164 AMERICAN JOURNAL 



these lines of growth being on each valve; posterior slope 

 long, subangulated, somewhat excavated, and distinctly rayed; 

 beaks rather prominent, with a few rugose undulations at the 

 tips; ligament rather long, slender, pale brown in color; 

 posterior and anterior cicatrices confluent and lightly impressed; 

 nacre silvery white, and delicately iridescent. 



Dimensio7i'i. — Diataeter 1 inch; length 3 inches; breadth 1 J 

 inch. 



Habitat. — Michigan, in Bostwick^s Lake. 



My Cabinet. Cabinet of Hugh Cuming, London. Mus. 

 Comp. Zoology, Cambridge, Mass. Cabinet of George W. 

 Tryon, Jr. 



Ohservations. — A decidedly beautiful species of this inte- 

 resting genus: in form not unlike Anod. pallida, nob., but 

 more ventricose, more solid, darker in color, and the marks of 

 growth are closer and more decided, being quite prominent in 

 old specimens, rendering the shell rough. Like Anod. pallida, 

 it has the green color predominant at the base of the obtuse 

 carina on its posterior end, and two rather marked, broad 

 brown lines between that and the ligament. The nacre is 

 very silvery and somewhat peculiar, in having numerous fine 

 papillas-like pin points scattered over it, which, however, 

 may be only local peculiarity. Altogether, it is one of our 

 most beautiful Anodons. 



