144 U.S. NATIONAL MUSEUM BULLETIN 272 



shafts, and at either end with distally deflected circular rotules of 

 entire margins; rotules always of equal size and shape. 



Gemmules subspherical, very small, usually restricted to the base of 

 the sponge and fastened to the substratum by a siu'rounding capsule 

 of a smaller series of megascleres; often arranged in groups of 2-5; 

 pneumatic layer consisting of a solid mass of spongin without any 

 trace of air spaces; gemmoscleres embedded in this layer radially, 

 their inner rotules often overlapping each other; foramen simple, 

 but slightly elevated. 



Sponges forming flat encrustations or conspicuously branching 

 masses on various substrata; surface smooth to strongly hispid. 

 Coloration usually light to dark brown. Consistency hard to stony 

 hard. 



Known only from tropical South America. 



Discussion. — The genus Uruguaya consists of a small number of 

 insufficiently known and apparently very closely related species, all 

 restricted to tropical South America. It displays intimate affinities 

 to the genus Trochospongilla in most regards; the gemmoscleres in 

 both are almost indistinguishable. However, the megascleres of 

 Uruguaya and the structure and consistency of its skeleton are dis- 

 tinctly different so that both genera still can be satisfactorily separated. 

 Some future nomenclatural problems were commented on in the dis- 

 cussion of Trochospongilla (p. 134). 



Members of the genus Uruguaya are poorly represented in the ma- 

 terial available for this study; U. amazonica Weltner and U. pygmaea 

 are altogether absent. If additional material cannot be studied in 

 detail and gemmules of U. corallioides remain unknown, the status of 

 the few species dealt with is difficult to assess. 



Uruguaya corallioides (Bowerbank, 1863) 



Plate 13, figures 1, 2 



Spongilla corallioides Bowerbank, 1863, p. 460. — Jewell, 1952, p. 448. 



Uruguaya corallioides Carter, 1881a, p. 100. — Potts, 1887, p. 268. — Hinde, 1888, p. 



6.— Weltner, 1895, p. 1 14.— Cordero, 1923, p. 134; 1925, p. 113; 1928, p. 



259.— Gee, 193 le, p. 36; 1932c, p. 44.— Penney, 1960, p. 60. 

 Drulia corallioides Gray, 1867, p. 552. 



Material. — Slides of syntype (BM); specimens and slides from 

 Uruguay (N. Gist Gee no. 54396) and the Amazon R. (RMS). 



Description. — Sponge usually forming anastomosing cylindrical 

 branches, arising from a flat base, immature specimens often flat 

 crusts; surface comparatively even but distinctly hispid; oscula of 

 moderate size but very conspicuous, usually situated on slightly raised 

 elevations. Skeleton consisting of thick and regular spicule fibers, 

 forming triangular meshes, firmly united by a considerable amount of 



