448 NEW GENUS AND S03IE NEW SPECIES 



3. Symphynota Alata. 



Testa ovato-triangulari, transversim rugosd, sub-compressa ; valvulis 

 crassiusculis, earum marginibus dorsalibus alatis, et super ligamento 

 connatis ; dente cardinali in valvulis ambabus duplici, latei'ali in sinis- 

 tra tantum duplici, subcurvato; ligamento sub aid celato; natibus pro- 

 minulis ; margaritd purpuredj 



Shell triangular-ovate, transversely wrinkled, rather compressed ; 

 valves moderately thick, elevated into a high wing, and connate over the 

 ligament ; beaks scarcely prominent ; cardinal tooth double in both 

 valves ; lateral tooth double in the left valve only, and slightly curved; 

 ligament concealed ; nacre purple. 



Hab. our western waters. 



Unio alatus. Say. Nicholson's Encyclopaedia (Am. Ed.) 

 Art. Am. Conch, pi. 4, fig. 2.* 



Unio alata. Lamarck. 



Unio alatus. Barnes. Silliman's Am. Journ. Vol. VI. 



Unio alata. Swainson. 

 Diam. 2, Length 4'7, Breadth, 6-9 inches.f 



Remarks. — In young specimens it appears disposed to be 

 connate anteriorly to the beaks also. The dorsal cicatrices 

 form quite a row across the cavity. 



4. Symphynota Complanata. 



Testa ovato-triangulari, inaquilaterali, transversim rugosd, compres- 

 sd; valvulis crassis; mar gine posteriori dorsali alata connatdque ; dente 

 unico cardinali in valvuld utrdque; piano irregulari calloso sub liga- 

 mento ; natibus compressis, sub-prominulis ; ligamento celato ; marga- 

 ritd alba, iridescenti. 



Shell triangular-ovate, J inequilateral, transversely wrinkled, com- 



* This figure was made from an imperfect specimen, the wing being mutilated, 

 t See Barnes's description. 



l Mr Barnes says " ovately quadrangular ;" but the shell is evidently more tri- 

 angular., as his figure displays it. See SilUmari's Am. Journ. Vol. VI. p. 278. 



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