594 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxii. 



tNAPHRONAIAS OREGONENSIS Lea.i 



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



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

 Adams, Gen. Eec. Moll., II, 1857, p. 494. — *Musgrave, Phot. Conch., 1863, pi. 

 II, fig. 5.— *SowERBY, Conch. Icon., XVI, 1868, pi. Lxxrv, fig. 383.— * B. H. 

 Weight, Check List, 1888.— * P jstel, Conch. Sam., Ill, 1890, p. 162. 



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



^Nicaragua. 



fNEPHRONAIAS 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.— *PyETEL, Conch. Sam., Ill, 1890, p. 166. 



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



Nicaragua; Guatemala; Ohagres River, Colombia. 



fNEPHRONAIAS 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.,VIL I860, p. 76, pi. xli, fig. 139.— 



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



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



Goascoran Eiver, Honduras. 



fNEPHRONAIAS 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 Eica. 



fNEPHRONAIAS TEHUANTEPECENSIS Crosse and Fischer. 



* Unio ieliuantepecensis Crosse and Fischer, J. de Couch., XLI, 1893, p. 296. — 



* Fischer and Crosse, Miss. Sci., Pt. 7, II, 1894, p. 618, pi. lxv, figs. 3, 3a, 4. 



Isthmus of Tehuan tepee, 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. 



^I 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 

 Unio rowellii Mr. Lea has in his collection two large N. macneilii, one large rowellii, 

 three smaller ones and several valves, and two goascoranensis, 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 macnielii 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 puzzling. This species 

 occurs with N. rowellii and macnielii. 



