REVISION OF FRESHWATER SPONGES OF SPONGILLIDAE 37 



Material. — Syntype slides of S. sinensis (N. Gist Gee), and 

 specimens from Soochow, China; specimens and slides of S. stanleyi 

 (N. Gist Gee) from China and Northern Alanchuria. 



Description. — Sponge usually forming nodulose crusts on sheUs of 

 living bivalves; surface rather smooth, but hispid due to the projection 

 of vertical spicule fibers through dermal membrane; oscula small and 

 inconspicuous, sometimes surrounded by radial canals; dermal mem- 

 brane closely adhering to symplasm, subdermal cavity very small. 

 Skeleton consisting of a dense but irregular network of spicule fibers, 

 forming polygonal meshes at the base and singular fibers toward the 

 surface of the sponge; spongin moderately abundant. Consistency of 

 live sponge firm and compact. 



Megascleres feebly curved to straight, stout amphioxea with 

 abruptly pointed tips, entirely smooth; length range 200-295 n, 

 width range 12-19 n. 



Microscleres absent. 



Gemmoscleres rather robust, usually slightly curved amphioxea, 

 rarely amphistrongyla, ranging from almost smooth to covered with 

 few to many large and irregular spines; length range 65-125 n, width 

 range 8-13 m; malformations of gemmoscleres quite frequent, irregular 

 spiny spherasters often also present. 



Gemmules somewhat depressed, subspherical, forming pavement 

 layer at base of sponge, firmly adhering to support; diameter of inner 

 gemmular membrane 280-350 m; pneumatic layer more or less well 

 developed, of varying thickness, consisting of large polygonal air 

 spaces and forming a continuous coat over gemmules; gemmoscleres 

 embedded in this layer in great numbers, forming several tangential 

 layers over the gemmules; foramen distinctly tubular, porus tube 

 curved and at least reaching surface of pneumatic layer. 



Distribution. — Apparently restricted to Asia, ranging from 

 mainland China north to Manchuria and the U.S.S.R. 



Color in life. — Light green, gray, or blackish brown (Rezvoj). 



Discussion. — Annandale (1910a, 1916, 1918a) reluctantly placed 

 both his S. sinensis and S. stanleyi into his newly erected subgenus 

 Stratospongilla, stating that both these species form a distinct group 

 in that subgenus and that they differed in many regards from all its 

 other species. Gee (1926-1932) used Annandale's grouping without 

 any further comment, but Rezvoj (1930), while retaining the tax- 

 onomic position of S. stanleyi within the subgenus Stratospongilla, 

 made very useful comments on the insufficiency of the original defini- 

 tion of that subgenus. As wiU be shown below, the species to be re- 

 ferred to that genus as here restricted possess gemmules with an ill- 

 developed or entii-ely absent granular pneumatic layer without 

 discernible air spaces, and instead a cover of a dense chitinoid mem- 



