222 PALEONTOLOGY OF THE EUEEKA DJSTEICT. 



Retzia Marcyi Shumard is probably a finely-ribbed variety of R. radialis, 

 and a large series of specimens may bring R. vera and R. Verneuiliana of 

 the Lower Carboniferous limestone of Iowa into the same group as varieties. 



As now known in Central Nevada, R. radialis ranges from the Upper 

 Devonian through the Lower into the Upper Carboniferous limestone, a 

 horizon equivalent to that of the Upper Coal Measures, where it is found 

 in Nebraska, Illinois, etc. Its great geographic range has already been 

 noticed in speaking of its occurrence in China, India, the Ural Mountains, 

 England, and Western America. 



Genus ATHYEIS McCoy. 



Athyris hirsuta Hall. 

 Plate xviii, fig. 5. 



Spirigera (Athyris) hirsuta Hall 1857. 15 Trans. Albany Institute, vol. iv, p. 8. 

 Athyris sublamellosa Hall, 1858. Geol. Surv. Iowa, vol. i, pt. 2, p. 702, pi. xxvii, fig. 



1 a-c. Idem., Derby, 1874. Bull. Cornell University, vol. i, No. 2, p. 10, 



pi. ii, figs. 9-12; pi. iii, figs. 15, 21, 29; pi. vi, fig. 16; pi. ix, figs. 5, 6. 

 Athyris hirsuta Whitfield, 1882. Bull. Ainer. Mus. Nat. Hist., vol. i, p. 49, pi. vi, figs. 



18-21. 



Compare Athyris Royssii. See Brit. Foss. Brach. Davidson, vol. ii, p. 84. 



There is so little difference between the examples of this species from 

 Nevada and those from the Chester limestone of Illinois, that the lithologic 

 features of the matrix alone distinguishes them. It is not improbable 

 tiiat this species is founded on a small variety of Athyris Royssii, and Mr. 

 Meek has placed it as a doubtful synonym (Geol. Expl. Fortieth Par., vol. 

 iv, p. 82). 



Formation and locality. Lower portion of the Carboniferous Group, 

 Diamond Peak, in the Eureka District, and at Coal Hill, Pancake Range, 

 Nevada. 



16 The paper describing the Spergen Hill fossils \vas printed aud copies distributed in 1857 in 

 advance of the publication of Volume IV of the Albany Institute Transactions, which bears date 



1858-1864. 



