FOSSILS OF THE CABBONIFEROUS. 



245 



Grammysia arcuata Conrad (Sp.) 

 Plate xx, fig. 5. 



Posidonia f arcuata Conrad, 1841. Ann. Eep. Geol. Surv. New York, p. 53. 

 Grammysia arcuata Hall, 1870. Prelim. Notice Lam. Shells, p. 56. 



(Leptodomus f) arcuata Hall, 1883. Pal. N. Y., vol. v, pt. 1 ; Plates and 

 Explanations, pi. Ixi, figs. 1-9. 



Although this species is confined to the Hamilton Group of New York 

 and Virginia, as far as heretofore known, we are unable to separate the Car- 

 boniferous shell from it on good specific grounds. Its occurrence at this 

 locality and horizon is not surprising, as we have in the Devonian, and also 

 at this same locality, examples of as great a range of supposed limited 

 species, e. g., Pleurotomaria nodomarginata, Schizodus cuneatus, etc. 



Formation and locality. Lower portion of the Carboniferous Group on 

 the east slope of a small conical hill on the east side of Secret- canon-road 

 Cafion, Eureka District, Nevada. 



Genus EDMONDIA De Koninck. 



Edmondia Medon, n. sp. 

 Plate xxiii, fig. 6. 



Shell transversely subelliptical, moderately convex, equivalve. Hinge- 

 line slightly arcuate ; beaks depressed, situated on the anterior third of the 

 shell. 



Surface marked by concentric lines and undulations of growth. 



Interior characters unknown. 



Dimensions : height, 1 5 cm ; width, 2.5 cm ; convexity of single valve, 0.5 cm . 



The specimen illustrated is the only well-preserved one we have of this 

 species. In some respects it approaches E. Burlingtonensis W. and W. 

 (See Pal. N. Y., vol. v, pt. 1 ; Plates and Explanations, pi. Ixiv, figs. 19-29, 

 1883), of the Burlington limestone of Iowa, and the Chemung Group of 

 New York, differing in its more elliptical form and depressed beak. 



Formation and locality. Lower portion of Lower Carboniferous lime- 

 stone on east slope of a small conical hill on the east side of Secret-canon- 

 road Canon, Eureka District, Nevada. 



