SPONGES. 209 



This variety is well known in the Mediterranean and, according to Lendenfeld. 

 occurs also in the North Atlantic and in Australian seas. 



R.N. 1G5 (deep water oft' Galle and onwards up West Coast of Ceylon). 



Spongelia elastica, var. crassa, nov. Plate XIV., fig. 4. 



This variety differs from var. lobosa in the much coarser main fibres, filled with 

 much larger foreign particles (sand grains), and in the more areniferous character of 

 the connecting fihres, which, however, are still occasionally quite free from sand. In 

 external appearance (Plate XIV., fig. 4) the single specimen closely resembles the 

 specimen of var. lobosa described above, but it may readily be distinguished by its 

 much more rigid and coarsely arenaceous character. The very stout main fibres 

 contain sand grains of extremely various size. The network of connecting fibres is 

 very irregularly developed and sometimes is absent over wide areas. The sponge is 

 infested by numerous small cha3topod worms imbedded in the soft tissues. 



R.N. 35 (GulfofManaar). 



Spongelia incrustata, n. sp. 



Sponge compressed, irregularly lobose, proliferous. Surface with small acute 

 conuli irregularly scattered over it at varying intervals, and only about 1 millim. in 

 height ; minutely reticulate over large areas, while over areas quite as large the 

 dermal reticulation is completely obliterated by the sand cortex. Vents rather small 

 and mostly on the margins of the lobes. Texture (in spirit) rather soft, compressible, 

 flaccid, cavernous internally. Colour yellowish-grey throughout. The largest 

 specimen is about 100 millims. in maximum diameter, and the lobes are generally 

 not more than 5 millims. or 6 millims. thick, though variable. 



The skeleton consists in the first place of the dense arenaceous cortex, which is 

 well developed everywhere, except in the thin dermal membrane of the pore-areas 

 which lie between the meshes of the dermal reticulation (where j>resent). This cortex 

 is about - 5 millim. thick. Internally the skeleton also consists chiefly of sand- 

 grains, arranged in irregular tracts rather than in well-defined fibres, but often held 

 together by spongin cement. Between these tracts are wide areas free from sand. 



The canal system is that of a typical Spongelia. The sub-dermal cavities, under- 

 lying the pore-sieves, are large, and the whole canal-system is lacunar in a high 

 degree. The flagellate chambers are sac-shaped and up to about 0'08 millim. in 

 longer diameter, opening by wide mouths into the exhalant canals and provided with 

 numerous prosopyles. The mesoglcea between them is very scantily developed, clear 

 and gelatinous, but with numerous stellate connective-tissue cells. The walls of the 

 larger exhalant canals contain numerous elongated muscle-cells. 



This species appears to be nearly related to Lendenfeld's Spongelia laxa from the 

 South Coast of Australia (66), hut the surface conuli are more or less acute instead of 

 rounded, the skeleton fibres are apparently much less well-defined, and the sand 

 cert ex is apparently much thicker. 



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