484 A MONOGRAPH OP THE AUSTRALIAN SPONGES, 



The connecting fiV)res are differentiated into primary 

 thick long and straight ones, and secundry very 

 short and exceedingly slender ones (Plate 36, 

 fig. 6.) 3. Laxifihris. 



The connecting fibres form a particularly dense net- 

 work of thick fibres, with narrow meshes, in 

 the skin, in the interior they resemble Triplicis 

 (Plate 36, fig. 5) 4. Ditela. 



Connecting fibres regularly branched of uniform 



thickness (Plate 36, fig. 2. ) 5. Regularis. 



•Connecting fibres thick, meshes of network very 



small (Plate 36, fig. 4.) 6. Densalis. 



Main and also connectiiig fibres contain in their 

 axes foreign siliceous spicules but no other 

 foreign bodies (Plate 38, fig. 1 .) 7. Silicifihris. 



These sub-genera have been established by me more for the sake 



of convenience than to express real difierences in the relationship 



of dififerent species. If we were to adopt them as such however, 



we would have to consider their mutual relationship as follows : — 



3 Laxifibris, 4 Ditela. 6 Densalis. 7 Silicifihris. 



\y 



2 Triplicis. 5. Regularis. 



1. Irregularis. 



I. SUB-GENUS IRREGULARIS. 

 Euspongia species, the skeleton of which consists of main and 

 connecting fibres. The latter form a regular and fine network. 

 Never more than three fibres join at one point. If these three 

 are of uniform thickness the angles between them are the same. 



The distance between two adjacent joining points is also fairly 

 uniform, so that the meshes are all of uniform size and similar 

 in shape, were the fibres are of uniform thickness. But we find 

 that the fibres are very irregular in this respect from the very 



