27 



OBSERVATIONS. 



This shell is related to U.fasciolaris, Raf. but is 

 shorter, more elliptical and convex, and is readily 

 distinguished; it cannot be confounded with U. faa- 

 ciata, Raf. as that species is broad and angular be- 

 hind, compressed, and irregularly rayed. 



Inhabits Flint river, Morgan county, Alabama. 

 UNIO TRABALIS. 

 Plate III.— Fig. 5. 



DESCRIPTION. 



Sliell narrow-elliptical, subrostrated; thick before, 

 and very thin on the posterior margin, which descends 

 rectilinearly and very oblique; end margin obtusely 

 rounded; umbones broad and prominent; beaks 

 eroded; epidermis dark olive brown, rayed; within 

 white, and highly iridescent on the posterior side. 



OBSERVATIONS. 



This shell has almost the form of U. nasuius, ex- 

 cept that the umbones are far more prominent, and 

 the rostrum is nearly on a line with the base; the 

 habit is altogether different from that shell. Perhaps 

 it may approximate U. siihrostratus, Say, a species 

 I have not seen; but it differs from the description in 

 being remarkably thick on the anterior portion of the 

 shell. 



