﻿ANODONTA 435 



I suspect that this is a young- shell, but the rhomboid form 

 and the difference between the smoothness of the anterior and 

 posterior parts of the shell would seem to distinguish it from 

 other species. 



Anodonta K£;nnicottii Lea. 



Shell long', elliptical, ovate or subrhomboid, inequilateral, 

 convex, stroug, with a well-developed, rounded or subangiilar 

 posterior ridge, which curves upward in the middle, is rarely 

 double, and ends in a blunt point below the median line; beaks 

 almost conpressed, elevated but little above the dorsal line, 

 rather sharp, their sculpture consisting of uneven, somewhat 

 doubly-looped, nodulous ridges, surface scarcely smooth, dull 

 greenish or ashy-brown, exhibiting the rest periods quite dis- 

 tinctly ; nacre dirty bluish-white. 



Length 107, height 54, diam. 32 mm. 



Length 80, height 47, diam. 31 mm. 



Upper and middle St. Lawrence River System ; northwest 

 into the Mackenzie drainage. 



Type locality, Fort Rae, Great Slave Lake and north end 

 of Lake Winnipeg. 

 Anodonta kennicottii I,ea, Pr. Ac. N. Sci. Phila., V, 1861, p. 



56 ; Jl. Ac. N. Sci. Phila., V. 1862, p. 214, pi. xxxiii, fig. 283 ; 



Obs., IX, 1S63. P- 36, pi- XXXIII, fig. 283. — Clessin, Conch. 



Cab. Ano., 1874, p. 153, pi. xlix, figs. 3, 4. — Simpson, Syn., 



1900, p. 647. 

 Margaron f Anodonta) kennicottii Lka, Syn., 1870, p. 78. 

 Anodonta simpsoniana Lka. Pr. Ac. N. Sci. Phila., V. 1861, 



p. 56; Jl. Ac. N. Sci. Phila., V, 1862, p. 212, pi. xxxii, fig. 



281 ; Obs., IX, 1863, p. 34, pi. xxxii, fig. 281. — Clessin, 



Conch. Cab Ano., 1874, p. 119, pi. xxxvii, figs. 5, 6. 

 Margaron (Anodonta) simpsoniana Lea, Syn., 1870, p. 78. 

 Anodon simpsonianns Sowkrp.y, Conch. Icon., XVII, 1870, pi. 



xxxvTi, fig. 153. 



A form, which seems to be confined to the upper St. Law- 

 rence and Arctic drainage. It is ver\' variable, some speci- 

 mens being evenly ovate, others long elliptical, and still others 



