UNIO. 



171 



Unlo radlatus, Barxes, Silliin. Journ. vi. 2G5 (young carioiiHs). — IIildretii, SilHm. 

 Journ. xiv. — Lea, Trans. Anier. Phil. 8oc. iii. 415; vi. 127, pi. 15, figs. 48, 49 (an- 

 imal) ; Synops. Naiad. 25. — Conrad, Uniouidne, 24, pi. 10, fig. 2 ; Synops. Proc. Ac. 

 Nat. Sc. vi. 256. — De Kay, Nat. Hist. N. Y. 189, pi. 18, fig. 236. — Gould, Invert. 

 110, fig. 72. 



Unto Virginiana, Lam. An. sans Vert. 2d ed. vi. 544. — Deless. Recueil, pi. 13, fig. 4. 



il///a oblongata. Wood, Siippl. pi. 5, fig. 2. 



Lampsills radiata, Stuipson, Shells of New England, 13. 



Shell oblong-ovate, broadest and angular behind, beaks near the 

 front, little elevated ; ei)idermis loosely and delicately wrinkled con- 

 centrically, olivaceous, with numerous rays of dusky-green ; some- 

 times the wrinkles are also disposed in a radiated manner. Hinge- 

 margin a little an- 

 gular at the beaks ; 

 anterior extremity 

 narrow, al)out one 

 fourth the length of 

 the shell, regularly 

 rounded, but the 

 hinge-margin turns 

 downwards with a 

 very abrupt curve ; 

 posterior side angu- 

 lar above, rounded u.radmtu,. 

 at tip : hinge-margin 



very little compressed ; basal margin regularly curved. Interior 

 white, iridescent posteriorly, with sometimes bluish ov flesh-colored 

 tints. Cardinal teeth erect, triangular, pyramidal, strengthened by 

 a stout rib liehind the anterior muscular impression. Length, three 

 inches ; height, one and seven tenths inches ; breadth, one and one 

 fifth inches. 



This is one of our common species, and is to be found in most of 

 the large streams and ponds. It is also one of the shells confined 

 to the eastern slope of the range of Alleghanies. 



It exhil)its but little variation in form, except the usual one, 

 that those inhaldted by the female arc broader behind than those 

 inhal>ited l)y the male. 



No species is now better established than the one aliove described, 

 though there is good reason to believe that the U. radiatns of Barnes, 

 Dillwyn, Wood, and perhaps Say, was the young of either U. cario- 

 siis or U. or/iraceiis, or both. It is most likely to 1)0 confounded 

 with U. isiliquuideiis; but that shell has the epidermis lighter col- 



