FOSSILS OF THE DEVONIAN. 107 
essential particulars. It is a rare species, both in the Hamilton Group of 
New York and the lower horizon of the Devonian formation at Lone Mount- 
ain, 18 miles northwest of Eureka, Nevada. 
Dimensions: length, 17™"; greatest breadth, 12™. 
Lingula Ligea Hall. 
Plate ii, fig. 2. 
Lingula ligea Hall, 1860. Thirteenth Ann. Rep. N. Y. State Cab. Nat. Hist., p. 76. 
Ibid., 1867. Pal. N. Y., vol. iv, p. 7, pl. i, fig. 2a, b; pl. ii, fig. 8. 
This pretty and symmetrical little shell is represented by one specimen 
that in external appearance is identical with specimens of L. Ligea now before 
me, from the Hamilton Group of New York. 
In a layer of limestone, about 59 feet above that containing the above- 
mentioned shell, a number of examples of a form that may be only a varia- 
tion of L. Ligea were collected. In as close a genus as Lingula, however, 
this variation is unusual, and a varietal distinction is made. 
Lingula Ligea var. Nevadensis, n. var. 
Plate ii, fig. 3. 
Shell below the average size of L. Ligea, and with more rounded sides 
and pointed beaks than that species. 
Surface marked by fine concentric strize of growth. 
The interior of the ventral valve shows the path of advance of two 
central muscular scars, and also a lateral scar on each side. The impres- 
sions of the scar are too faint to be of any service in determining their 
character or number. 
Formation and locality of this and the preceding species, Upper Devo- 
nian of Rescue Hill, Kureka District, Nevada. 
A species undistinguishable from this occurs in the Lower Devonian of 
the south slope of Sentinel Mountain, Eureka District, Nevada. 
