﻿STROPHITUS 3C3 



end slightly narrowed; surface with irregular concentric 

 ridges; epidermis smooth and shining, dark tawny or olive, 

 with wide, ill-defined, dark brown, concentric bands; hinge 

 with an imperfect, compressed tooth in each valve just in front 

 of the beaks, with no laterals; beak cavities rather deep but 

 not compressed ; nacre flesh-white ; muscle scars shallow. 

 Length 80, height 46, diam. ;^^ mm. 

 Length 90, height 50, diam. 38 mm. 

 Tombigbee River, Mississippi. 



Type locality, Tombigbee River, Columbus, Miss. 

 Margaritana spillmanii Lka, Pr. Ac. X. Sci. Phila., II, 1858, 

 p. 138; Jl. Ac. N. Sci. Phila., V, 1862, p. 105, pi. XVII, fig.' 

 252; Obs., Vin, 1862, p. 109, pi. XVII, fig. 252.— Clessin, 

 Conch. Cab. Ano., 1876, p. 264, pi. lxxxii, figs. 5, 6. 

 Unio spillmanii Sowerby, Conch. Icon., X\T, 1868, pi. i.xxxii, 



fig- 435- 

 Mar gar on (Margaritana) spillmanii Lea, Syn., 1870. p. 69. 

 Strophihts spillmanii Simp.son, Syn., 1900, p. 619. 



The greatest diameter is at or just behind the middle of 

 the shell. This species differs from 5'. comiasaugaensis in 

 being rather solider, more glossy, and much darker, and in the 

 peculiar banding of the color. The nacre is cleaner and not 

 tinged with blue. It is longer than S. tombigbeensis and 

 smoother. 



Strophitus TOMBIGBEENSIS (Lea). 



Shell irregularly trapezoidal, much narrowed in front,- the 

 hinge line incurved in front and rounded out behind, inflated, 

 scarcely subsolid, with full, high l:ieaks, whose sculpture has 

 not been observed; posterior end obliquely subtruncate above 

 or somewhat rounded, terminating in a point near the hinder 

 base of the shell at the lower end of the high, rather angular 

 posterior ridge; surface with irregular, often subsulcate 

 growth lines; epidermis generally dark olive-green, sometimes 

 with a few lighter green, rays and these may be interspersed 

 with pale greenish-yellow rays, not shining • hinge with a very 

 rudimentary tooth in front of the beaks in each valve; beak 



