Sponges from South Australia. 503 



" nuclei " (Kerne) of his " syncytium " {op. cit. ' Atlas,' 

 Taf. i. fig. 3). Spicules of two forms, viz. triradiates and 

 quadriradiates, the latter in very subsidiary quantity. Tri- 

 radiates comparatively small, variable in form and size, but 

 chiefly equiarmed and equiangled. Quadriradiates about the 

 same size. Ray of the largest triradiates on the surface about 

 30 by 4i-6000ths. The latter composing the skeletal struc- 

 ture of the tubulation generally, the former sparsely scattered 

 throughout, but most numerous about the " spurious vents," 

 apparently without any particular position, as the fourth arm 

 appears here and there, both inside and outside the wall of the 

 tubulation, and the same about the cylindrical prolongations 

 or spurious vents. Of this species there are four specimens, 

 the largest of which is compressed and somewhat triangular 

 in shape, 1|- inch high by 2 x ^ horizontally at the upper 

 border. 



Obs. This is evidently a representative of the Clath- 

 rina which grows so abundantly on the under surface 

 of rocks in this neighbourhood^ viz. Budleigh-Saltcrton 

 (' Annals,' 1884, vol. xiv. p. 18) ; but as there appear to be 

 no rocks at the sea-bottom in Australia, where it was dredged, 

 it grows on shells or the agglomerated material of these parts. 

 Moreover, it difiers from the Clathrma of this place, in which 

 the cylindrical prolongations on the surface are in direct con- 

 tinuation with the interior of the tubulation, like that of 

 the next species that will be described, while in C. cavata 

 they are onlg in communication with the dilated p)arts of the 

 interspaces. « 



We have evidently here a foreshadowing of the vent and 

 cloaca, which are more perfectly developed in 0. tripodifera 

 and following species. 



It belongs to Ilackel's Ascoues of course, and seems, but 

 for the presence of the spurious vents, to be almost identical 

 with his Ascetta dathrus [op. cit. Atlas, Taf. iv. figs. 1-3). 

 As for the difference in spiculatlon which the presence of the 

 quadriradiates makes in Hackel's classification, this may be 

 cancelled under the view that it is a " connective variety," 

 like his Ascetta primordialis (vol. ii. p. 17). 



2. Clathri7ia osculum. 



Individualized, social. Globular, stipitate, presenting on 

 the summit a short, cylindrical, hollow process, and ending 

 below in one or more filiform stems fixed to the object on 

 which it has grown, composed throughout of a mass of tubu- 

 lated thread-like filament growing by almost infinite and 

 irregular branching and anastomosis into the form above 



