662 REVISIOX OF THE AXINELLID^, iii., 



in colour and somewhat hai'sh to the feel, and remains slightly 

 crushed when much compressed by squeezing. 



Shpleton. — In each constituent lamella tlie skeleton consists of 

 numerous, closely arranged, pauciserial main lines of spicules 

 running in the plane of the lamella upwards and outwards to its 

 periphery, and of numei^ous short secondary lines and single 

 spicules connecting the^e in irregular manner, the whole forming 

 an exceedingly dense and intricate reticulation (PL xl., figs. 1, 2). 

 The spicules of the fibres are arranged in a somewhat loose, 

 irregular, and slightly plumose fashion, and are held together 

 and more or less ensheathed by a rather small amount of spongin, 

 which, being of a pale colour, is inconspicuous unless stained; 

 the interfibral spicules, for the most part, are invested with 

 spongin only at their extremities or lie quite free. The skeleton- 

 reticulation is so dense, especially towards the central region of 

 the lamella {i.e., towards the mid-plane of the sponge), that, in 

 sections of the oi'dinary thickness for studying the skeleton- 

 pattern, it appears as if consisting of a confused mass of spicules 

 without definite arrangement. In the interlamellar regions of 

 the sponge, except where junctions between the lamellae occui', 

 the skeleton consists solely of spined microxea scattered in great 

 profusion, and of very scarce scattered megascleres. The inter- 

 lamellar regions are traversed by numerous main canals, the 

 largest of which are about 1 mm. in diameter. 



The previous description of the skeleton, given by Dendy, 

 which differs rather considerably from the above, was evidently 

 based upon an insufficiently thin (and "undesarcodised") section 

 cut across the thickness of the sponge obliquely to the mid-plane 

 (and, therefore, intersecting several lamellje). The description is 

 as follows: "The skeleton is very confused and ii'regular, without 

 any definite fibre, composed of densely intermingled oxeote 

 spicules, especially aggregated in wide tracts which trend towards 

 the surface and end in the conuli. The presence of these ill- 

 defined ti'acts of .spicules, with intervening spaces almost free 

 from megascleres, gives a somewhat columnar chai'acter to the 

 vertical sections. Internally, all the tx'acts unite into one dense, 



