21 



UNIO GLANS. 



Plate IX. — Fig. 2. 

 DESCRIPTION. 



Shell ovate-elliptical, thickened anteriorly; surface 

 with numerous concentric lines; anterior side short; 

 posterior side subcuneiform; umbo slightly prominent; 

 beaks undulated; umbonial slope undefined; epidermis 

 generally dark brown, sometimes rayed; within dark 

 purple, except on the anterior margin; cardinal teeth 

 prominent, direct. 



SYNONYMES. 



U. glans, Lea. Trans. Amer. Philos. Soc. new series, vol.iv. 



pi. viii. fig. 12. 

 Cab. d. N. S. No. 1168. 



OBSERVATIONS. 



This does not appear to be an abundant species, 

 yet it is occasionally found in the waters of Ohio, 

 Tennessee and Alabama. In the latter state I met 

 with it only in the tributaries of the Tennessee river. 

 The purple nacre and white anterior margin will al- 

 ways distinguish this species from any other, which 

 resembles it in form. Another peculiarity is the 

 posterior tooth of the left valve pointing to the pos- 

 terior extremity, which causes the teeth to diverge 

 greatly. It most resembles U. licnosus, nob. and U. 

 parvus, Barnes. The figure represents the largest 

 and best specimen I have seen, and the only one that 

 is distinctly rayed; it is from the Harpeth river, 

 Tennessee. 



