UNIO 705, 
UNIO TETRALASMUS Say. 
Shell elongated with dorsal and ventral lines nearly parallel, 
convex to subinflated, rather thin to subsolid, inequilateral, 
beaks somewhat full and elevated, their sculpture consisting 
of six or seven moderate concentric ridges, which are evenly 
and rapidly rounded up behind; posterior ridge widely round- 
ed, ending behind in a point just below the median line ; on the 
dorsal slope there are two radiating furrows, the slope being 
slightly, obliquely truncate behind; anterior end evenly round- 
ed; surface with feeble, concentric sulcations, and traces of 
very fine radial sculpture ; epidermis yellowish-brown or ashy- 
brown, banded with lighter color, rather smooth, often sub- 
shining ; pseudocardinals two in each valve, the upper in the 
right valve small, all subcompressed; laterals long, two in the 
left valve and one in the right ; beak cavities impressed ; dorsal 
scars immediately under the beaks; muscle scars smooth and 
shallow ; nacre white. 
Length of Say’s figure 112, height 49, diam. 35 mm. 
Length 96, height 48, diam. 30 mm. 
Alabama to ‘l’exas; north to Southern Missouri and Indian 
Territory. 
Type locality, Bayou St. John, New Orleans, La. 
Unio tetralasmus Say, Am. Conch., III, 1830, pl. xx111.— Han- 
LEY, Biv. Shells, 1843, p. 198, pl. xxi, fig. 49.—CHENU, 
Bib. Conch., 1st. ser., III, 1845, p. 52, pl. x, figs. 1-3.—Simp- 
SON, Syn., 1900, p. 739.—FRierson, Naut., XVII, 1893, p. 
49, pl. 111, upper fig. 
Margarita (Unio) tetralasmus Lea, Syn., 1836, p. 30; 1838, p. 
21. 
Margaron (Unio) tetralasmus Lea, Syn., 1852, p. 32; 1870, p. 
50. 
Uniomerus tetralasmus OrrMANN, Ann. Car. Mus., VIII, 
112) p., 273. 
Unio excultus Conrap, Monog., XI, 1838, p. 99, pl. Liv, fig. T. 
Unio parallelus Conrap, Pr. Ac. N. Sci. Phila., I, 1841, p. 20. 
Unio symmetricus Lea, Pr. Am. Phil. Soc., IV, 1845, p. 164; 
pre nns Phil Sock 1853) p. 73) plea, fie, 17; Obs., IV, 
To4Sy p. "47, “pl. WV, fig. 11. 
