248 KEY TO THE AUSTRALIAN GENERA. 



r Supporting- skeleton composed of large sand- 



I grains. Large sigmata always present .. Plioriospongia,p.l92. 

 63 <^ 



Supporting-skeleton horny. Microsclera 



small sigmata or rods Sigmatella, p. 195. 



r Supporting-skeleton horny. Fibres invested 

 by a sheath composed of small spindle- 

 shaped siliceous bodies Haastia, p. 204. 



(64) <( Supporting-skeleton composed chiefly of large 



sand-grains ; without a fibre-sheath Psammopemma, 



Supporting-skeleton horny; without a fibre- [P- ^^^' 



sheath Spongelia, p. 205. 



r Fibres without echinating spicules 65 



I Fibres with echinating spicules (66) 



65 



^ "With rind. Microsclera isochelae, trichites, 



and usually sigmata Sideroderma, p. 210. 



"Without rind. Megasclera palmate aniso- 

 L chelae, and sometimes sigmata Esperella, p. 211. 



(Echinating spicules spined styli 67 

 Echinating spicules spined strongyla (68), p. 249. 

 Echinating spicules smooth stjdi (69), p. 249. 



f Megasclera in the fibres spined styli Myxilla, p. 214. 



J Megasclera in the fibres large smooth styli . . Clathriodendron, 



I Megasclera in the fibres small and slender LP* -'-'^^• 



L smooth oxea and sometimes styH 70 



''The supporting-skeleton is composed of horny 

 fibres with axial bundles of spicules, from 

 which the not numerous echinating spicules 

 protrude Clathria, p. 221. 



The supporting-skeleton consists of dense 

 ^.^ bundles of spicules with veiy little spongin, 

 from which the fairly numerous echinating 

 spicules protrude Clathrissa, p. 217. 



The supporting-skeleton consists of spicule- 

 bundles. The echinating spicules are so 

 numerous as completely to hide the fibre to 

 ^. which they are attached Echinonema, p. 219. 



