186 PALEONTOLOGY OF THE EUREKA DISTRICT. 



the periphery of the outer volution, and in another it is still more depressed, 

 the umbilicus being nearly flat. 



Formation and localities. Lower horizon of the Devonian limestone, 

 Comb's Peak, and Atrypa Peak Ridge, Eureka District, Nevada. 



Euomphaltis (Phanerotinus) laxus Hall. 

 Plate vi, fig.3. 



Euomphalm laxm Hall, 18(51. Descriptions of New Species of Fossils, etc., p. 26. 



1862. Fifteenth Ann. Eep. N. Y. State Cab. Nat, Hist., p. 54, 



pi. vi, fig. 2. 

 (Ecculiomphalus ? ) laxus Hall, 1876. Pal. N. Y., Illustrations of Devonian 



Fossils, Gasteropoda, pi. xvi, figs. 16-18. 

 comes Hall, 1876. /&#., pi. xvi, figs. 8, 9. 

 (Phanerotinus} laxus Hall, 1879. Pal. N. Y., vol. v, pt. 2, p. 60, pi. xvi, 



figs. 8, 9, 16-18. 



Compare Phanerotinus paradoxus Winchell, 1863. Proc. Acad. Nat. Sci. 

 Philad., vol. xv, p. 21. 



The representatives of this species from the Upper Devonian are 

 smaller than the average-sized specimens from the Hamilton Group of New 

 York. In the disjoined volutions, broadly umbilicated under-side, gradual 

 expansion from the apex, circular section, and concentric surface striae, 

 the species is identical with E. laxus. 



It seems somewhat improbable that a form of this character should 

 range from the Upper Helderberg and Hamilton Groups of New York up 

 to the summit of the Devonian in Nevada, but with the large number of 

 species which we know are common to the two localities and the identity in 

 form between the shells of this species from each locality, there appears no 

 other way than to place them under the same specific name. 



There is a species associated with E. laxus that corresponds closely to 

 Euomphalus (S.) Hecale Hall, (Pal. N. Y., vol. v, pt. 2, p. 59, pi. xvi, figs. 

 10-14), from the Chemung Group of New York and Pennsylvania, the 

 difference being in the more rapid expansion of the outer volution. The 

 specimens at hand are too imperfect for specific description. 



Formation and locality. Upper Devonian ; The Gate, northwest of 

 Eureka, Nevada. 



