120 PALEONTOLOGY OF THE EUKEKA DISTRICT. 



Strophodonta inequiradiata Hall. 

 Plate 11, figs. 11, 11 a. 



Strophomena (Strophodonta) inequiradiata Hall, 1857. Tenth Ann. Eep. N. Y. State 



Cab. Nat. Hist., p. 113. 

 incequistriata Billings, 1861. Can. Jour., vol. vi, p. 338, fig. 113. Ibid., 



Geology of Canada, 1863, p. 367, fig. 375. 



Strophodonta inequiradiata Hall, 1867. Pal. N. Y., vol. iv, p. 87, pis. xi, xii, xiii. 

 Strophomena inequiradiata Billings, 1874. Pal. Foss., vol. ii, pt. 1, p. 24. 



This species is closely allied to S. Patersoni, as is shown by a series of 

 specimens from the Upper Helderberg Group of New York. The Nevada 

 specimens, however, represent the well-marked characters of each species, 

 so that there is little danger of mistaking one for the other. They occur 

 at the same stratigraphic horizon, but in localities 15 miles distant from 

 each other. 



Formation and locality. Lower horizon of the Devonian limestone, 

 Comb's Peak, Eureka District, Nevada. 



Strophodonta perplana Conrad (Sp.). 



Plate xiii, fig. 11. 



Strophomena perplana Conrad, 1842. Jour. Acad. Nat. Sci. Philad., vol. viii, p. 257 r 

 pi. xiv, fig. 11. 



pluristriata Conrad, idem., p. 259. 



delthyris Conrad, idem., p. 258. 



crenistria Hall, 1843. Rep. Fourth Geol. District New York, p. 171. 



nervosa Hall, idem., p. 266, fig. 1. 

 Strophodonta fragilis Hall, 1857. Tenth Ann. Eep. N. Y. State Cab. Nat. Hist, p. 143. 



fragilis Hall, 1858. Geol. Eep. Iowa, vol. i, pt. 2, p. 496, pi. iii, figs. 6 a-c. 

 Strophomena perplana Billings, 1861. Can. Jour., vol. vi, p. 343. 

 Strophodonta perplana Hall, 1867. Pal. N. Y., vol. iv, pp. 92, 98, and 113, pis. xi, xiii r 



xvii, and xix. 

 Strophomena perplana Nicholson, 1873. Pal. Prov. Ontario, p. 64. 



This well-marked species ranges from the lower horizon to nearly the 

 summit of the Devonian limestone. It is represented by a number of speci- 

 mens which, although somewhat imperfect, exhibit the general outline, slight 

 convexity, and fine surface striae of the ventral valve, as also the large flabel- 

 liforni divaricator muscular impressions. In New York it is found to pass 



