JVew species of Fresh Water Shells. 339 



pressed ; anterior muscular impression profound : posterior one slight- 

 ly impressed ; nacre white. 



Observations. The regular ovate form of this shell will distin- 

 guish it from most other species. The young shell, however is broad- 

 er behind, approaching to an oval figure, and is prettily ornamented 

 with green rays on an olive yellow ground. 



UnIO LIENOSUS. PI. 1. fig. 4. 



Shell narrow-elliptical, ventricose ; beaks approximate, litde ele- 

 vated and corrugated; posterior basal margin abruptly rounded; pos- 

 terior end sub-angulated ; cardinal teeth rather compressed and ob- 

 lique, and double in both valves. 



Inhabits small streams in South Alabama. Length 2.8 inches. 

 Cabinet of the Academy of Natural Sciences of Philadelphia. 



Shell narrow-elliptical, ventricose or inflated in old shells ; sub- 

 tance of the valves thick before and thinner behind ; posterior dor- 

 sal and basal margin rounded, and the end subangulated; beaks ap- 

 proximate, not very prominent, and with interrupted undulations; 

 concentric lines coarse and prominent ; epidermis very dark olive, 

 and obscurely rayed ; wrinkled on the margin ; cardinal teeth double 

 in both valves, a htde compressed and oblique, and coarsely stria- 

 ted ; cavity most capacious under the umbonial slope ; nacre vary- 

 ing from bluish while to deep salmon color, or purple. 



Observations. This species is remarkable for preferring the small- 

 er streams to the rivers, and is not an uncommon shell in such waters, 

 I found them in company with the U. rubiginosus, Lea, which though 

 not very rare in the small creeks of South Alabama, I never found in 

 either the Black Warrior or Alabama rivers. 



Unio stramineus. pi. 1. fig. 6. 



Shell sub-oval, posterior side wider than the anterior and rounded ; 

 beaks slightly prominent, with irregular undulations ; umbones con- 

 vex ; concentric lines remarkably coarse and prominent ; cardinal 

 teeth double in both valves, and sub-compressed : nacre pearly white 

 and iridescent. 



Inhabits with the preceding species. Length 2.5 inches. Cabi- 

 net of the Academy of Natural Sciences of Philadelphia. 



Shell sub-oval, convex, inflated behind the middle ; posterior side 

 wide and rounded at the end ; posterior dorsal and basal margins ab- 

 ruptly rounded ; umbonial slope disposed to be subangulated ; surface 



