nuT.ODON. 1253 



Dii'i.oDON GRANULiFivRUS (Dunker). 



Shell subelliptical, small, subcompressed, inequilateral, sub- 

 solid ; beaks low, their sculpture not described ; posterior ridge 

 low and rounded, ending behind in a blunt, rounded point near 

 the base line, surface sculptured with fine, granulous. curved, 

 wavy, subradial ridges : epidermis olivaceous ; pseudocardinals 

 delicate; laterals lamellar and curved; nacre iridescent. 



Length 34, height 22, diam. 12 mm. 



Province of Rio de Janeiro, Brazil. 

 Unio granuliferus Dunkek, Zeits. fiir Mai., V, 1848, p. 182. — 



PfeiFFer, Nov. Conch., II, 1866, p. 150, pi. xxxix, figs. 1-3, 

 Diplodon granuliferus Simpson, Syn., 1900, p. 879. 

 Unio granulifcr P.F,TEr., Conch. Sam., Ill, 1890, p. 154. 



I have never seen this species, which mav be merelv a form 

 of D. granosus. The curved rows of nodules are slightly di- 

 varicate along the posterior ridge. It is more nearly elliptical 

 than any specimens of granosus that I have seen. 



Diplodon effui.gens (Lea). 



Shell subtrapezoidal, rather small, subsolid, subcompressed. 

 inequilateral, with apparently low beaks, their sculpture not 

 obsen'ed ; anterior end narrowed and rounded ; post-dorsal 

 region elevated almost into a wing ; post-dorsal slope subtrun- 

 cate ; posterior ridge low and rounded, ending behind in a 

 rounded point near the base line ; surface sculptured v.'ith fine, 

 concentric ridges and showing vestiges of granulation and 

 radial sculpture ; epidermis greenish-brown, shining ; left valve 

 with one subcompressed. irregular pseudocardinal with some 

 uneven denticles behind it and two small, remote laterals; 

 right valve with two pseudocardinals, the upper much com- 

 pressed, the lower prolonged backward and much split up, 

 with one lateral : nacre lurid whitish, thicker in front. 



Length 50, heig;ht 30, diam. 16 mm. 



Brazil. 

 Unio effulgcns Lea, Pr. Ac. N. Sci. Phila., A'lII, 1856, p. 94; 



Jl. Ac. N. Sci. Phila., Ill, 1857, p. 303, pi. xxviii, fig. 18: 



Obs., VI. 1857, p. 2T^. pi. xxviii, fig. 18. 



