ANODONTA. 41 



waters ; and Baudon has also noticed the same circum- 

 stance in the De*partement de I'Oise. All these cases 

 would lead us to infer that there exist at least two 

 distinct species of Anodonta in the North of Europe ; 

 and I am only at present prepared to go to this extent. 

 At the same time, I do not dispute the claims of other 

 forms to specific rank. It would be unseemly, as well 

 as unjust, thus to depreciate the labours of those 

 naturalists who have so ably and carefully endeavoured 

 to solve this perplexing problem ; and there is quite as 

 good reason for believing that their views as to the ex- 

 tension, are as correct as ours as to the reduction, of the 

 specific line. Although, therefore, I only propose to 

 admit two old Linnean species (A. cygnea and A. ana- 

 tina), some at least of the varieties hereafter indicated 

 may be considered distinct species by those of my readers 

 who from experience or choice may be inclined to take 

 another view of the case. 



1. ANODONTA CYG'NEA*, Linne. 



MytHuscygneus, Linn. Syst. Nat. ed. xii. p. 1158. A. cygnea (partly), 

 F. & H. ii. p. 155, pi. xl. f. 2, 3, & xli, and (animal) pi. Q. f. 3. 



BODY grey, with a yellowish or reddish tint : mantle bor- 

 dered with tawny-brown : foot large, broad, dirty-yellow, with 

 a tinge of orange or red : gills grey, with occasionally a reddish 

 hue, of a gauze-like texture : labial palps broadly triangular. 



SHELL oblong, rather ventricose, thin, moderately glossy, 

 yellowish-green or brown, transversely and irregularly grooved 

 by the lines of growth, and wrinkled in the same direction on 

 the posterior and lower sides : epidermis thin : beaks straight, 

 placed at a distance of about one-fourth from the anterior ex- 

 tremity : umbonal region compressed, strongly plaited : liga- 

 ment rather long, strong, partly concealed within the over- 

 lapping edges of the upper margin or hinge-line, which is 

 straight : anterior side not gaping, rounded, and abruptly 



* Belonging to (e. g. food for) swans. 



