452 new genus and s03ie new species 



6. Symphynota Gracilis. 



Testa sub-triangulari-ovatd, incBquilaterali, transversim rugosa, sub- 

 compressd ; valvulis tenuibus fragilibusque ; margine postei'iori dorsali 

 sub-alatd, connatdque ; dente cardinali in valvuld dextrd elevato, recurvo ; 

 natibus sub-proniinulis ; ligamento celato ; margarita violaceo-purpured 

 et iridescente. 



Shell sub-triangular-ovate, inequilateral, transversely wrinkled, rather 

 compressed; valves thin and fragile; posterior dorsal margin connate, 

 wing but little elevated; cardinal tooth of right valve elevated, recurved; 

 beaks scarcely prominent; ligament concealed; nacre pearly, violet- 

 purple, and iridescent. 



„ , C Ohio. T. G. Lea. 

 ^^^' I Wisconsan. Mr Schoolcraft. 



My Cabinet. 



Cabinet of Mr Barnes. 



Cabinet of Prof. Vanuxem. 



Cabinet of P. H. Nicklin. 



Cabinet of Mr Swainson. 



Cabinet of the New York Lyceum. 



Cabinet of the Academy of Natural Sciences. 



Unio gracilis. Barnes. Silliman's Amer. Journ. Vol. VI. 



p. 174. 



Unio fragilis. Swainson*. 

 Unio planus. Barnes. 

 Diam. 1 — 1-2, Length 2-2 — 2-5 inches. 



Breadth 3-1 — 4-1 inchesf. 



Shell sub-triangular-ovate, inequilateral, transversely wrink- 

 led, rather compressed ; substance of the shell thin ; valves ele- 

 vated into a small wing over the ligament and connate ; beaks 

 slightly prominent, pointed, having two or three minute ele- 

 vations ; ligament concealed in the wing ; epidermis yellow- 



* I have retained the specific name of Mr Barnes in preference to that of JNIi- 

 Swainson in the right of priority. Mr B. pubUshed in January 1823. Mr S.'s 

 dedication of 3d vol. of his Zool. Ulus., in which the fragilis is described, is dated 

 Oct. 1823. 



t See Barnes's description. 



