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. 
Buomphalus (Phanerotinus) laxus Hall. 
Plate vi, fig.3. 
Euomphalus lawus Hall, 1861. Descriptions of New Species of Fossils, ete., p. 26. 
1862. Fifteenth Ann. Rep. N. Y. State Cab. Nat. Hist., p. 54, 
pl. vi, fig. 2. 
(Eceuliomphalus?) lavus Hall, 1876. Pal. N. Y., lustrations of Devonian 
Fossils, Gasteropoda, pl. xvi, figs. 16-18. 
comes Hall, 1876. TIbid., pl. xvi, figs. 8, 9. 
(Phanerotinus) lacus Hall, 1879. Pal. N. Y., vol. v, pt. 2, p. 60, pl. 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 disjoitied volutions, broadly umbilicated under-side, gradual 
expansion from the apex, circular section, and concentric surface striz, 
the species is identical with Z. lacus. 
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 Z. lavus that corresponds closely to 
Evomphalus (S.) Hecale Hall, (Pal. N. Y., vol. v, pt. 2, p. 59, pl. 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. 
