376 Mr. H. J. Carter on 



remarkable as it is unusual ; but I have already alluded to 

 the extreme smallness of these in the other specimens of Mr. 

 Wilson's ChalincB {ih. p. 284), and here they are altogether 

 absent, while the fibre is only cored by a flocculent substance 

 such as appears in the transparent fibre of the Psammone- 

 MATA. 



Acervochalina claviformis^ n. sp. 



Erect, cylindrical, clavate or pyriform, with the largest end 

 uppermost. Consistence remarkably loose and tender. Colour 

 grey-brown. Surface uniformly smooth, covered with a fine 

 fibro-reticulation. Pores in the interstices of the reticulation. 

 Vents numerous, very large and circular, with prominent or 

 raised margin, scattered irregularly over the surface. Struc- 

 ture remarkably loose, composed of fibres cored with the 

 spicules of the species, many of which project through the 

 sides, supporting the sarcode abundantly traversed by large 

 excietory canals which terminate respectively in the vents 

 mentioned. Spicule of one form only, viz. acerate, smooth, 

 curved, fusiform, sharp-pointed, about 40 by H-6000th in., 

 coring the fibre and more or less projecting through it. Size 

 of specimen (of which there are two almost exactly alike, 

 although coming from different localities), 5 in. high, 1^ in. 

 in diameter in the widest part of the head, and 5-8ths at the 

 base, where it expands into a discoid root-like attachment. 



Loc. Port Phillip Heads and Port Western. 



Ohs. This species, in the present instance, is chiefly charac- 

 terized by its pyramidal erect form, large vents, and delicate 

 structure, so that, if handled roughly, it would go to pieces. 



Order V. ECHINONEMATA. 



Plumohal{c]io7idria ])lumosa^ YSiX. purpurea, n. var. 



Fig-shaped, the largest end upwards, growing on a frag- 

 ment of the calcareous test of a Polyzoon. Consistence firm. 

 Colour pinkish purple. Surface even, minutely reticulated. 

 Pores in the interstices of the reticulation. Vents small, 

 scattered over the summit. Structure compact; dermis 

 pinkish, but internally light sponge-yellow, composed of 

 sarcode supported on the spiculiferous fibre of the species, 

 traversed by the canals of the excretory system. Spicules of 

 two kinds, viz. skeletal and echinating : — 1, skeletal spicules 

 of two forms, viz. acuate, curved, scantily spined but chiefly 

 towards the large end, about 45 by 2-6000ths in. ; and acerate, 

 smooth,, curved or nearly straight (viz. the " tibiella"), more 

 or less gradually pointed : 2, echinating spicule clavate, thickly 



