Catalogue of Non-Calcareous sponges. 231 



Family AXINELLID^E. 



Skeleton typically non-reticulate ; consisting of ascending 

 axes of fibres from which arise subsidiary fibres radiating to 

 the surface. Fibres typically plumose. Megascleres typically 

 stylote but ranging to oxeote. Microscleres rarely present, 

 never chela?. 



Genus Hymeniacidon, Bowerbank. 



Skeleton reticulate, with or without well-defined spiculo-fibre, 

 not plumose. Megascleres styli or subtylostyli. No microscleres. 

 . Von Lendenfeld's genus Stylotella, placed by himself amongst 

 the Heterorrhaphidaj and by Topsent amongst the Esperellime, 

 is clearly not distinguishable from Hymeniacidon, even when 

 the latter is employed in the restricted sense of the Challenger 

 Report. 



Hymeniacidon rigida, Lendenfeld, sp. 



Stylotella rigida, Lendenfeld, Catalogue of Sponges in the 

 Australian Museum, p. 186. 



I identify with this species a single specimen (R.N. 362) of 

 digitate form, with thick, irregular branches and small vents 

 chiefly on the sides of the branches. The skeleton is a loose 

 reticulation of fairly stout and slender fibres, branching towards 

 the surface, and with very wide irregular meshes between. The 

 fibres contain a great many spicules densely packed together and 

 invested by abundant spongin. A large number of spicules are 

 irregularly scattered between the fibres. The dermal skeleton is 

 very scanty, consisting of sparsely scattered spicules slightly pro- 

 jecting from the surface. The spicules are straight, slender 

 styli, rather abruptly sharp-pointed and sometimes with slightly 

 developed heads. They vary much in thickness, averaging say 

 about 0T7 by O005 mm. when full-grown. Judging from the 

 fragment sent for identification, I believe that B.M. sp. 73, left 

 undescribed by Mr. Carter, also belongs to this species. 



R.N. 362 (20 f.; "pale terra-cotta red"). 



B.M. sp. 73 (Reg. 86-12-1 3-35). 



Genus Axinella, Schmidt. 

 Sponge typically ramose but may be massive. Skeleton fibre 

 plumose. Megascleres stylote and sometimes oxeote. No 

 microscleres. 



