96 DESCRIPTION OP NEW 



sembles U. capsxformis (nobis), but that shell is elliptical while this is 

 oblique. 



I owe to Dr Kirtland a fine suite of male and female specimens, and 

 it was the examination of these which induced me to assign a distinct 

 place for it among the species. 



I name it after an ardent student of the Mollusca, Mons. Sander 

 Rang. 



Anodonta Pepinianus. Plate XVI. fig. 51. 



Testa trapezia simili, inqceuilaterali, transversa; valviilis tenuibus ; natibus prominentibus ; 

 clivo umboniali subelevato; epidermide striata; margarita alba. 



Shell irapezoiclal, inequilaieral, transverse; valves (hin; beaks prominent; nmbonial 

 slope rallier elevated; epidermis striated; nacre white. 



Hab. Lake Pepin, Portage County, Ohio. B. Tappan, Esq. 



My Cabinet. 



Cabinet of Judge Tappan. 



Diaiu. -7, Length 1*2, Breadth 2 inches. 



Shell trapezoidal, rather inflated, flattened on the sides, carinate be- 

 hind, inequilateral, transverse ; substance of the shell thin ; beaks pro- 

 minent; umbonial slope rather elevated and rounded ; epidermis trans- 

 versely striated, with the lines of growth strongly marked and appa- 

 rently without rays. Anterior and posterior cicatrices both confluent ; 

 dorsal cicatrices in the centre of the cavity of the beaks ; cavity of the 

 shell rather deep ; cavity of the beaks rather deep ; nacre white. 



Remarks. — I owe this shell to the kindness of my friend. Judge 

 Tappan, who informs me that has observed it only in Lake Pepin. In 

 its colour, and being fragile, it resembles the An. fragilis (Lam.). It 

 may be distinguished from any of our species by its trapezoidal out- 

 line. The two specimens in my possession, are both in the nacre slightly 

 iucrusted with yellow spots. The smaller one being young and having 

 the beaks perfect, exhibits numerous fine undulations at the tip. 



The specimen represented is of the largest size which Judge Tap- 

 pan has seen. 



