874 PROCEEDINGS OF THE NATIONAL MUSEUM. 



tDIPLODON AMPULLACEUS Lea. 



* Unio ampullaceug LEA, Pr. Ac. N. Sci. Phila., X, 1866, p. 34 ; * Jl. Ac. N. Sci. Phila., 



VI, 1868, p. 269, pi. xxxv, tij,'.83; * Obs., XII, 1869, p. 29, pl.xxxv, fig. 83. 



* Margaron ( i'nlo) ampullae-ens LEA, Syn., 1870, p. 53. 



South America. 



tDIPLODON APPRIMUS Lea. 



* Unio apprimus LEA, Pr. Ac. N. Sci. Phila., X, 1866, p. 34; * Jl. Ac. N T . Sci. Phila., 



VI, 1868, p. 263, pi. xxxai, fig. 78; Obs., XII, 1869, p. 23, pi. xxxm, fig. 78. 



* Margaron ( Unio) apprimus LEA, Syn., 1870, p. 46. 



South America. 



tDIPLODON WYMANII Lea. 1 



'Unio wymanii LEA, Pr. Ac. N. Sci. Phila., IV, 1860, p. 90; *J1. Ac. N. Sci. Phila., 

 VI, 1863, p. 381, pi. XLII, fig. 289; *Obs., X, 1863, p. 17, pi. XLII, fig. 289. 

 *SOWERBY, Conch. Icon., XVI, 1868, pi. LXXXIV, tig. 449. "VON MARTENS, 

 Mai. BL, XV, 1868, p. 193.* P^TEL, Conch. Sam., Ill, 1890, p. 172. 



" Margaron (Unio) wymanii, LKA, Syn., 1870, p. 35. 



Uruguay River, South America. 



DIPLODON EXPANSUS Kuster.- 



* Unio expansus KUSTEK, Conch. Cab. Unio, 1856, p. 149, pi. XLIII, fig. 5. * P^ETEL, 



Conch. Sam., Ill, 1890, p. 152. 



Brazil?. 



tDIPLODON PECULIARIS Lea. 



* Unio peculiaris LEA, Pr. Ac. N. Sci. Phila., X, 1866, p. 33; * Jl. Acad. N. Sci. Phila., 



VI, 1868, p. 265, pi. xxxiv, tig. 80; Obs., XII, 1869, p. 25, pi. xxxiv, fig. 80. 



* Margaron ( Unio) peculiaris LEA, Syn., 1870, p. 47. 



* \Unio paraguayenHis LEA, Pr. Ac. N. Sci. Phila., X, 1866, p. 34; *J1. Ac. N. Sci. 



Phila., VI, 1868, p. 271, pi. xxxv, fig. 85; Obs., XII, 1869, p. 31, pi. xxxv, fig. 

 85. * VON MARTENS, S. B. Nat. Fr., 1895, p. 34. 



* Margaron ( Unio) paraguayensis LEA, Syn., 1870, p. 45. 



*1Unio nitidulits KUSTER, Conch. Cab. Unio., 1848, p. 226, pi. LXXVI, tig. 6. 

 - P.ETEL, Conch. Sam., Ill, 1890, p. 161. 



Paraguay. 



tDIPLODON FIRMUS Lea. 2 



'Uniofirmus LEA, Pr. Ac. N. Sci. Phila., X, 1866, p. 33; ML Ac. N. Sci. Phila., VI, 

 1868, p. 267, pi. xxxiv, fig. 82; *Obs., XII, 1869, p. 27, pi. xxxiv, fig. 82. 



* Margaron ( Unio) firmus LEA, Syn., 1870, p. 45. 



DIPLODON FIRMUS var. BCETTGERI von Ihering. 



* Unio firmns LEA var. bacttgeri VON IHERING, Arch, fur Nat., 1893, p. 105, pi. IV, 



fig. 2.* NEHRING, Jl. tie Couch., 1894, p. 83. 



Brazil. 



1 Extremely close to apprimus, and probably only a young shell of that species. 



4 1 know nothing of this. It looks more like an Australian than a South American 

 form, and is quite likely a />. australis. Kuster credits it to Charpentier manu- 

 script. 



:! A little longer and more solid than peculiaris, but I doubt whether it is distinct. 

 The types of these two and paraguayensis are badly worn. 



