206 Mr. H. J. Carter on 



pan i zed by the dermal membrane. Pores in the interstices of 

 the retiform incrustation. Vent single on the summit, large 

 and circular, about f in. in diameter at the orifice, con- 

 tracted inwardly by a thick, sarcodic, fleshy fold of the 

 dermal membrane. Main fibre cored with foreign microscopic 

 objects, sand, &c. ; lateral or interuniting fibre cored only 

 with the grey flocculent substance, the former psammonema- 

 touSj the latter lujfarid, both enclosed within the same kind 

 of amber-coloured keratine. Sarcode of the interior thick 

 and inspissate, scantily charged with foreign material ; grey 

 in colour, supported by the fibre just described, and traversed 

 by the branches of the excretory canal-system, which open 

 into a general or cloacal cavity terminating in the vent at the 

 summit. Size of specimen 2% in. high by 2\ in. in dia- 

 meter at the base, which is circular. 

 Bab. Marine. 



Loc. Port Phillip Heads, South Australia. Depth ? 

 Obs. While the presence of the luftarid " interuniting 

 fibre " seems to ally this species to the Ceratina, the large 

 wrinkled surface covered with the reticulated or cribriform 

 incrustration, the single large terminal vent preceded by the 

 cloaciform interior, and the fleshy character of the sarcode 

 about the vent, equally ally it to Halispongia choanoides , 

 Bk.,= Stelospongos, Sdt., and especially to the "wrinkled" 

 surface of that specimen respresented and described by Dr. 

 Bowerbank in the ' Proceedings of the Zoological Society ' for 

 1872 (p. 123, pi. vi.) under the name mentioned. Hence my 

 generic appellation should be considered " provisional." 



As the " granulo-tiocculent grey substance " which charac- 

 terizes the core of the fibre in the Ceratina appears to me to 

 be the same as that within the keratose cell ("horn-cell"), 

 and may often be seen mixed up with the foreign objects 

 which form the core of the fibre in the Psammonemata, it 

 seems to me not improbable that this is the substance which 

 first of all brings the foreign material into line for the forma- 

 tion of the fibre in the latter ; and that, failing to do this, the 

 " grauulo-flocculent substance " alone remains, which leads 

 to the production of the genuine fibre of the Ceratina ; while 

 this failure taking place partially, may produce the mixture 

 which is characteristic of that family of the Ceratina for 

 which I have proposed the name of " Pseudoceratida." 



Order III. PSAMMONEMATA. 



As an examination of Mr. Wilson's specimens has sug- 

 gested to me much that indicates a necessary revision of this 

 order, and I find that it can be done best by beginning with 



