308 REVISION OP THE MONAXONID SPONGES, i., 



cially those involved in the statement that "subdermal cavi- 

 ties are found in the shape of tangentially extended canals 0-2 

 mm. below the surface, which are, on an average, 01 7mm. 

 wide, and connected with inhalant pores on the outer surface 

 by straight or curved canals, 0024mm. in diameter." The 

 presence of these subdermal spaces, canals, and pores, I have 

 been unable to demonstrate ; but the sponge is so loaded with 

 foreign matter, including abundant and often large sand- 

 grains, that thin sections are possible only after prolonged 

 desilicidation, and it is then very difficult to distinguish be- 

 tween spaces proper to the sponge and those due to particles 

 removed. I have found another (apparent) example of the 

 species, however, which, throughout considerable portions of 

 the interior, is comparatively free from inclusions ; and this 

 differs from the type-specimen in other respects also. It has 

 been described by Whitelegge(56) under the name Reniera colJec- 

 tn,r, of which species it is labelled as the type ; for the reasons 

 given below, 1 am of opinion that it is correctly labelled so, 

 and accordingly hold Ckondrosia collect rix and Reniera coUec- 

 trix to be synonymous. 



Descripfion,. — The sponge is provided with a thin cortex, 

 not easily separable nor distinctly marked off from the under- 

 lying tissue, which is of a pale greyish or dirty- white colour, 

 and generally about 0-2 or 0-3mm. in thickness. In the type- 

 specimen of Reniera collectrid, the colour of the choanosome, 

 where not disguised by foreign inclusions, is brownish-yellow, 

 and this is in accordance with Lendenf eld's statement regard- 

 ing the internal colour of Chondrosia collecfrir: but in the 

 type-specimen of the latter species, the colour is greyish, and 

 scarcely different from that of the cortex. The two specimens 

 also differ very considerably in consistency. The former, 

 where most free from inclusions, is dense, fleshy, firm, and 

 fairly tough ; but the latter, owing to the abundance and 

 mainly arenaceous nature of the foreign elements, is, for the 

 most part, hard and gritty. The "slightly conulated" appear- 

 ance of portions of the surface, referred to by Lendenfeld, is 



