526 A MONOGRAPH OP THE AUSTRALIAN SPONGES, 



less vertical to tke primaries. Their thickness varies from 0-0033 

 to 0-01 mm. They are, like the primaries not at all numerous, so 

 that the whole network in the interior attains such wide meshes 

 that I would not place this sponge in the genus Euspongia at all, 

 where it not for the very dense network of connecting fibres which 

 forms a thick superficial layer. 



This latter is totally different from the network in the interior. 

 It is formed of an ordinary dense uniform and irregular network, 

 and forms a layer nearly 0-5 mm. thick on the surface. 



The fibres which form this network possess an average thickness 

 of 0017 mm. (0-01-0-015 mm. Selenka I.e.), and the meshes of it 

 are 0-05 mm. wide and rather irregular. 



O. Schmidt (1) established his genus Ditela for a sponge with 

 such a special superficial skeleton, he afterwards (2) however, 

 united Ditela again with Spongia. It belongs doubtlessly to 

 Euspongia (3.) The sub-genus of this name which I have esta- 

 blished above for this species is not identical with O. Schmidt's 

 (1. c. I.), original genus Ditela, as the interior skeleton of the two 

 difier, but I have adopted it for the sake of simplicity, as a name 

 witli which we are familiar, and of which we know that it means 

 a sponge with a special superficial skeleton. 



Nothing is known of the histology of this sponge. 



Geographical Distribution. 



South Coast of Australia, Port Phillip, (F. Mueller, Selenka, 

 Yon Lendenfeld.) 



Bathymetrical Distribution. 

 Shallow water? 



(1) O.Schmidt. Die Spongien des Adriatischen Meeres, 1862. Seite 24. 



(2) 0. Schmidt. Supprement der Spongien des Adriatischen Meeres, 

 enthaltend. Die Histiologie und Systematische Erganzungen, 1864. Seite 27. 



(3) F. E. Schulze. Untersuchungen iiber den Ban unci die Entwickhing 

 der Spongien. Siebente Mittlieilung. Die Familie der Spongidte. Zeitschrift 

 fiir wissenschaftliche Zoologie. Band XXXII., Seite 620. 



