REVISION OF FRESHWATER SPONGES OF SPONGILLIDAE 139 



Gemmoscleres minute birotulates with a stout, smooth and short 

 shaft, and terminally with rotules of more or less circular and recurved 

 margins, the upper only very slightly smaller than the lower; length 

 of shaft about 11 /x, its thickness about 4-5 //, diameter of rotules 

 ranging 12-14 n. 



Gemmules rather abundant, confined to lower parts of sponge, 

 subspherical, ranging in diameter 370-410 n; usually encased in 

 capsule of normal megascleres; pneumatic layer apparently granular, 

 never thicker than the length of gemmoscleres; these embedded in a 

 single layer in this coat; foramen produced into a short conical porus 

 tube. 



Distribution. — Known only from a restricted region in the eastern 

 United States. 



Color in life. — Light gray to drab. 



Discussion. — The examination of the few slides available for this 

 study did not reveal any additional criteria for discussion, and future 

 observations and particularly the collection of new material are highly 

 desirable. 



Trochospongilla paulula (Bowerbank, 1863) 



Plate 12, figures 5, 6 



Spongilla paulula Bowerbank, 1863, p. 453. — Jewell, 1952, p. 448. 



Metania paulata Gray, 1867, p. 551. 



Tubella paulula Carter, 1881a, p. 96.— Potts, 1887, p. 248.— Weltner, 1895, 



p. 114. 

 Trochospongilla paulula Gee, 193 le, p. 45; 1932b, p. 20. — Schroder, 1932a, p. 165. 

 Spongilla paulata de Laubenfels, 1936, p. 37. 



Material. — Slides of type (BM); material and slides from the 

 Amazon K. (Gee no. 54826). 



Description. — Sponge, according to pre\dous descriptions, forming 

 small cushions of aquatic vegetation; surface rather imeven, with 

 conical eminences. Skeleton apparently irregular but stout. Con- 

 sistency rigid. 



Megascleres feebly cmwed, slender, and distinctly fusiform amphi- 

 oxea, as a rule entirely smooth, rarely bearing a varying number of 

 minute spines or granules; length range 230-260 n, width range 

 14-16 M. 



Microscleres absent. 



Gemmoscleres moderately large birotulates with a slender and 

 comparatively long shaft, and terminally w^th rotules of more or less 

 circular and slightly recurved margins, the upper one considerably 

 smaller than the lower; length of shaft 24-29 ix, its thickness about 4-5 

 ju, diameter of lower rotule 22-26 n, of upper 9-14 ju. 



Gemmules spherical, ranging in diameter 390-430 ju; pneumatic 

 layer well developed and distinctly granular; gemmoscleres embedded 



