172 



UNIONID^. 



ored, very closely adhering, and perfectly smooth and glossy ; the 

 teeth also are more compressed and more oblique. Mr. Barnes ob- 

 serA'Cs of it that, " amidst a variety almost infinite, like that of the 

 human countenance, there is still a characteristic identity of this 

 species, which can scarcely be mistaken by an experienced observer. 

 One variety of radiatus approaches nearest to this species, but the 

 least appearance of rays forbids its association." This last remark 

 is far from being just. 



Unio cariosus. 



Fig. 72. 



Shell ovate, inflated, not very thick, inequilateral, beaks rather prominent ; epi- 

 dermis yellowish-olive, usually radiated with dark-green ; within usually bluish- 

 Avhite ; teeth compressed, oblique. 



Unio cariosus, Say, Nich. Encyc. (Amcr. cd. 1816) iv. pi. .3, fig. 2. — Barnes, Silliman's 

 Journ. vi. 271. — Lea, Trans. Aniev. Phil. Sue. (new series) vi. 126, pi. 15, fig. 45 

 (animal); Synops. Naiad. 27. — De Kay, Nat. Hist. New York, 193. — Gould, 

 Invert. 1 1 1 , fig. 72. 



Unio cariosa, Lamarck, An. sans Vert. 2d cd. vi. 545. 



Unio ovata, Valenc. Recueil d'Oljs. dc Zool. par Ilumb. et Bonjil. ii. 226, pi. 50, fig. 1. 



Unio cariosus, Conrad, Unionida\ 40, ]d. 19. — Kiister, Siqipl. Cheni. ])1. 24, figs. 1-3. 



Musculus latior subfuscus, cocruleis lineis radiatus, Lister, Conch. 152, fig. 7. 



Lampsiiis cariosa, Stimpson, Shells of New England, 14. 



Shell very variable in form, ovate or rounded, moderately thick, 

 inflated ; beaks placed at the anterior third, rather prominent, usu- 



475. 



U. canosifs. 



ally very much eroded ; hinge-margin straight, ascending from be- 

 fore backwards ; anterior end narrow, regularly rounded ; posterior 

 end regularly curved above and below, and in the male terminating 



