34: AMERICAN CORBICULAD^. 



Long. 0.68; Lat. 0.43; Diam. 0.31 inches. 

 Hah. North America, in the New England States, in the States of New- 

 York, New Jersey, Pennsylvania, Ohio, Michigan, Wisconsin, Iowa, Minne- 

 sota and Alabama, and in Canada. (Cabinets of the Academy of Natural 

 Sciences of Philadelphia, Smithsonian Institution, Garden of Plants in 

 Paris, Museum Delessert, Jay, Prime and others.) 



Cyclas sulcata, Lamarck, An, s. vert. V, 1818, 560. 



Cj/clas saratogea, Lamakck, loc. sub. cit. V, 1818, 560. 



Cyclas similis, Say, Nich. Encycl. Amer. edit. IX, 1818, pi. 1, f. 9. 



Cyclas las7nampsis, Rafinesque, II. scie. Phys. IX, 1820, 319, pi. 82, 



f. 19, 20. 

 Cyclas solida, DeKay, Kept. 1842, 220, pi. xxv, f. 265, 

 Cyclas gigantea, Prime, Bost. Proc. IV, 1851, 157. 

 Cyclas ponderosu, Pkime, loc. sub. cit. IV, 1851, 157. 

 Cyclas siriatina, Lamarck, Fer. in Mag. Zool. 1835. 

 Cyclas rhomboidea, Say, C. B. Adams, Vermont cat. 1842, 18. 



This, our most common aud widely distributed species, living 

 as it does in so many difi'ereut sections of the country, presents at 

 times great variations in size, color and general appearance. It 

 can, however, be easily recognized by its very elongated and equi- 

 lateral form, and by the beaks which are uniformly full and con- 

 vex ; they are often eroded.' The young is often of an uniform 

 light lemon color, which, as the shell matures, becomes gradually 

 darker from the beaks downwards until the new shade covers the 

 whole surface of the shell ; in certain intermediate stages of growth, 

 the shell is marked with a zone of yellow on the inferior margin ; 

 the color of the adult varies from a greenish-brown to a dark 

 chestnut. The young shell has at times, owing to the variations 

 which exist between it and the adult, been taken for a different 

 species; by some it has been taken for the S. rhomboideum. 



The hinge-margin is generally straight. I have specimens, 

 however, from Alabama, Pennsylvania and Rhode Island, in 

 which it is slightly curved. One of the distinctive characters of 

 this species is that the lateral teeth are never placed at an angle 

 with the cardinal teeth ; they are generally on a straight line with 

 them. 



The finest specimens I have seen of the S. sulcatum were sent 

 to me by Mr. Ingalls, who had collected them in Washington 

 County, New York ; they were remarkably convex, and measured 

 as much in length as jf of an inch ; the beaks were very full, and 

 much raised above the margin of the shell. 



