Mr. H. J. Carter on known Fossil Sponges. 289 
sent me from the neighbourhood of Port Phillip on the south 
coast of Australia, first represented by Dr. Bowerbank 
(B.S. vol. i. fig. 237) and subsequently called “Zelapia 
australis” by Dr. Gray (Proc. Zool. Soc. 1867, p. 557). I 
have said “ species ” because the upper part of the specimens 
which Mr. Bracebridge Wilson sent me (‘ Annals,’ 1886, 
vol, xviii. p. 148) bore a close resemblance to the heads of 
Sestrostomella represented by Dr. Hinde, as well as to those 
of a fossil group from the Jura which Prof. Zittel kindly sent 
me, in which, in microscopic slices, I also found the form of 
spicule mentioned; all of which demonstrates the accuracy 
of Prof. Zittel’s observations. 
I wish also to note here that, although I have considered 
Dr. Sollas’s “ Pharetrospongia Strahani” (Quart. Journ. 
Geol. Soc. May 1877, p. 242), from which Professor Zittel 
has taken the name of his third family of this order, viz. 
“ Pharetrones,”’ among his Calcispongiz (‘ Handbuch,’ p. 189), 
to be a siliceous sponge like an Australian species of Reniera 
(Monaxonia) whose spicule Dr. Sollas has introduced among 
his illustrations for comparison (op. et loc. cit. pl. xi. figs. 11 
and 12), yet from subsequent facts which have come to my 
knowledge,—such asthe existence of a Calcisponge with thesame 
kind of fusiform, sharp-pointed, acerate spicule, viz. Leucyssa 
spongilla, Heck. (‘ Die Kalkschwimme,’ Bd. i. p. 137, Atlas, 
Taf. xxv. figs. 11-13), evidently designated after the character- 
istic spicule of Spongilla (although it should be also stated that 
the spicule of Leucyssa spongilla is not curved as in Spongilla 
and Pharetrospongia Strahant, &c., but straight, still it is the 
only form of spicule in this sponge) ,—together with the state- 
ments of Dr. Hinde (Cat. Foss. Sp. B. M. pp. 202, 203) in 
support of Prof. Zittel’s view that Pharetrospongia Strahant 
was a Calcisponge, I must now yield to their opinion, who 
for a while made the study of fossil sponges their special 
object. 
Thus, in conclusion, I have given a short sketch of the 
known history of sponges in time and space from the earliest 
geological periods up to the present day, among which we 
notice the absence of any fossil representative of the Horny 
Sponges, which are now so abundant and whose fibre in many 
instances (ex. gr. Luffaria) is almost entirely composed of . 
spongin, which, in elementary composition, as shown in the 
first part of this paper, only differs from chitin (the elytra 
of insects) in quantity, while the quality of resistance would 
appear to be in favour of the former; and yet fossilized 
insects have been handed down to us in almost every geolo- 
Ann. & Mag. N. Hist. Ser. 6. Vol. iv. 20 
