594 PROCEEDINGS OF THE NATIONAL MUSEUM. VOL.XXII. 



tNAPHRONAIAS OREGONENSIS Lea. 1 



* Unio oregonensis'LKA, Pr. Am. Phil. Soc:, V, 1852, p. 252; *Tr. Am. Phil. Soc., X, 



1852, p. 275, pi. xxn, fig. 33 ; * Obs., V, 1852, p. 31, pi. xxii, fig. 33.* H. and A. 

 ADAMS, Gen. Rec. Moll., II, 1857, p. 494. * MUSGRAVE, Phot. Conch., 1863, pi. 

 n, fig. 5. *SOWERBY, Conch. Icon., XVI, 1868, pi. LXXIV, fig. 383. * B. H. 

 WRIGHT, Check List, 1888. * PJSTKL, Conch. Sam., Ill, 1890, p. 162. 



* Margaron ( Unio) oregonensis, LEA, Syn., 1852, p. 29 ; 1870, p. 45. 



!N icaragua. 



tNEPHRONAIAS ROWELLII Lea. 



* Unio rowellii LEA, Pr. Ac. N. Sci. Phila., Ill, 1859, p. 153; * Jl. Ac. N. Sci. Phila., 



IV, 1860, p. 256, pi. XL, fig. 136 ; * Obs., VII, p. 74, pi. XL, fig. 136.* SOWERBY, 

 Conch. Icon., XVI, 1868, pi. LXXXVIII, fig. 471.* B. H. WRIGHT, Check List, 

 1888.* P.ETEL, Conch. Sam., Ill, 1890, p. 166. 



* Margaron ( Unio) rowellii LEA, Syn., 1870, p. 35. 



Nicaragua; Guatemala; Chagres River, Colombia. 



tNEPHRONAIAS GOASCORANENSIS Lea. 



* Unio goascoranensis LEA, Pr. Ac. N. Sci. Phila., II, 1858, p. 118; * Jl. Ac.'N. Sci. 



Phila., IV, 1860, p. 258, pi. XLI, fig. 139 ; * Obs., VII, 1860, p. 76, pi. XLI, fig. 139. 



* B. H. WRIGHT, Check List, 1888. 



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



Goascorau Kiver, Honduras. 



t NEPHRONAIAS DYSONII Lea. 



* Unio dysonii LEA, Pr. Ac. N. Sci. Phila., XI, 1859, p. 152 ; * Jl. Ac. N. Sci. Phila., 



IV, 1860, p. 252, pi. xxxix, fig. 132; * Obs., VII, 1860, p. 70, pi. xxxix, fig. 132. 



* B. H. WRIGHT, Check List, 1888. 



* Margaron (Unio) dysonii LEA, Syn., 1870, p. 35. 



Honduras; Costa Rica. 



tNEPHRONAIAS TEHUANTEPECENSIS Crosse and Fischer. 



* Unio ielmantepecensis CROSSE and FISCHER, J. do Couch., XLI, 1893, p. 296. 



* FISCHER and CROSSE, Miss. Sci., Pt. 7, II, 1894, p. 618, pi. LXV, figs. 3, 3a, 4. 



Isthmus of Tehuantepec, Oaxaca, Mexico; Honduras. 

 (Group of Nephronaias reticulatus.) 



Shell evenly elliptical, slightly biangulate behind, solid and inflated ; 

 surface covered with fine, concentric ridges and having delicate, radiat- 

 ing furrows which cut the sulcations and form them into loops. 



1 1 formerly believed that this species, with the one preceding and following it, 

 ran together. More recent study, with a large amount of additional material, 

 inclines me to think that perhaps they may be valid species. Under the name of 

 I'nio rowellii Mr. Lea has in his collection two large N. macneilii, one large roicellii, 

 three smaller ones and several valves, and two goascor anemia, a species which is 

 very close to the rest, but probably as good as most of the Mexican forms. I find 

 specimens which I can scarcely refer with certainty to macnielil or oregonensis, but 

 which seem to have to some extent the characters of both. This, with a number of 

 the Mexican and Central American forms, is exceedingly pu/xling. This species 

 occurs with N. rowellii and macnielii. 



