9492 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 
living condition this Sponge would probably exhibit a smooth mem- 
branous surface; but in its present state we have large cpen areas 
exhibited in lieu of the smooth dermal membrane. These areas are 
in fact the distal ends of the intermarginal cavities, and are usually 
much larger than the interstitial spaces immediately beneath them. 
In the specimen under consideration, as in similarly organized recent 
Sponges, the proximal terminations of the intermarginal cavities 
communicate immediately with the distal ones of the interstitial 
spaces, and then, uniting, increase in their size as they progress to- 
wards the inner parictes of the great cloacal cavity of the Sponge, 
into which they finally discharge their streams through the oscula. - 
In this organization they closely resemble the structures in the recent 
genera Grantia and Verongia, and many of the fistular keratose 
Sponges of the West-Indian seas. 
I have not detected any connecting spicula; and I have assigned 
the angulated sexradiate ones to the interstitial cavities on the faith 
of some very dilapidated remains of them, deeply immersed in the 
tissues, and rendered visible only by the penetrating power of the 
Lieberkiihn. 
The nearest relations to this tribe of Sponges among the fossil ones 
are decidedly the siliceo-fibrous Sponges of the Flamborough Chalk ; 
and below that formation I am not aware of any such Sponges hay- 
ing been found. The matrix of the Australian fossil also possesses 
much of the character of Chalk; it dissolves completely in dilute 
hydrochloric acid, and leaves only a small quantity of sandy 
residuum. 
I may also observe that the similarity of form and structure be- 
tween the Australian and the English Chalk Sponges in this case is by 
no means a new fact, as there are abundant instances of similar 
close alliances existing among the recent Australian Sponges and 
those of the Chalk-formation of Hngland; and among the most 
prominent are the existing representatives of Choanites and Ven- 
triculites—J. 5. B.] 
2, CRISTELLARIA CULTRATA, Montfort, var. RADIATA, Moore. 
This shell, of which I have discovered but one example, possesses 
the central disk of C. cultrata, from which the ribs on the surface 
proceed ; and although the keel is less produced, there appears no 
doubt it must be referred to this species. From the more radiating 
character of the costs, I propose for the variety the name of C. ra- 
diata. tis from Wollumbilla. 
3. CRISTELLARIA ACUTAURICULARIS, Ficht. & Moll, var. LoneicosTara, 
Moore. 
Shell oblong, moderately biconvex, later chambers passing be- 
yond helicoid portion; surface with ribs which are longi‘udinally 
costated. 
The typical European forms of C. acutawricularis, which are found 
also with this shell, possess smooth surfaces, and are without the 
longitudinal coste,—the difference being so marked as to justify 
