124 PALEONTOLOGY OF THE EUREKA DISTRICT. 



Chonetes deflecta Hall. 

 Plate ii, figs. 8, 8 a, b. 



Chonetes deflecta Hall, 1857. Tenth Ann. Rep. N. T. State Cab. Nat. Hist., p. 149. 

 gibbosa Hall, 1857. Ibid., p. 145. 

 deflecta Hall, 1867. Pal. N. Y., vol. iv, p. 126, pi. xxi, figs. 7a-g, Sa-c. 



The shells referred to this species are from the Upper and Lower De- 

 vonian beds, and in size, general form, convexity and surface markings are 

 specifically identical with the examples of the species from the Hamilton 

 Group of New York. There is considerable difference in the height and 

 widfft of different shells, and also in the strength of the radiating surface 

 striae. In the latter variation Chonetes acutiradiata Hall is directly connected 

 with C. deflecta, as expressed in its more transverse forms. Some of the 

 more coarsely striated examples approach C. mucronata, but not sufficiently 

 so to be identified with that species. 



Its vertical range is from the Lower Devonian Upper Helderberg 

 Group of New York, to the Upper Devonian =zChemung Group of New 

 York 



Formation and localities. Lower horizon of the Devonian limestone, 

 Comb's Peak, west slope of County Peak, and lower beds at Lone Mount- 

 ain, 18 miles northwest of Eureka, Upper Devonian of Rescue Hill, Eureka 

 District, Nevada. 



Chonetes mucrouata Hall? 



Strophomena mucronata Hall, 1843. Geol. Rep. Fourth District New York, p 181 and p. 



180, fig. 3. 



Chonetes laticosta Hall, 1857. Tenth Ann. Rep. N. Y. State Cab. Nat. Hist, p. 119. 

 mucronata Hall, 1867. Pal. N. Y., vol. iv, p. 124, pis. xx, xxi. 

 Nicholson, 1873. Pal. Prov. Ontario, p. 74. 



Professor Hall gave the specific designation C. laticosta to a small, gib- 

 bous, coarsely striated shell from the Upper Helderberg and Hamilton 

 Groups of New Yi.rk, which he subsequently considered as a variety of 

 Chonetes mucronatc. With this form the Nevada specimens are identified, as 

 none of the larger, more finely striated examples are yet known from the 

 Rocky Mountain area. 



