546 REVISION OF THE AXINELLID.E, ii., 



ing through it, upwards from the stalk, in the manner of the 

 pahnate leaf, and from these the lesser lines of density, in part, 

 branch ott' (at small angles of divergence) in piiniate fashion 

 (PI. xxxvii., fig.3). 



As a result of maceration, the less dense portions of the lamina 

 largely disappear, and the sponge becomes abundantly perforated 

 by rounded holes arranged seriallj^ along radiating lines. 



The surface is somewhat uneven, owing to inequalities in the 

 thickness of the lamina; it is also slightly granular, but not 

 hispid. The dermal membrane is thin and translucent, but not 

 very delicate; situated beneath it, more especially along the 

 grooves marking the less dense portions of the lamina, are 

 numerous small subdermal spaces. Dermal pores occur on l)otli 

 surfaces, but are relatively few and for the most part are scattered 

 singly and irregularly on the one surface (viz., the inner one, 

 when the sponge is cup-shaped), verj^ numerous, and generally so 

 closely arranged as to produce a net-like appearance of the dermal 

 membrane, on the other. In most places where the pores are 

 numerous, the dermal layer appears as if consisting of two 

 incompletely separated membranes, the outer one of which is 

 provided with many, smaller pores, the inner with fewer and 

 much larger ones. On the surface which has the fewer pores, 

 there are also many circular openings, from 02 to 0'5 mm. or 

 slightly more in diameter, situated only along the su if ace-grooves 

 and principally in the positions where the lamina becomes per- 

 forated when the sponge is macerated; these openings appear to 

 be oscula. 



The consistency of the sponge, when well-preserved in alcohol, 

 is firm and tough, only slightly compressible, and resilient; and 

 the colour is a pale yellowish-brown. Dried specimens are ligiit 

 in weight and rather brittle, and of a pale greyish colour. 



Skeleton. — The skeleton is resolvable into (i.)a system of con- 

 densed, multifibrous axes or "funes," which ramify clendritically 

 in the midplane of the sponge-lamina, progressively decreasing 

 in stoutness as they ascend, — and which form the midribs, as it 

 were, of the denser strips of the lamina above referred to; and 



