UNIO. 



171 



Unio radiafus, Barnes, Sillini. Jonni. vi. 2()5 (younjj; cariosns). — Hildretii, Sillim. 

 Journ. xiv. — Lea, Trans. Ainer. Phil. Soc. iii. 41.'3 ; vi. 127, pi. If), ligs. 48, 49 (an- 

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

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

 110, fig. 72. 



Unio Virginiana, Lam. An. sans Vert. 2(1 cd. vi. 544. — Deless. Recueil, pi. 13, fig. 4. 



Mija oblongata. Wood, Suppl. pi. 5, fig. 2. 



Lampsilis radiata, Stimpson, Shells of New England, 13. 



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

 front, little elevated ; epidermis 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, about one 

 fourth the length of 

 the shell, regularly 

 rounded, but the 

 hinge-maririn turns 

 downwards with a 

 very abrupt curve ; 

 posterior side angu- 

 lar above, rounded 

 at tip ; hinge-margin 



very little compressed ; basal margin regularly curved. Interior 

 white, iridescent posteriorly, with sometimes Iduish or flesh-colored 

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

 a stout rib behind 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 exhibits but little variation in form, except the usual one, 

 that those inhabited by the female are broader behind than those 

 inhabited by the male. » 



No species is now better estalilished than the one above described, 

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

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

 sns or U. ochraceiis^ or l)oth. It is most likely to be confounded 

 with U. sUlquoideus ; l)ut that shell has the epidermis lighter col- 



U. radiatus. 



