SPONGES. 133 



is sub-glabrous, but uneven and very minutely reticulate. The colour below (in spirit) 

 is very pale grey, but on the upper parts of the lobes the grey is mottled with brown. 

 The texture is compact and fleshy ; compressible. 



The two specimens are of about equal size ; the one selected for measurement is 

 about 42 millims. in length, 17 millims. in breadth, and 18 millims. in height. The 

 cortex is about - 164 millim. thick. 



The spicules agree closely in form with those of the thin, encrusting variety. The 

 spherasters are, however, rather smaller. They have, in both varieties, a strongly 

 marked tendency for their rays to be reduced to low warts or even, perhaps, to dis- 

 appear, so that in some cases the large centrum is left almost smooth, as in Keller's 

 C. globulifera, which is, however, specifically distinct. 



A lobate variety of C. australiensis occurs also in Australia. 



R.N. 286, 286a (deep water off Galle and onwards to Colombo. Hauls off Kaltura 

 and off Mount Lavinia, 20 to 30 fathoms, February 19, 1902). 



Chondrosia, Nardo. 

 ChondrosiidaB in which all the spicules have completely disappeared. 



Chondrosia reniformis, Nardo. 



This well-known Mediterranean species is represented in the collection by two 

 specimens, both attached to the same fragment of a horny sponge. Each is roughly 

 hemispherical in form, with wide base spreading out into a broad, thin "stolon" on 

 one side. The surface is covered with low, irregular tubercles, which may be due in 

 part to contraction. The vents are small and difficult to make out, sometimes, at any 

 rate, on low mammiform projections. The structure of the dense fibrous cortex, with 

 its pigment cells, and that of the choanosome, agree very closely, so far as can be 

 made out in the material at my disposal, with Schulze's classical description (40). 

 The pigment cells, however, appear to be mostly in the inner part of the cortex, 

 instead of in the outer part as figured by Schtjlze ; but this is not an important 

 difference. Each specimen is about 13 millims. in diameter, and the colour (in spirit) 

 is mottled grey and brown on the surface, and pale greyish-yellow internally. 



R.N. 226 (two specimens ; deep water off Galle and onwards up West Coast of 

 Ceylon). 



Sub-order: SI GMATOMONAXONELLID A. 



Monaxonellida in which the typical microscleres are sigmata, or forms derived 

 therefrom, normal astrose microscleres being absent. 



The sponges which comprise this large sub-order may be regarded as descended 

 from the tetractinellid sub-order Sigmatophora (family Tetillidoe) by reduction of the 

 megascleres, in the same way that the Astromonaxonellida may be regarded as being 

 derived from the tetractinellid Astrophora. 



