II 



SYNONYM ES 



U. nn atis, Say. Nicaotaon'a Km yclopedim, third American 

 edition, articW- Conchology. 



I . r iKiPi.u ATI ■-. Aam. \n. sans. Vert., vol. ii. p. 71. 



OBSERVATIONS 



This shell is most neari) related to V. hcros. Say, 

 and /'. costatus, Rat. It differs from l>oth in baying 

 fewer folds and a much more prominent umbo. 

 There is no trace of the fine plica? on the uml>o, 

 which so distinctly characterize ( . hems. 



Inhabits the Ohio and its tributaries. I have a 

 remarkably large and perfect specimen, presented by 

 Richard C. Taylor, Esq., who found it with many 

 others in St. Peter's n\» r. Wisconsin. 



I MO CARDIIM. 

 Plati LXVI. 



DESCRIPTION. 



Shell with the posterior side very broad, subtrun- 

 cate; anterior side rapidly narrowed, subangulated; 

 disks very convex; umbones large, rounded, elevated; 

 beaks recurved over the ligament; ligament large and 

 prominent, passing under the beaks; posterior lunule 

 depr e ss ed at tin- margin, fuscous, broad-lieart-sha[)ed, 

 longitudinally waved; lunge margin depressed between 

 the beaks; epidermis yellow ish-ohve, becoming chest- 



