EUSPONGIA. — HIPPOSPONQIA. 135 



0-1 millim. The foreign spicule-fragments occasionally attain a length of 0-14 

 millim. The meshes of the couuecting-fibre-net are of the same size in the 

 vicinity of the main fibres as in intermediate parts of the sponge ; they are 

 occasionally very regnlar, and measnre 0-23 millim. in width. The greater 

 number, 70 per cent, of the connecting-fibres, are uniformly 0-04 millim. 

 thick. There are places in the sponge where all the fibres are 0-04 millim. 

 thict, whilst in others the thinner ones, which measure only 0-014 millim. in 

 thickness, prevail ; in these parts the network is more irregular. 



Geographical Distribution.— South coast of Australia : St. Vincent Gulf, 

 S. A, (Haacl-e). East coast of Australia : Port Jackson, N. S. "W. (Lendenfeld). 

 Fiji (Austr^alian Museim) ; Chatham Islands {Parker). 



Genus HIPPOSPONGIA. 



Spongidae traversed by extensive vestibular lacimse, with a 

 skeleton the connecting-fibres of which form a network with 

 meshes 0-1-0-4 milHm. wide. The species with a wide-meshed 

 skeleton-net are soft and elastic. 



Hippospongia canaliculata, Lendenfeld. 



Eusjpongia canaliculata, E. v. Lendenfeld, " A Monograph of the Australian 

 Sponges. — Part VI. The Genus Euspongia" Proceedings of the Linnean 

 Society of New South Wales, vol. x. p. 502 (1885). 



Irregular, massive, spherical sponges, attached by a small, slightly protruding 

 portion of the broad base, and bearing on the upper side numerous short hollow 

 digitate processes. 



The skeletons particularly, but to a certain extent also dry specimens, show 

 deep and irregular, more or less longitudinally disposed grooves in the surface, 

 which occasionally reach down to the internal cavities of the hollow digitate 

 processes. The development of these grooves and digitate processes is different 

 in the different varieties. 



The skeleton is very elastic, but at the same time harder than that of 

 Euspongia officinalis. 



The surface is destitute of conuli and appears very smooth. With a magni- 

 fying-glass a very regular and uniform network can be discerned in it. There 

 is no difference in the structure of the external surface and that of the ex- 

 tensive vestibular spaces in the interior. The network is similar to the one 

 described above of Euspongia irregularis, being produced by lines raised over 



