FOSSILS OF THE (JAMBEIAN. 



13 



The species is well represented, and appears to be characteristic of the 

 Upper portion of the Cambrian and the lower horizon of the Silurian, 

 Pogonip Group. It occurs in the Secret Canon shale of the Cambrian on the 

 eastern side of the canon directly east of Ruby Hill; in the limestone of 

 the Pogonip Group northeast of Adams Hill; on the ridge southeast of the 

 Jackson mine; on the southwest spur of Wpod Cone, and southeast of the 

 Hamburg mine, Eureka District, Nevada. 



Lingulepis f minuta H. & W. 



Lingulepis f minuta Hall & Whitfield, 1877. Geol. Expl., Fortieth Parallel, vol. iv, 

 p. 206, pi. i, figs. 3, 4. 



This species has nearly the same vertical range and geographical 

 distribution as Lingulepis Mcera, usually occurring in the same localities. 

 The type specimens were obtained in the Eureka District by the members 

 of the Fortieth Parallel Geological Survey. 



Genus LINGULA Bruguiere. 



Lingula f manticula White. 



Plates is, fig 3, and xi, fig. 2. 



Lingula 1 manticula White, 1874. Expl. and Surv. West 100th Merid.j Prelim. 

 Eep. Pal., p. 9. Ibid., vol. iv, pt. 1, p. 52, pi. iii, figs. 2, 6, 1875. 



The range of variation among the specimens we have referred to this 

 species is greater than exists between them and our conception of L. f 

 manticula, as obtained from the description and illustrations given by 

 Dr. White, and without a direct comparison with the type specimens to 

 determine any specific differences, if they exist, we consider them as one 

 species. As none of the examples show the internal characters of the shell, 

 the doubtful character of the generic reference remains unchanged. 



The type specimens were collected in the Schell Creek Range of Ne- 

 vada, at an horizon in the Silurian, equivalent probably, to the horizon at 

 which the species occurs in the Pogonip Group. 



