216 PALEONTOLOGY OF THE EUltEKA DIST1UOT. 



Formation and localities. Lower portion of the Carboniferous Group, 

 summit of Diamond Peak, and in the low hills at the mouth of Hayes' 

 Canon, Eureka District, Nevada. 



Spirifera Leidyi N. and P. 

 Plate xviii, figs. 4, 4 a. 



Spirifera Leidyi, Norwood & Pratten, 1855. Jour. Acacl. Nat. Sci. Philad., 2d series, 



vol. iii, p. 72, pi. ix, figs. 2 a-c. 



Spirifera bifurcatus, Hall, 1857. Trans. Albany Institute, vol. iv, p. 8. 

 Spirifera bifurcata, Whitfield, 1882. Bull. Amur. Mas. Nat. Hist,, vol. i, No. 3, p. 47, 



pi. vi, figs. 13-15. In the remarks accompanying the latter reference, Mr. 



Whitfield considers S. bifurcata as a synonym of 8. Leidyi. 



The only mention of the occurrence of this species west of the Missis- 

 sippi basin is found in a list of Carboniferous fossils from the Oqnirrh Range, 

 Utah, given in the second volume of the Geological Exploration of the For- 

 tieth Parallel, page 447. 



There appears to be little doubt of the specific identity of the Nevada 

 shell with that from the typical locality in the Chester limestone of Illinois. 



Formation and localities. Lower portion of the Carboniferous Group, 

 Richmond Mountain, and on the low hills south of the mouth of Hayes' 

 Canon, Eureka District, Nevada. 



Spirifera aniiectans, u. sp. 

 Plate xviii, figs. 7, 7 a. 



Shell below the medium size, somewhat inflated, length and breadth as 

 3 to 4, respectively ; anterior and lateral margins forming rather more than 

 a semicircle before uniting with the cardinal line, which is about three-fifths 

 the breadth of the shell. 



Ventral valve with a strongly defined mesial sinus extending to the 

 extremity of the rather prominent, incurved beak ; the bottom of the sinus 

 is but slightly rounded and with a scarcely perceptible elevated line along 

 the center; the sinus is bordered by a rounded rib, outside of which, on 

 each side, there are four ribs, the outer almost obsolete on the smooth 



