S36 



REVISION OF THE MONAXONID SPONGES, 11. 



meagre, and, moreover, is found to be not quite accurate. The 

 species consequently needs redescription. Unfortunately, the 

 specimen is only a very small piece of the original, and affords 

 no information concerning the external form, or the character 

 and arrangement of the oscula. In regard to these features, 

 therefore, I have in the following description, in order to 

 make it as far as possible self-complete, rewritten what is 

 stated in the original description. 



Fig. 4. — Petrosia hebes. a, Strongyla. 6, Oxea. 



Description. — "Irregular, massive sponges, horizontally ex- 

 tended, 80mm. broad and 30mm. high ; with digitate processes 

 oa the upper surface, which attain a length of 40mm. and a 

 thickness of 15mm. ; they are irregularly curved, knotty, and 

 often flattened. The surface is smooth. Oscula inconspicuous 

 and scattered, circular, 1 to 3mm. in diameter." 



The single piece, which is preserved in alcohol, shows a 

 thin, delicate, non-separable dermal membrane. The consis- 

 tency is firm and fairly hard, but brittle and somewhat pul- 

 verable. The texture is finely porous; the colour, light yellow- 

 ish-grey. 



