﻿I.AMPSILIS 



35 



with a broad, shallow, radial depression in front of the poste- 

 rior ridge, or having the disk at least flattened. Female shell 

 usually ovate, sometimes inflated, smaller than that of the 

 male, with a feebly developed marsupial swelling on the base 

 near the posterior end. This is rougher than the rest of the 

 shell and shows the strong folds within. 



Length (male) 51, height ^z,, diam. 21 mm. 



Length (male) 42, height 2^, diam. 17 mm. 



Length (female) 37, height 25, diam. 20 mm. 



Length (female) 34, height 25, diam. 14 mm. 



Tennessee River drainage. 



Type locality. Elk and Flint Rivers. Tenn. 

 Uuio ccrlatus Conrad. Am. Jl. Sci.. XXV, 1834. p. 338. pi. i, 



fig. I ; New F. W. Shells. 1834. p. 2(). pi. 11 1, fig. 4: p. 68.— 



Chknu. Bib. Conch., ist ser. III. 1845, P- 16. pi. ni, fig. 3. — 



Rkeve, Conch. Icon.. XVI, 1864, pi. 11, fig. 7. 

 Margarita fUiiio) ccrlatus Lea, Syn. 1836, p. 12; 1838, p. 14. 

 Margaron (Unio) ccrlatus Lea. Syn. 1852, p. 20; 1870, p 20. 

 Micromya ccclata Simpson, Syn., 1900. p. 52=;. 



ViHiile the shells of this species dififer somewhat from those 

 of M. fabalis, it is more in degree than in diversified characters. 

 The latter rarely exhibits even traces of corrugated sculp- 

 ture, yet it is sometimes seen, especially on the marsupial 

 swelling. M. ccrlata is generally much higher than M. fabalis, 

 but there are specimens of the females of both species before 

 me that are much alike in outline. Both species are colored 

 much alike and the marsupial swelling, the heavv shell, wide 

 hinge plate, club-shaped laterals and small, deep muscle scars 

 are much alike. 



The citation of this species from Michigan by Sager and 

 Miles is certainly erroneous. 



Genus LAMPSILIS Rafinesque, 1820. 



Lampsilis Rafinesque, Ann. Gen. Sci. Phys. Brux., 1820, p. 



2g8. — Ortmann, Ann. Car. Mus., VIII, 1912, p. 345. 



Shell oval to elliptical, smooth or slightlv concentrically 

 sculptured, usuall}- without a posterior ridge; epidermis gen- 



