) 



24 Mr, II . J. Carter on the 



nation of his preparations is that, here and there, these spicules 



present a short, thick, conical process or spur, which seems to 



be the equivalent of a ray, and that, if the whole of the spicule 



could be seen at once, it is not improbable that it would be 



found to be a colossal tri- or quadriradiate, whose arms are 



diverted from their usual arrangement when free to that whicl 



is required of them when forming the axis of reticulated fibre ; 



for certain it is that the presence of calcisponge triradiates and 



the " pitchfork-like spicules' 7 with these colossal spicules do 



so far identify them with existing species that, as l)r. Hinde 



has show r n in this remarkable discovery (No. 14, pi. xii.) , there 



can be no doubt as to their original nature, however different 



the colossal spicule may render the Sestrostomellce from any 



thing that has hitherto been shown to exist in the Calci- 



spongias of the present day. Still I think that I .shall be able 



to show hereafter, by the description of a new species of Calci- 



sponge from the south-west coast of Australia, that the prin- 



ciple of this spiculation still exists, if not traceable, already in 

 H ackel' s "colossal 77 spicules. To the crenulated structure 

 which immediately surrounds the colossal shaft in Sestrosto- 

 mella (No. 14, pi. xii. figs. 1 and 2) I shall return presently. 



Meanwhile I would call the reader's attention to a little 

 cylindrical fossil from Farringdon, which in my u Note" on 

 these sponges (No. 11, p. 434) I briefly described under the 

 idea that it was a" calcified Lithistid," but which, it will soon 

 be seen, turns out to be a species of Scypkia (PL I. figs. 1-3) 

 ? 8. cylindrical var. baculata, Quenstedt (No. 7, Taf. cxxiii. 

 fig. 11), allied to Sestrostomella inasmuch as its fibre is pro- 

 vided with a colossal axial spicule bearing here and there a 

 short conical piocess or spur in concentrically laminated fibre 

 (fig. 9, a, £, &c.). Unfortunately, however, the fibre here is 

 not in such a good state of preservation as that of Dr. H hide's 

 Sestrostomella ntgosa ) but sufficient remains to show that it 

 presents a Lithistid aspect (fig. 4), although the many-armed 

 spicules of which it is composed were not naked as in a Lithistid, 

 but surrounded by the concentrically laminated fibre to which 1 

 have just alluded, like the siliceous envelope which similarly 

 forms the fibre of a Hexactinellid (fig. 6, a, Z>, &c), — moreover 

 that the colossal axial spicules often present here and there, 

 and apparently without any regularity in size or distance, a 

 short conical arm or spur like those of Sestrostomella (figs- 5, 

 7, 9, &c.), that the outlines of their surface as seen in the sec- 

 tion may be even or crooked or crenulated (figs. 7-12, &c), 

 and that the spur itself is sometimes sparsely covered with 

 short vertical spines (fig. 5) — also that the sheath or concen- 

 trically laminated fibre enclosing these colossal spicules may 



