76 



It most nearly resembles U. cariUum, Raf., but the 

 tumid umbones will always prove a destructive cha- 

 racter. Dr. Green was the first to recognise this as 

 an undescribed species, and his name, having priority, 

 must necessarily be adopted. He observes, "I now 

 describe a fine large shell, which seems to have 

 escaped the notice of our conchologists. The first 

 specimens of this shell which I observed were from 

 the Falls of St. Anthony. I afterwards received it 

 from the Bayou Teche, but I never discovered or 

 ascertained that it exists in the Ohio." Mr. Lea, on 

 the authority of Col. Long, informs us that it inhabits 

 the Ohio, 150 miles below Louisville, Ky. 



UNIO RUDIS. 



Plate XLIII.— Fig. 1. 



DESCRIPTION. 



Shell ovate-acute, thick anteriorly; diameter great- 

 est at the umbones; beaks eroded; posterior side 

 cuneiform; ligament and posterior margins arcuate, 

 extremity subangulated; epidermis brown, wrinkled 

 inferiorly; within white; cardinal teeth small, direct; 

 lateral teeth slightly arcuate. 



SYNONYME. 



TT. ravenelianus, Lea. Trans. Amer. Phil. Soc., new series, vol. 



iv. p. 144, pi. iii. fig. 5. 

 Cab. .tf. N. S. No. 20415. 



OBSERVATIONS. 



Inhabits French Broad river, North Carolina, Dr. 



