194 PALEONTOLOGY OF THE EUREKA DISTRICT. 
the transversely ovate aperture; a narrow dorsal carina is distinctly shown 
on the cast, and, very obscurely, traces of transverse striz. 
This is the largest of the several species occurring in the Devonian 
limestone of Nevada. Its length is 48""; transverse section midway of the 
outer volution 30", near the aperture 45™™. 
Formation and locality—Lower horizon of tl¥e Devonian limestone, 
Comb’s Peak, Eureka District, Nevada. 
Bellerophon lyra Hall (Pal. N. Y., vol. v, pt. 2, p. 113, pl. xxiii, figs. 1, 17-20). 
A single specimen that corresponds in form and surface markings to 
this species occurs in the Devonian limestone on the eastern side of the 
District. It has been slightly worn by exposure to the weather, but not so 
much as to remove the fine, undulating, revolving striz. 
Bellerophon Leda Hall (Pal. N. Y., vol. v, pt. 2, p. 110, pl. xxiii, figs. 2-16). 
The Nevada form is a little less flattened on the dorsum, and the dorsal 
carina is more prominent, as are the revolving striz; this, however, is rather 
the result of a difference in the conditions of preservation than of absolute 
differences in the shells; the New York specimens usually occurring in the 
argillaceous shales or shaly limestones have suffered by compression. 
Bellerophon Mera Hall? (Pal. N. Y., vol. v, pt. 2, p. 119, pl. xxv, figs. 9-14; p!. xxvi, 
figs. 19-24). 
A fragment from the higher beds south of The Gate has a thick test 
thickly studded with rows of pustules’ in a manner similar to that of B. 
Mera of the Chemung Group of the State of New York. The general 
form of the volutions and dorsal carina also adds to the strength of the 
comparison 
Bellerophon Pelops Hall? (Pal. N. Y., vol. v, pt. 2, p. 99, pl. xxii, figs. 7-13). 
Associated with B. Leda, there is a form that corresponds to one of the 
varieties of this species from the Upper Helderberg limestone of the State 
of New York. The transverse strie of the surface of the body volution 
bending backward towards the dorsal carina and the expanded aperture 
show in the Nevada specimen. 
