105 



from beak to base; beaks rather distant from the 

 anterior extremity, eroded; umbo very broad; umbo- 

 nial slope abruptly rounded, nearly terminal; posterior 

 slope with slightly prominent radiating lines; poste- 

 rior margin nearly direct; margin of the tip obtuse; 

 epidermis wrinkled, yellowish brown, with capillary 

 rays over the umbo; within white; cardinal teeth 

 direct, robust; lateral teeth short, rather thick, very 

 distant from the cardinal teeth. 



OBSERVATIONS. 



This small species has considerable resemblance 

 to U. interruptus, but the disks are less flattened, the 

 posterior slope much less depressed and wider, the 

 base more arcuated, and it is destitute of distinct 

 dotted rays. I found a few specimens in the Black 

 Warrior river, near Blount's Springs, Alabama. 



UNIO CUNEUS. 



Plate LVIII.— Fig. 1. 



DESCRIPTION. 



Shell obliquely cuneiform, very thick; diameter 

 through the umbones profound; disks flattened be- 

 hind the middle, and descending wedge-shaped to 

 the posterior extremity, which is obtuse; beaks much 

 eroded, terminal; umbo broad and very prominent; 

 umbonial slope rounded; epidermis dark reddish- 

 brown, rough and much wrinkled; within pink; car- 



