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 XL 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 des 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. .d. N. S. No. 1429. 



OBSERVATIONS. 



Distinguished by its numerous unequal green 

 undulated rays; without these the female might be 



