in transverse diameter ; 2, quadriradi- 

 ates, more or less sagittal in form, with a long shaft directed 

 longitudinally backwards when in situ, and the two arms 

 expanded laterally almost perpendicular to the shaft, with the 

 fourth arm, which is short and curved towards the mouth, 

 directed inwardly; shaft about 90 by l-6000th in., arm 43 by 

 l-6000th. No. 1 forms a single layer on the surface as before 

 stated, and no. 2 the internal layer also before noticed, with 

 more or less of the arms exserted between the lono- acerates, 

 so as to give this part a minutely hispid appearance. At 

 first sight the latter look like mortar-spicules or small acerates, 

 but although they appear to serve the same purpose, they are 

 not so, but what I have stated. Size of group about 2 inches 

 in diameter at the circumference, contracted to a point at the 

 base. 



Obs. In structure this species is very like Hackel's Ascul- 

 mis armata ('Atlas,' Taf. xiii. fig. 1), but of course very 

 different otherwise. It is remarkable too that the '' granu- 

 liferous nucleated cell " or " Kern " which is so characteris- 

 tically abundant in the Ascones (ex. gr. ClutJirina) should be 

 equally abundant here. 



^65. Aphroceras syconoides. 



Individualized. Long, sessile, round, cylindrical, dimin- 

 ishing towards the mouth, which is truncate, also towards the 

 fixed end, which is contracted ; without peristome. Colour 

 in the dried state whitish grey. Surface consisting of cribri- 

 form sarcode, charged with mortar-spicules, more or less con- 

 cealing subjacent, large, slightly curved, fusiform acerates, 

 arranged longitudinally, parallelly,and in close approximation. 

 Pores in lines, in the cribriform sarcode between the long 

 acerates. Vent single, terminal, naked, leading into a cloacal 

 cavity which is narrow and accords in shape with that of the 

 specimen ; covered with circular sphinctered holes in juxta- 

 position and of nearly uniform size ; echinated with the 



