I'LATK XC. 329 



Plantes at Paris, described and figured by mo in tlie 

 ' Proceedings of the Zoological Society of London ' for 

 18C9, and designated Iphitcon panicea, is constrncted 

 on the same principle of confluent rotulate areas of solid 

 siliceous fibres. No fragments of the expansile dermal 

 system of this sponge were to be found on the 

 sjoecimen. 



The structure of the skeleton is not symmetrical like 

 that of the dermis. The fibre is stout and compact, 

 and in the deeply seated portions of the sponge it does 

 not appear to assume any especial direction ; but im- 

 mediately beneath the surface the fibres take a direct 

 course to the inner surface of the dermal membrane, 

 upon which they terminate, dividing and spreading 

 over it, and so forming its beautiful confluent rotulate 

 dermal rete. 



In some parts of the interstitial meml^ranes the 

 tension spicnla are very numerous, while in other parts 

 they are very few in number. 



