UNio. 1G9 



color ; but I have a scries of a strongly marked variety from the 

 Sliawsheen River in Andover, Avhere the color is dark chestnut with 

 considerable lustre, the young shells are radiated with dark lines 

 almost as much as U. radicUus, and some of the old shells arc very 

 coarsely })laited from the beaks downwards into parallel folds. 



The only New England species with which this is liable to be 

 confounded are U. nasidus and U. radiatiis. The first dithers, ex- 

 ternally, in its more smooth, greenish, and somewhat radiated epi- 

 dermis ; the angular ridge running from the beaks backwards, pro- 

 duced by the strong compression of the hinge-margin ; and l)y a 

 contraction of the basal margin, near its posterior termination, so 

 as to form a sort of beak ; and internally by the silvery, iridescent 

 nacre, and the slender, very oblique, cardinal teeth. U. radiatiis has 

 the hinge very nearly the same as U. coniplanatus ; Init the luicre 

 is white, or somewhat livid, the shell never becomes so large, is 

 more regularly convex ; the epidermis is nearly smooth, shining, 

 and yellowish-green, with conspicuous rays of olive color. 



Unio nasutus. 



Fig. 71. 



Shell transversely oblong-lanceolate, hinge-margin compressed, anteriorly 

 rounded, posteriorly somewhat beaked ; epidermis dusky-green, obscurely rayed ; 

 cardinal teeth compressed, oblique ; nacre very bright, bluish- white, iridescent. 



Unio nasutus, Say, Nich. Eiicyc. (Amer. 1st cd.) iv. pi. 4, tig. 1 (1816). — Conrad, 

 Unionidre, 38, pi. 18, fii;-. 1 — De Kay, Nat. Hist. New York, 191, pi. 20, tig. 239. 

 — Lea, Synops. 37. — Coniiad, Synops. in Proc. Ac. Nat. So. vi. 252. 



Mija nasuta, Wood, Index, Suppl. pi. 1, fig. 4. 



Unio roslratus, Valenc. Kccueil d'Obs. de Zool., &c., par Ilumb. ct Bonpl. ii. 233, pi. 53, 

 fig. 3. 



Eunjnca nasuta, Stimpsox, Shells of New England, 13. 



Lister, Conch, t. 151, fig. 6. 



Shell slender, oljlong-lanceolate, very inequilateral ; ])eaks small, 

 pointed, and slightly elevated ; hinge-margin straight to more than 

 half the distance from the beaks to the posterior end, when it sud- 

 denly declines and continues straight to the point ; lower margin 

 nearly parallel with the u{»per, though somewhat rounded at the 

 middle, and toAvards the end turns rapidly U})ward towards the 

 point, which is considerably produced, so as to form a sort of snout. 

 An angular ridge passes backwards from the beaks to the tip, aliove 

 which the shell is very much compressed ; two or more radiating 

 furrows are usually seen traversing this portion. Surface rather 

 smooth, not much wrinkled by the lines of groAvth. Epidermis 



