242 PALEONTOLOGY OF THE EUKEKA DISTRICT. 



Dimensions: height, 6 mm ; width, 7 mm ; convexity or depth of right 

 valve, 2 mm . 



This small species is more closely allied in external form to Nucula ? 

 levata Hall (Pal. N. Y., vol. i, p. 150, pi. xxxiv, figs. 1 a-i, 1847), of the 

 Trenton limestone of New York than to any Carboniferous species that 

 I am acquainted with. 



Formation and locality. Lower portion of Lower Carboniferous lime- 

 stone in canon directly south of conical hill on east side of Secret-canon- 

 road Canon, Eureka District, Nevada. 



Genus SOLENOMYA Lamarck. 



Solenomya curta, n. sp. 

 Plate xxii, figs. 6, 11. 



Outline transversely elliptical or oblong-oval, moderately convex. 

 Hinge-line about one-half the length of the shell ; beak depressed, situated 

 at the anterior third of the shell. 



Surface with narrow undulations of growth, crossed by nearly obso- 

 lete, radiating, flat plications, with finer striae between. 



Interior characters unknown. 



Dimensions: height, 2.25 cm ; width, 3.75 cm ; convexity or depth of left 

 valve, .5 cm . A smaller, more elongate right valve has a height of 1.5 cm , and 

 a width of 3 cm . With but one specimen of the latter to study it is referred 

 to this species somewhat provisionally, as there is no series of forms unit- 

 ing it with the former. 



I know of no species with which this can be directly compared, its 

 shorter, higher form distinguishing it from described species. 



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. 



