CALCAREOUS SPOXGES. 793 



used for a genus of Asteroidea, and is therefore permanently 

 unavailable. 



ISTardoma Haeckel [1872]. 



Type species N. nitida Haeckel, {■= Leucosolenia niticla). 



Nardopsis Haeckel [1870]. 



Type species iY. gracilis Haeckel, [= Leucosolenia gracilis). 



ISJ'ardgrus Haeckel [1 872]. 



Type species N. primordialis Haeckel, {^= Leucosolenia pri- 

 inordialls). 



Olynthella Haeckel [1872]. 



Type species O.coriacea Montagu, (:=Leiocosolenia coriacea). 



Olynthium Haeckel [1870]. 



Type species 0. nitidum Haeckel, (= Leucosolenia nitida). 



Olyxthus Haeckel [1870]. 



Type species 0. simplex Haeckel, (= Leucosolenia pri- 

 mordialis). 

 This name, as an actual generic name, is considered by us to be 

 merely a synonym of Leucosolenia, but we may point out that its 

 avithor proposed it for what he considered to be the most primitive 

 adult sponge known, and, although we now believe that he 

 probably erred in considering specimens of this form to be adult, 

 yet the name is still retained for a hypothetical genus of an- 

 cestral Calcarea, and for an early stage in the ontogeny of the 

 individual. Even should adult Oli/nthtis-iorms occur, however, 

 we do not consider that they would be generically separable 

 from Leitcosolenia . 



PoLEJNA von Lendenfeld [1891]. 



Type species P. titer Polejaeft", {=Leucilla uter). 

 One of the genera based by von Lendenfeld on the presence of 

 a sylleibid canal system, a character which we do not consider of 

 generic importance. 



Prosycum Haeckel [1870]. 



Type species P. siinplicissimum Haeckel, (= Leucosolenia 

 primordialis). 



Rhabdodermella Urban [1902], 



Type species R. nuttingi Urban, (=Leucilla nuttingi). 



ScYPHA .S'. F. Gray [1821]. 



Type species 8. coronata Ellis and Solander, (=: Sycon 

 coronatum). 

 The genus Scyplia actually has priority over Risso's Sycon, but 



