26 



on the bank of Elk river, Alabama, in which the epi- 

 dermis was dark and the rays obscure. Mr. Lea 

 compares it with the crassus, Say, but we cannot 

 find any point of resemblance. 



UNIO FASCIOLUS. 



Plate XI. — Fig. 2. 

 DESCRIPTION. 



Male. Shell elliptical, inflated, yellowish, with nu- 

 merous unequal flexuous green rays; anterior margin 

 regularly, not obtusely rounded; posterior extremity 

 angulated; ligament margin slightly declining; umbo 

 wide, prominent; beaks retuse, distant from the an- 

 terior extremity; umbonial slope obtusely rounded; 

 within white; cardinal teeth prominent, diverging; 

 margin horn-coloured, shewing the exterior rays. 



Female. Short ovate; posterior side dilated; umbo 

 narrower and more oblique; ligament margin elevated. 



SYNONYMES. 



U. fasciolus. Raf. An. gen ties Phys. Sec. vol. 5. p. Poul- 

 son's trans, p. 28. Say. Amer. Conch. No. 6. 



U. multiradiatus, Lea. Trans. Amer. Philos. Soc. new series, 

 vol. 3. p. 48. pi. ix. fig. 15. 



Cab. Ji. N. S. No. 1429. 



OBSERVATIONS. 



Distinguished by its numerous unequal green 

 undulated rays; without these the female might be 



