(32)< 



246 KEY TO THE AUSTRALIAN GENERA. 



Meshes of the skeleton-net small, usually 

 about 0-3 millim.wide. Fibres solid, simple, 

 not forming trellis-like structures. With- 

 out filaments. Sponges not honeycombed. 51 



Meshes of the skeleton-net usually larger, 

 readily visible with naked eye. Fibres 

 solid or pithed. Simple or fascicular. 

 Sometimes replaced by foreign bodies. The 



forms with small meshes of the skeleton- * 



I 



I net honeycombed. Filaments present or 



I- absent (52) 



r Sponges not cavernose, with smooth or 



I grooved surface 53 



I 

 51 <[ Sponges solid or cavernose. Usually conu- 



{ lated ; the cavernose forms sometimes with 



L smooth surface and a sand-cortex ,(54) 



Sponges usually with digitate branches and 

 smooth surface, without cortex. Con- 

 necting-fibres simple, unbranched Chalinopsilla, p. 104. 



Frondose, caliculate, or branched sponges 

 with smooth or grooved surface, or pro- 

 tected by a cortex. When the surface is 

 smooth the lamella is barely 1 millim. 

 thick Phyllospongia, p. 115. 



Compressed, usually lamellar sponges, with a 

 smooth surface without cortex,with branched 

 connecting-fibres and a very fine skeleton- 

 net Leiosella, p. 120. 



/- Vestibular cavities absent or small ; surface 



I conulated Euspongia, p. 125. 



(54) <( Vestibular cavities wider than the intervening 

 septa. Surface conulated, or protected by 

 l_ a sand-cortex and smooth Hippospongia, p. 135. 



53 < 



(52) 



Without filaments 55 



With filaments (56), p. 247. 



fWith smooth cribriform cortex of sand .... Thorecta, p. 142. 

 Surface usually conulated, sometimes irre- 

 gular, never smooth 57 



