family unionid.e — anodon. 201 



Anodon edentula. 



PLATE XVI. FIG. 831. 



(STATE COLLECTION.) 



Alasmodonta edentula. Say, according to Lea. 



Margarita (Anodonta) id. Lea, Trans. Am. Phil. Soc. Vol. 6, p. 136. 



Anodon areolatus. Swainson, Zool. Illustrations, 2d series, pi. 1. 



Description. Shell moderately thin, inequilateral, snbcompressed, regularly rounded at one 

 extremity and subangular at the other : dorsal margin nearly straight. Beaks prominent, 

 contiguous, often decorticated, strongly rugose. Basal margin not regularly rounded: a 

 slightly emarginate prominence supplying the place of a tooth in one valve. 



Color. Epidermis light brown, with indistinct traces of radiation : within, salmon-color 

 near the beaks ; bluish white and faintly iridescent towards the margins. 



Vertical axis, 1-0; transverse ditto, 1*7. Diameter, 0*7. 



I am scarcely satisfied with the propriety of separating this from Alasmodon, and unfortu- 

 nately I have but one specimen, obtained from Lake Onondaga. Mr. Say's description I 

 have not met with. 



Anodon plana. 



PLATE XVII. FIG. 232. 



(STATE COLLECTION.) 

 Anodonta plana. Lea, Trans. Am. Phil. Soc. Vol. 5, p. 48, pi. 7, fig. 18. 



Description. Shell large, solid, inequilateral, inflated, elliptical, produced and attenuated 

 in front : ligament external, elevated. Beaks large and prominent, often eroded. Surface 

 concentrically rugose, almost scaly on the smaller end : cavity within large and deep. Cica- 

 trices distinct. 



Color. Epidermis dark brown, occasionally light green : within bluish white and purple, 

 iridescent ; often a light salmon-colored tinge in the centre. 



Vertical axis, 2.7; transverse ditto, 4 "5. Diameter, 1*7. 



The specimens which furnished this description came from Port bay, Lake Ontario. Through 

 the attention of Mr. I. Cozzens, I have examined forty or fifty specimens of this species from 

 Ohio ; these are generally much larger, more inflated, with thicker valves, and the alation 

 more conspicuous. I should be disposed to consider our New-York specimens as very strongly 

 marked varieties of this species. 



Fauna — Part 6. 26 



