SPONGES. 137 



grooves. Between the exhalant canals there is no separable dermal membrane, and 

 there are no conspicuous sub-dermal cavities. Texture between the canals very 

 compact, hut nol very hard and rather friable. Colour (in spirit) very pale grey. 



The skeleton is a very close and pretty uniform reticulation of single oxea, crossing 

 one another in every direction. The dermal skeleton consists only of scattered oxea 

 placed tangentially. 



Spicules. (1.) Oxea (Plate IX., fig. 7, a) ; rather slender, slightly curved, usually 

 somewhat abruptly or even hastately pointed; about 0-25 millim. by 0-008 millim. to 

 0-01 millim. 



(2.) Sigmata (Plate IX., fig. 7, h) ; slender, C-shaped, with shortly and sharply 

 incurved and sharply pointed ends ; often with a slight indication of enlargement or 

 angulation near the middle ; measuring about 01)28 millim. from bend to bend when 

 full grown. 



(3.) Toxa (Plate IX., fig. 7, c); rather short and moderately stout; sharply 

 angulated in the middle and only slightly recurved at the extremities; length up to 

 about 0'044 millim. 



This is a pretty little sponge, evidently very nearly related to the European 

 Gellius angulatus, from which it differs in the somewhat shorter oxea, the consider- 

 ably larger sigmata, and the much shorter toxa. It is possible also that the arrange- 

 ment of the exhalant canals may be characteristic. It is interesting as indicating 

 that sigmata and toxa are simply slightly different modifications of the same form of 

 microsclere. 



P.N. 140 (deep water offGalle and onwards up West Coast of Ceylon). 



Gelliodes, Ridley. 



Gelliina? with much spongin, more or less completely enveloping or even replacing the 

 megascleres and forming distinct fibres. The microscleres are sigmata. 



Gelliodes carnosa, Dendy Plate VII. , fig. 5. 

 1889, Gelliodes carnosa, Dendy (3). 



There is one fine specimen of this sponge in the collection, easily recognized by its 

 characteristic external form (Plate VII., fig. 5). The megascleres are much slenderer 

 than in the types and appear to be becoming vestigial, as in so many chalinine 

 sponges, being functionally replaced by the strongly developed horny fibre. The 

 sigmata are still numerous, about 0"02 millim. long, but very slender. 



This species forms a conspicuous feature of the Ceylon Sponge-Fauna. 



P.N. 69 (Stat. XXVII. , Cod Bay, Trincomalee, 5 fathoms; also Gulf of Manaar). 



Gelliodes incrustans, n. sp. Plate IX., fig. G. 



Sponge thin, encrusting ; the single specimen growing over both valves of a Pecten 

 (which was evidently alive when collected). Maximum thickness about 7 millims. 



T 



