REVISION OF FRESHWATER SPONGES OF SPONGILLIDAE 15 



study does not permit reliable conclusions as to the relationship of this 

 species to others of the genus, and it is thought advisable to retain its 

 separate specific status until more material wiU be studied. From all 

 other species of the genus, S. aspinosa differs by the presence of smooth 

 microscleres, and from the S. lacustris group by the much firmer 

 gemmular membrane, as well as by the participation of a smaller 

 group of megascleres in gemmular protection. 



Gee (1928) considered this species to be synonymous with S. 

 inarmata Annandale, comparing the arrangements of megascleres 

 around the gemmules, and the absence of gemmoscleres in both species. 

 However, the existing differences between these two species, particu- 

 larly the grossly different development of the gemmular pneumatic 

 layer, represent a reliable means of then* separation. Unless gem- 

 moscleres will yet be found in one or both of these species, indicating 

 the degree of their relationship, it is advisable to consider them closely 

 related though easily separable different species occurring in distant 

 faunal regions. 



Spongilla inarmata Annandale, 1918 



Spongilla inarmata Annandale, 1918, p. 200.— Gee, 1928, p. 222; 1931e, p. 40; 



1932c, p. 39.— Penney, 1960, p. 20. 

 Spongilla aspinosa Annandale and Kawamura, 1916, p. 6. — (Not Potts, 1880). 



Material. — Fraction of type, and two slides of type obtained by 

 N. Gist Gee. 



Description. — Sponge, according to Annandale (1918), forming 

 thin crusts, without branches; surface rather hispid, due to projection 

 of megasclere fibers through dermal membrane. Skeleton consisting 

 of a close irregular network of spicule fibers. Consistency of live sponge 

 brittle. 



Megascleres of moderate length, relatively slender and fusiform 

 amphioxea, completely smooth; length range 158-290 ju, width range 

 4-12 M. 



Microscleres apparently confined to dermal membrane; they are 

 somewhat crescentic in outline and sharply pointed, covered with 

 minute spines mostly in their central region, their tips usually smooth; 

 length range 50-79 n, width range 2-4 ix. 



Gemmoscleres not yet recorded. 



Gemmules apparently restricted to basal part of sponge, ranging 

 280-750 iJL in diameter; outline subspherical to ovoid; pneumatic 

 layer irregular, but usually very thick and granular; smaller mega- 

 scleres often embedded in this layer, and usually a cage of smaller 

 megascleres built freely around each gemmule; foramen only slightly 

 raised, bearing a peripheral shallow collar, never tubular. 



Distribution. — Apparently restricted to Japan. 



