172 



unionidj:. 



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

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

 serves of it that, " amidst a variety almost infinite, like that of the 

 hmnan countenance, there is still a characteristic identity of this 

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

 One variety of radlatus approaches nearest to this species, Init 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- 

 white ; teeth compressed, oblicpie. 



Uniu C'iriosns, Say, Nicli. Encyc. (Amcr. ed. 181G) iv. pi. .3, fip:. 2. —Barnes, Silliman's 

 Joiiru vi. 271. — Lea, Trans. Aiii-or. Phil. Soc. (new scries) vi. 126, pi. 15, fit;-. 4.') 

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

 Invert. HI, fig. 72. 



TTiilo cariosa, Lamarck, An. sans Vert. 2d cd. vi. 54,5. 



Unit) omita, Valenc. Reciieil d'Obs. ds Zool. par Humb. et Bonpl. ii. 226, pi. 50, fig. 1. 



Unio cariosus, Conrad, Unionid;c, 40, pi. 19. — Kuster, Suppl. Chcm. pi. 24, figs. 1-3. 



Arusrulus latior snh/iisriis, creru/eis lineis rmliatiis, Lister, Conch. 152, fig. 7. 



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



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

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



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

 fore l)ackwards ; anterior end narrow, regularly rounded ; posterior 

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



