DIPUODON 1 241 



median line ; dorsal line high behind ; dorsal slope subtruncate ; 

 anterior end narrow, rounded ; base line curved, full behind ; 

 surface with- fine concentric growth lines ; epidermis bronzy- 

 green, subshining ; left valve with two rough pseudocardinals, 

 the anterior small, and two laterals : right valve with two pseu- 

 docardinals, the upper small, with one lateral ; dorsal pits deep ; 

 muscle scars small, shallow ; nacre bluish- white. 



Length 28, heiglit 19, diam. 9 mm. 



South America. ? 

 Unio hrozvnii Lea, Pr. Ac. N. Sci. Phila., VIIL 1856, p. 95 ; 



Obs.. VL 1857, p. 27, pi. XXIX, fig. 22 ; Jl. Ac. N. Sci. Phila., 



ITT, 1858, p. 307, pi. XXIX, fig. 22. 

 Margaron (Unio) hronmii Lea, Syn., 1870, p. 61. 

 Diplodon hroumii Simpson, Syn., 1900, p. 876. 



Dr. I,ea had a single specimen of this shell, which he mark- 

 ed "Mocha?" Tt is, I am sure, a South American species close 

 to suavidicus, as the beaks are strongly and regularly radially 

 sculptured. Tt is more compressed and smoother than suazndi- 

 cus, though having a similar outline. Two small shells, which 

 Dr. IvCa called U. hrozvmi, are the former without doubt. The 

 type of hrounui is probably a young shell. 



Diplodon levi Simpson. 



Shell small, subinflated, solid, inequilateral, subrhomboid, 

 with full but not high beaks, which are badly eroded in the 

 only specimen seen ; posterior ridge full, widely rounded, end- 

 ing behind in a rounded point near the base line ; posterior 

 slope truncated behind and angled above ; surface closely, but 

 feebly concentrically sculptured, showing traces of radial sculp- 

 ture ; epidermis dark brown, subshining ; left valve with two 

 somewhat split-up pseudocardinals, the anterior smaller, and 

 two delicate laterals ; right valve with one stronger dentilate 

 pseudocardinal and a smaller smooth one above it, with one 

 lateral ; anterior scars large and impressed ; nacre bluish-white, 

 thicker in front. 



Length 32. height 21. diam. 15 mm. 



Brazil. 



