402 REVISION OF THE MONAXONID SPONGES, ill., 



Ridley and Dendy (34a), in their remarks on Sideroderma, refer 

 to the fact of their having been enabled "through the kindness of 

 Dr. R. V. Lendenfeld, to examine a second species (of the genus) 

 which occurs in his large collection of Australian sponges." Pro- 

 bably this species has generally been thought to be Sideroderma 

 zitelii, but one must now conclude that it has never been 

 described. 



ESPERELLA RIDLEYI. ( Text-fig.l3.) 



Introductory. — The species is represented in the collection by 

 two specimens, one of which is that figured in the Catalogue in 

 illustration of the variety rohusta, while the other is labelled as 

 the type of the variety intermedia. As the two are exactly alike in 

 all but details of shape, it would seem as if the latter were incor- 

 rectly! labelled — for, according to description, the variety inter- 

 media should be distinguished by a much softer and more elastic 

 consistency, due to its fewer spicules and finer fibres; however, a 

 British Museum specimen, labelled as belonging to this same 

 variety, is (at any rate in its spiculation) likewise precisely similar 

 to the variety rohusta. Under the eireumstances, and in view of the 

 fact also that the only stated differences between them are insuffi- 

 cient as a basis for distinction, we may reasonably and safely 

 assume that the two so-called varieties are identical. 



A British Museum specimen labelled with the MS. name "Espe- 

 rella ridleyi var. mollis^' (and, indeed, bearing a certain degree of 

 outward resemblance to the present species, due to its trabecular 

 structure) proves to belong to a species of Echinochalina, with 

 spiculation similar to that of Echinochalina intermedia Whitelegge 

 {vide 18). 



Of the several errors needing correction in the original descrip- 

 tion, there is one that calls for special mention. This is the state- 

 ment that, among the microscleres, diancistra occur, which are 

 rare and confined to the surface. The occurrence of diancistra 

 along with anisochelae — of which we have no instance except in 

 the very doubtful case of Schmidt's Vomerula tihicen — would be 

 of oreat interest as affording conclusive evidence of a relationship 



