UN 10. 



171 



Unio radintux, Baknks, Silliiii. Jouni. vi. 205 (young cariosns). — Hildreth, Sillim. 

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

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

 Nat. Sc. vi. 256.— 1)e Kay, Nat. Hist. N. Y. 189, pi. 18, fig. 236. — Gould, Invert. 

 110, fig. 72. 



Uiilo Vinjiniaud, Lam. An. sans Vert. 2d cd. vi. 544. — Deless. Recucil, pi. 1.3, fig. 4. 



Afi/a oblongata. Wood, Snppl. pi. 5, fig. 2. 



Lampailis rndiata, Stimpssox, Shells of New England, 1.3. 



Shell oblong-ovate, broadest and angnlar 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 mannei 

 margin a little an- 



Ffg. 474. 



Hinge- 



U. radiatus. 



Interior 



gular at the beaks ; 

 anterior extremity 

 narrow, about one 

 fourth the length of 

 the shell, regularly 

 rounded, but the 

 liino-e-maro-in turns 

 downwards with a 

 very abrupt curve ; 

 posterior side angu- 

 lar above, rounded 

 at tip ; hinge-margin 



very little compressed ; l)asal margin regularly curved, 

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

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

 a stout ril) l)ehind 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 nowlietter established than the one al)0ve described, 

 though there is good reason to l)elieve that the U. radiatus of Barnes, 

 Dillwyn, Wood, ami perhaps Say, was the young of either f/. cario- 

 sns or U. ochraceaSy or l)()th. It is most likely to ])e confounded 

 with U. sUiquoidciis ; but tluit shell has the epidermis lighter col- 



