576 riiocEEDiNGS OF THE NATIONAL MUSEUM. 



* SympJiynota temiinsinia LEA, Tr. Am. Phil. Soc., Ill, 1829, p. 453, pi. xi, fig. 



21; *Obs. 1, 1834, p. i>7, pi. xi, tig. 21. 

 Symphynota tenitiaxinia SHOUT and EATON, Transylvania .11., 1831, p. 80. 



* Margarita (Unio) tcnuissimag LEA, Syn., 1836, p. 38; 1838, p. 25. 



* Unio leniiixxiniux HANLKY, Test. Moll.. 1842, p. 206; * Biv. Shells, 1843, p. 206, 



pi. xx, fig. 42. *CATLO\V and KEEVK, Conch. Noin., 1845, p. 64. "H. and A. 

 ADAMS, Gen. Kec. Moll.. II, 1857, p. 491. * SOWERBY, Conch. Icon., XVI, 1866, 

 pi. XLIV, fig. 240. I!. H. \VRIGHT, Check List, 1888. 



* Margaron (Unio) teniiissimus LEA, Syn., 1852, p. 38; 1870, p. 61. 



Upper Mississippi River drainage, south to the Tennessee River; 

 Buffalo, New York ; southern Michigan; Souris River, Manitoba. 



(Group of Lampailix scutulatus.) 



Shell rhombic elliptical, compressed, rather thin, with a high posterior 

 and a low anterior wing, with two posterior ridges; the valves often 

 exhibiting fine radiating plications on the posterior part ; beaks com- 

 pressed, sometimes showing the nepiouic shell, almost destitute of 

 sculpture, which, when present, consists of faint indications of two 

 rounded loops; epidermis rather dull, sometimes indistinctly rayed; 

 left valve with two pseudocardinals, the anterior a sharp, straight 

 ridge sloping obliquely downward and forward from n point just in 

 front of the beaks, the hinder curiously compressed and showing a 

 tendency to break into denticles; right valve with two sharp, ridge-like, 

 sloping pseudocardinals; laterals slender, compressed, straight or 

 wavy; nacre bluish white to pale violet; dorsal scars few; female shell 

 apparently slightly swollen at the posterior base; animal unknown. 



LAMPSILIS SCUTULATUS Morelet. 



* Unio scutulatus MORELET, Test. Noviss., I, 1849, p. 30. * FISCHER and CROSSE, 



Miss. Sci., Pt. 7, II, 1894, p. 561, pi. LIX, fig. 5; LXYII, fig. 6. 



Yucatan. 



LAMPSILIS PALUDOSUS Morelet. 



* Unio paludosus MORELET, Test. Xoviss., I, 1849, p. 30 * FISCHER and CROSSE, 



Miss. Sci., Pt. 7, II, 1849, p. 559. pi. LIX, fig. 3. 



Yucatan. 



LAMPSILIS PLANIVALVIS Morelet. 



* Unio planiralvis MORELET, Test Noviss., II, 1851, p. 24. * FISCHER and CROSSE, 

 Miss. Sci., Pt. 7, II, 1894. p. 560, pi. LIX, fig. 2.' 



Usumasinta River, Guatemala. 



t LAMPSILIS DELPHINULUS Morelet. 



* Unio delphinulus MORELET, Test. Noviss., I, 1849, p. 31. * HANLEY, Biv. Shells, 



1856, p. 381, pi. xxin, fig. 60. SOWERHY, Conch. Icon.. XVI, 1866, pi. XLIII, 

 fig, 237. *B. H. WRIGHT, Check List, 1888.* I'.ETEL, Conch. Sam., Ill, 

 1890, p. 150. * FISCHER and CROSSE, Miss. Sci., Pt. 7, II, 1894, p. 557, pi. 

 LXIII, figs. 2, la, 2b. 



* Marynron ( I'nio) delphinuliix LEA, Syn. 1870, p. 28. 



Guatemala. 



These three may be mere variations of one thing. 



