3/2 REVISION OF THE MONAXONID SPONGES, 11., 



Description. — The single specimen is a solid massive sponge, of 

 somewhat brick-siiaped form (but with rounded angles and partly 

 uneven surface), measuring 55 mm. in height, and 45 mm. by 30 

 mm. in cross-section; the inequalities of the surface are mostly 

 restricted to the upper aspect of the sponge, and take the form of 

 conical, dome-shaped, or papilliform elevations of small size, the 

 largest (which is of exceptional size) measuring 6 mm. in height, 

 and 5 mm. across at its base. There is a well-developed, non- 

 separable, dermal membrane, with smooth, almost glabrous, sur- 

 face. Oscula of minute size, certainly less than 0-5 mm. in width, 

 are probably present, and, judging by the direction of the main 

 excurrent canals, occur on the upper surface, generally (though 

 apparently not exclusively) at the summits of the elevations; as, 

 however, the canals are of very small size (being rarely as much as 

 1 mm. in diameter), and are not traceable, owing to their partial 

 collapse, all the way to the surface, the existence of undoubted 

 oscula could not be demonstrated. 



The colour in alcohol is yellowish within, and dull white on the 

 surface. In consistency, the sponge is moderately firm, yet com- 

 pressible, and, by reason of its fibrous skeleton, is resilient and 

 fairly tough. 



The main skeleton is a reticulation of spiculo-spongin fibres be- 

 tween which there lie scattered, w^ithout recognisable order and in 

 varying abundance, usually not numerous megascleres and 

 raphides, the latter occurring both singly and in bundles; entering 

 into its composition also, but not contributing to form the reticula- 

 tion, are occasional (yet constantly occurring) continuous strands 

 of loosely associated, parallel spicules uncemented by spongin. 

 The spicules of the sponginous fibres are styli and tylota, the latter 

 relatively very scarce except in the ectosomal region ; in the aspon- 

 ginous fibres, on the other hand, the tylota may predominate over 

 the styli, and also a few raphides make their appearance. The 

 scattered megascleres are chiefly tylota. The skeleton-reticulation 

 consists chiefly of multispicular main fibres (with compact spicule- 

 core, on tlie average less than ten spicules broad) running irregul- 

 arly, usually not much more than a spicule's length apart, and 



