OP CONCHOLOGY. 161 



Dimensions. — Diameter 1| inches ; length 3f inches ; breadth 

 If inches. 



HaMtat. — Michigan. 



Mj Cabinet. Mus. Comp. Zoology, Cambridge, Mass. 

 Cabinet of George W. Try on, Jr. 



Observations. — Eesembles Anod. Dariensis^ Lea, in form, but 

 is rather larger in proportion to its width, lighter in color, and 

 the lines of growth are more distant and more distinct, while 

 the whole epidermal surface is less uniform in color. The 

 marks of growth are unusually distant, dark in color, rather 

 broad, and seldom more than two on each valve, even of a 

 large specimen. The posterior end is only slightly angulated, 

 the angle nearest the ligament being the most distinct, and the 

 surface there is usually lighter in color than on the umbones 

 or the anterior part of the shell. Altogether, it is a graceful 

 and beautiful species. 



Anodon papyracea, Anthony. — t. 15, f. 2. 



Description. — Shell smooth, elliptical, inequilateral, very 

 thin; epidermis brownish-olive, with obscure, dark rays; 

 beaks prominent, recurved, minutely rugose at tip ; rounded 

 before and angular behind ; marks of growth very distant, 

 and not very prominent ; anterior and posterior cicatrices both 

 confluent ; nacre dirty yellow under the beaks, but this color 

 does not extend beyond the middle of the valve, the lower 

 portion being of a dull bluish-white color. 



Habitat. ? 



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

 Comp. Zoology, Cambridge, Mass. 



Observations. — This is not a very showy species, but, never 

 theless, rather an interesting one. Its dull, dark olive color 

 and short, quadrate form may be sufiicient to distinguish it 

 from its congeners. In its general form, it approaches a Bra- 

 zilian species, Anod. obtusa, Spix, but is thinner, more trun- 

 cate, and less inflated. Old specimens are rather coarsely striate, 

 and much darker in color. The species is always very thin, and 

 uniformly so, being never thickened anteriorly, as most Ano- 

 dons are. The beaks of this species are unusually prominent 

 and recurved, with a very decided lunule. 



