Mr. H. J. Carter on Purisiphonia Clarkei. 377 
where the structure is still filled with siliceous grit, but whitish 
grey where it has been emptied by means of acid of the calcare- 
ous material that originally filled this part (Moore, /. c. p. 235). 
Surface undulatory on both sides. Pores, which are organs 
of the sarcode, of course, in like manner, absent. Oscules 
very numerous, averaging }> inch in diameter and about the 
same distance apart, more or less regularly disposed over each 
surface, expanded at the outlet, and bridged over by reticu- 
lated spiculous structure, which divides the subjacent large 
aperture into several smaller ones, and in some instances, 
from its regularity, presents a septate or stelliform figure ; 
followed by their respective canal-systems, which, descending 
vertically and branching out towards the opposite sides of the 
sponge, end just under the surface in the intervals between 
the oscules; thus the excretory canal-systems, connected with 
the oscules on one side, terminate on a level with the oscules 
on the other side of the sponge, and vice versd@, where proba- 
bly, in the living state, the pores of the dermal sarcode opened 
into them: sometimes two systems may be seen, side by side, 
reversed in this way. Internal structure made up of straight 
spiculiferous bundles, averaging half an inch in length, which 
cross each other at different angles in all directions, in the midst 
of minute vitreous reticulation, the whole cemented together 
into a common mass by silicified sarcode, traversed by the 
excretory canal-systems above mentioned. Spiculiferous bun- 
dles composed of fine, smooth, long, linear spicules, arranged 
parallel to each other, and surrounded generally by silicified 
sarcode, or united together in smaller bundles, separately, by 
the silicified sarcode being disposed in the form of transverse 
bars, so as to present a ladder-like appearance. Reticulated 
structure consisting of small sexradiates, united arm to arm 
and to the spiculiferous bundles by the silicified sarcode, 
which is more or less spined throughout, and the spines in 
some instances multifid. Spicules, for the most part, re- 
placed by an axial cavity in the spiniferous silicified sareode, 
which, in many parts of the skeleton, is thus rendered more 
or less continuously canaliculate. Rosette globular, radiate ; 
rays capitate, about 1-3000th inch in diameter. Smallest 
sexradiate seen in the reticulated structure 1-75th inch in 
diameter. 
Hab. Marine. 
Loc. Upper Oolite or Cretaceous system, in boulders with 
marine shells, ‘ not uncommon” (Moore, /. c. p. 235). Wol- 
lumbilla Creek, Queensland, N.W. Australia. 
Obs. As the specimen of Purisiphonia Clarkei above de- 
scribed is so imperfect, I prefer the term “hollow” to that of 
