REVISION OF FRESHWATER SPONGES OF SPONGILLIDAE 125 



described and figured by Penney (1933) and used by Jewell (1952) for 

 the erection of Parameyenia are the two types of typical gemmo- 

 scleres in any range of A. ryderi, and the megascleres obviously also 

 belong to that species. Consequently, the genus Parameyenia must 

 now be considered a nomen nudum and S. discoides relegated to a 

 synonym of A. ryderi. 



While the identity of S. novae-terrae and S. discoides can now be 

 considered as resolved, some additional taxonomic problems have yet 

 to be cleared up. In the material available for this study, specimens 

 are represented which certainly belong to this genus, but which seem 

 specificially or at least subspecificially distinct from C. everetti. These 

 specimens are here disregarded, since they will be dealt with in a 

 forthcoming paper by F. Harrison (pers. comm,). 



Corvomeyenia everetti (Mills, 1884) 



Meyenia everetti Mills, 1884, p. 146.— Potts, lSS4b, p. 216; 1887, p. 230.— MacKay, 



1889, p. 92.— Kellicott, 1891, p. 103.— Kirsch, 1909, p. 37.— Jewell, 1952, p. 



453. 

 Ephydatia everetti Weltner, 1895, p. 122; 1913, p. 480.— Smith, 1921, p. 17.— 



Jewell, 1939, p. 163. 

 Corvomeyenia everetti Weltner, 1913, p. 480.— Gee, 1931e, p. 37; 1932c, p. 27.— 



JeweU, 1952, p. 453.— Penney, 1960, p. 35. 



Materials. — Specimens and sHdes from various localities in the 

 eastern U.S.A. (Jewell, N. Gist Gee). 



Description. — Sponge always extremely delicate, forming very 

 small encrustations on aquatic plants; surface with noticeable projec- 

 tions, but distinctly hispid; oscula extremely inconspicuous, dermal 

 membrane well developed and closely adhering to symplasm. Skeleton 

 consisting of ill-defined and irregular spicule fibers without organized 

 arrangement, joined together by negligible amounts of spongin. Con- 

 sistency very soft and fragile. 



Megascleres slender, feebly cmwed, distinctly fusiform amphioxea, 

 entirely smooth; length range 195-285 /x> width range 609 /x. 



Microscleres microbirotulates with a slender, smooth, feebly curved 

 or straight shaft, and terminally with a circular arrangement of 5-8 

 distinctly recurved spines, representing an umbonate rotule; length 

 range 16-19 n, average thickness of shaft 2 n, diameter of rotules 

 3-5 n. 



Gemmoscleres birotidates of two not very distinct length groups, 

 but more or less of one class; consisting of a straight, slender, and 

 smooth shaft, and terminally of equal umbonate rotules, represented 

 by a circular arrangement of 5-7 distinctly recurved stout spines; 

 length range of longer series 60-72 n, of smaller 42-57 ju; thickness of 

 shaft 3-5 n, diameter of rotules 16-19 /i. 



