OF CONCHOLOGY. 159 



nent, undulate and rugose at tip; anterior cicatrices distinct 

 and well impressed ; posterior cicatrices indistinct and con- 

 fluent ; marks of growth widely separate and very distinct, 

 about three on each valve ; nacre bluish-white and iridescent. 



Sahitat. — Michigan. 



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

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

 Tryon, Jr. 



Observations. — A fine, large species, and more robust than 

 is usual in this genus. May be compared with AnoJon plana, 

 Lea, but is less inflated and of lighter color. It is also 

 decidedly biangulated, which cannot be said of A. plana, and 

 it is also more depressed than Mr. Lea's species. May, per- 

 haps, better be compared with Anod. Daniel-sit, Lea, but seems 

 to be larger, less inflated, and lighter colored, as well as more 

 robust. 



Anodox imbricata, Anthony. — t. 1-i, f. 1. 



Description. — Shell elliptical, somewhat inflated, inequilate- 

 ral; substance of the shell rather thin; epidermis brownish- 

 olive, darker on the posterior slope; beaks elevated, recurved, 

 wrinkled; marks of growth crowded, darker in color than the 

 general hue ; ligament short, thin, brown ; nacre silvery white 

 and iridescent. 



Habitat.— CamT^ Lake, Michigan, 



My Cabinet. Cabinet of PI. Cuming, London. Mus. Comp. 

 Zoology, Cambridge, Mass. 



Observations. — This species need not be confounded with 

 any other ; its graceful form and peculiarly rough, imbricated 

 surface will readily determine it. The marks of growth are 

 decidedly elevated, and are particularly close to each other 

 near the basal edge. The roughness caused by these closely- 

 set, projecting, concentric lines, will at once show the propriety 

 of the specific name. The beaks are beautifully recurved, 

 showing a long, narrow lunule. 



AxoDOX OPALINA, Anthony. — t. 14, f. 2. 



Description. — Shell smooth, inflated, elliptical, inequilateral, 

 rather thin ; epidermis yellowish, with rather distant marks 

 of growth, about tliree on each valve ; beaks prominent, with 

 beautiful, fine undulations at tip; ligament long, slender, 

 brownish yellow ; anterior slope rounded, posterior slope sub- 

 truncate and biangular, with one or two impressed lines near 

 the ligament ; nacre silvery white and iridescent. 



