Catalogue of Non-Calcareous Sponges. 259 



sidered. Meanwhile as Yvesia is said to have normally diactinal 

 smooth megascleres (though Topsent mentions two exceptions) 

 we may at any rate keep the present species apart. 



Pseudodathria compressa, Carter sp. 



Halichondria compressa, Carter, A.M.N.H., December, 1886, 

 p. 450. 



This is a very remarkable and easily recognised species, 

 evidently by no means uncommon in the neighbourhood of Port 

 Phillip Heads. The compressed, but thick, flabellate form, with 

 broad, vent-bearing margin, is very characteristic. The rather 

 slender fibres, composed of smooth, straight, slender styli held 

 together by spongin, run chiefly towards the surface, the 

 secondary connecting lines being feebly developed. Mr. Carter 

 speaks of the smooth styli as being curved, but this must be a 

 mistake, for even in his type specimen they are characteristically 

 straight. The short, curved, very richly spinecl styli, abundantly 

 scattered throughout the sponge, and forming a dense dermal 

 crust, are also very characteristic. 



R.N. 371 (18 f.; "orange-red"); 541 (x, 19 f.j "vermilion"); 

 543 (x, 19 f.; " saturn-red ") ; 590 (x, 19 f.; "orange-chrome"); 

 632 (x, 19 f. ; " orpiment-orange below deep chrome"); 1041 

 (xB). 



B.M. sp. 28 ("Halichondria compressa, C. Type;" Reg. 86-12- 

 15-9). 



17a 



