OF CONCHOLOGY. 113 



Habitat — Grattan, Mich., (C. M. Slayton, Esq.) My Cabi- 

 net. Cabinet of Academy of Natural Sciences. 



Observations. — Differs from 31. rufa, Hald., by its smaller 

 size, more rounded Avhorls, and its uniformly rhombic outline. 



Anodonta subcarinata, Currier. — Plate 6, fig. 5. 



Description. — Shell smooth, elliptic, rounded before, biangu- 

 late behind, and very inequilateral ; epidermis bright yellow, 

 with numerous faint green rays over the entire surface; lines of 

 periodic growth well defined by a brighter yellow, from which 

 spring numerous arborasform, raised markings on the anterior 

 basal portion ; two well-defined flat carinse radiate from the 

 umbones to the angle of posterior margin; substance of shell 

 thin ; nacre silvery white and very iridescent. 



Habitat. — Pentwater, Oceana County, Mich, (J. A. McNiel, 

 Esq.) Cabinet of J. A. McNiel. Cabinet of the Academy of 

 Natural Sciences, Philadelphia. 



Observations. — I am indebted to my friend J. A. McNiel for 

 the opportunity of describing this beautiful species. He has 

 for several years devoted much time to collecting the shells of 

 this genus, with marked success, having, by his liberality, fur- 

 nished the many forms from this State, described in this Journal, 

 with others yet to be characterized. 



This shell resembles nearly An. pallida., glandulosa and 

 irisans of Anthony, but differs from either in color, in being 

 more decidedly biangulate, in the prominent carina, the arborei- 

 form markings, different position of lines of periodic growth, 

 and in general appearance. It is altogether our most beautiful 

 species. 



