1248 DIPI.ODON 



Unio (ctJiiops Lka, var. piracicabana von Thinking, Arch, fiir 



Nat., 1893, p. 102. 

 Diplodon cethiops var. piricicabana Simpson, Syn., 1900, p. 



S77. 



Diplodon divaricatus (Lea). 



"Shell elliptical, transverse, somewhat compressed, very in- 

 equilateral ; substance of the shell thin ; beaks covered with 

 beautiful folds diverging from their apex ; ligament rather 

 short and slender ; epidermis greenish, smooth ; cardinal teeth 

 small, compressed, double in the right valve and single in the 

 left ; lateral teeth long, rather thin and nearly straight ; ante- 

 rior cicatrices slightly confluent ; posterior cicatrices confluent ; 

 dorsal cicatrices situated in the centre of the cavity of the 

 beaks ; cavity of the beaks shallow and subangular ; nacre 

 white and iridescent. 



Length 1.4, height .9, diam. .5 inches." (Lea). 



South America. 

 Unio divaricatus Lea, 1 r. Am. Phil. Soc, V, 1834, p. 64, pi. 



jx, fig. 24; Obs., L 1834, p. 176, pi. IX, fig. 24. — Hanley, 



Biv. Shells, 1843, P- ^97- P-- xxm, fig- 36. 

 Margarita (Unio) divaricatus IvTXa, Syn., 1836, p. 29; 1838, p. 



21. 

 Margaron (Unio) divaricatus Lea, Syn., 1852, p. 31 ; 1870, p. 



49- 

 Diplodon divaricatus Simpson, Syn., 1900, p. 878. 



Credited by Lea to Egypt, but no doubt a South American 

 species, as it has radial beak sculpture and appears to belong 

 to this group. 



Diplodon perpi.exus n. s. 



Shell long elliptical or subrhomboid, convex, inequilateral, 

 rather solid, usually subtruncate in front ; posterior slope 

 curved or feebly truncate ; posterior ridge low, rounded, end- 

 ing behind in a rounded point a little below the median line ; 

 beaks scarcely inflated or elevated above the dorsal line, with 

 numerous, strong, uneven, radial bars, the central pair coalesc- 

 ing below : surface with numerous, fine, concentric ridges ; epi- 



