Sponges from South Australia. 319 



lighter on the less exposed parts, light sponge-colour inter- 

 nally. Surface uniformly covered with low conuli about 

 l-24th in. apart, consisting of a few grains of sand crowning 

 a conical projection of the subjacent fibro-reticulation which 

 supports the black dermal membrane. Pores in the dermal 

 membrane opposite the interstices of the subjacent fibro-reticu- 

 lation. Vents large and numerous at the ends respectively 

 of the mamilliform lobes and on the margin of the more 

 crested parts. Fibre internally small, solid, very uniform in 

 size, without core, reticulated ; traversed vertically by little 

 tracks of sand, held together by a minimum of keratine, 

 which is continuous with the rest of the fibre, and terminating 

 in the conuli mentioned ; interstices of the mass of reticulated 

 fibre tympanized by thin transparent sarcode, which thus 

 gives the parenchyma an unusually wide, cancellated, flimsy 

 structure, which being traversed also by the branches of the 

 excretory canal-systems, produces the very light structure which 

 characterizes the species. Size of the largest specimen, for 

 there are two, 11 in. high by 6 x 2 in. horizontally in its 

 greatest dimensions. 



Hab. Marine. 



Loc. Port Phillip Heads, South Australia. 



Obs. The scantiness of the fibre and its wide reticulation, 

 accompanied by the flimsy transparent sarcode in its present 

 dried state, which tympanizes the interstices, produces an 

 extremely light and loose cancellous texture when dry, which, 

 together with the black colour of the dermis which is equally 

 thin, renders the species almost unmistakable. 



Fam. Pseudohircinida. 



Finally, we have to return to the last family in my orignal 

 classification of the Psammonemata, viz. the Pseudohircinida 

 (see Tabular View, antea p. 215), whose consideration, for 

 reasons already given, was postponed for a more convenient op- 

 portunity, which has now arrived. 



This family was intended for Psammonematous sponges 

 whose sand-grains were accompanied by spicules of species be- 

 longing to one or other of the three following orders : — viz. the 

 Rhaphidonemata, Echinonemata, and Holorhaphidota ; 

 hence the three groups of which the family was composed 

 were named Chalinohircinina, Armatohircinina, and Pseudo- 

 arenosa respectively. 



But it now seems to me that the location of these groups 

 should be determined by the state in which their spicules are, 

 that is, whether they are entire or fragmentary, since, if the 

 former, the groups may be relegated to the orders to which 

 they respectively belong ; and if the latter, viz. fragmentary, 



