: ANODON. 



Aiiodonta. Lam, 



TESTA gequivalvis, inaequilatera, transversa, 

 plerumque tenuis, epidermide viridi induta. 

 Car do edentulus, Ligamentum externum, elon- 

 gatum. Impressiones musciilares duse, postica 

 composita. 



In consequence of their not having any teeth, Linne 

 placed the shells which compose the present Gemis among 

 his Mytili, and for the same reason Lamarck, rightly 

 separating it from Mytilus, constituted a new Genus under 

 the name of Aiiodonta, hut Anodon^ is now generally 

 adopted as heing the more correct term. There is such a 

 gradual transition from those shells that may be con- 

 sidered as decidedly Anodontes, to Lamarck's Co7iques 

 Jluvixitiles through Unio, Hyria, Iridina, Megadesma,t &c. 

 that in some instances it is difficult to determine in which 

 Genus a shell ought to he placed: we have, therefore, 

 taken care to figure one of those that, possessing soriie of 

 the characters that are commonly considered as more 

 appropriate to Unio, are, nevertheless, united to Anodon, 

 in consequence of the absence of teeth : it is in fact an 

 intermediate shell, and forms, with many other similarly 

 circumstanced species, a decided link in Nature's chain of 



* Leach and Bowdich were the first to alter the generic name from Anodonta. 

 to Anodon: this has been done at the suggestion of our learned friend the Rev. 

 Dr. Goodall, to whom we most gratefully acknowledge our obligations for many 

 useful hints respecting nomenclature. 



t Our Potaraophila; Lamarck's Galatea. 



