KEY TO THE AUSTEALIAN GENEBA. 



243 



(28)^ 



29 



f Skeleton uniform 29 



Skeleton forming an axial stem composed of 



a dense network of spicule-bundles, from 



which distant fibres extend in a plumose 



manner to the surface. Subdei'mal cavities 



1^ very large. (AxinellidcTe.) (30), p. 249. 



Supporting-skeleton composed of cemented, 



usually oxeote spicules, without micro- 



sclera. Skeletal fibre never echinated. 



(Homorrhaphidae.) 31 



Supporting-skeleton composed of solid or 



pithed horny fibre or scattered foreign 



bodies, without proper spicules of any kind. 



Ground-substance granular. Chambers 



spherical and small. (SpongidaD.) (32), p. 246. 



Supporting-skeleton composed of cemented 

 spicules, usually with sigmate or other 

 microsclera. Without chelae. Skeletal 

 fibres never echinated. The supporting- 

 skeleton of the forms without microsclera 

 consists usually of strongylote or stylote 

 spicules. (Heterorrhaphidse.) (33), p. 247. 



Supporting-skeleton composed of solid horny 

 <( fibre, usually very rich in foreign material ; 

 or of scattered foreign bodies. Without 

 proper spicules in the fibres. Microsclera, 

 when present, sigmata or rods. Chambers 

 larger, oval. Ground- substance hyaline 

 and transparent. (Spongelidse.) (34), p. 247 



Supporting-skeleton composed of cemented 

 spicules. Microsclera chelae, to which 

 others may be added. When chelae absent, 

 skeletal fibres echinated by proper spicules. 



(Desmacidonidae.) (35), p. 248. 



Supporting-skeleton composed of horny fibre, 

 with or without foreign bodies. Without 

 proper spicules in their axis. The super- 

 ficial fibres may be echinated by proper 

 spicules. Microsclera absent. Chambers 

 small and spherical. Sponges hard, reti- 



l^ culate. (Aulenidae.) (36), p. 249. 



k2 



