﻿388 ANODONTA 



came from the fresh waters of Europe, and is allied to anatiria. 

 and it is ([uite likely it is .-/. cyi^tiea. As there can be no doubt 

 about Say's species. 1 think it best to use his name. 



It is an abundant, widely distributed and variable species. 

 As a rule the shell is smoother, thinner and less distinctly bi- 

 ang-ulate liehind than the nearly related .1. implicata. The 

 latter, when adult, nsually becomes (|uite solid anteriorly, 

 though not always, and the nacre turns to flesh-color, pale 

 lurid purple or dull salmon. Ikit there are many specimens, 

 which can scarcely be said to be either one or the other. A. 

 virgulata is a southern form of this species, which is perhaps a 

 little brig-hter colored than the majority of northern specimens, 

 but it hardly seems to be w^orthy of varietal rank. , /. linlliamsii 

 and ./. tr\'0)iii are also slight variations, but I do not think 

 them any more worthy of specific or varietal rank than several 

 other manifestations of this s])ecies. 



Anodonta margixata Say. 



Shell long elliptical or long ovate, subinflated, inequilateral, 

 thin ; beaks raised a little above the dorsal line, subcompressed 

 to moderately full, their sculpture consisting of a number of 

 irregular, line, somewhat doubly looped, often wavy bars; pos- 

 terior ridge low, rounded or faintly double, ending behind 

 about midway up from the base in a rounded or slightly bi- 

 angulate point ; surface with irregular growth lines, wdiich 

 sometimes become concentric ridges ; epidermis ashy-olive- 

 greenish or brownish, often with narrow% darker bands, es- 

 pecially at the rest periods, rarely faintly rayed ; nacre bluish- 

 white with a peculiar dull, silvery tint, often yellowish or sal- 

 mon in the cavities, somewhat iridescent behind. 



Length 132, height 65, diam. 43 mm. 



Length 120. height 55. diam. 45 mm. 



Length 85, height 40, diam. 30 mm. 



St. Lawrence River drainage. 



Type locality not given. 

 Anodonta iiiarginata S.w. Xich. Kncyc, 11. 1S17. i)l. in. fig. 5. 

 Aiuninnta marginatus TTam.kv, Riv. Shells, 1S43. p. 217. 



