46 PALEONTOLOGY OF THE EUREKA DISTRICT. 
rows; occipital furrow distinctly defined; occipital ring strong, with a small _ 
spine on the center of the posterior portion; dorsal furrows well defined 
along the sides of the glabella; fixed cheeks of medium width, palpebral 
lobes unknown; an ocular (?) ridge crosses the anterior portion of the 
right fixed cheek, so as to indicate a moderate sized eyelobe between it and 
the postero-lateral limb; frontal limb as a narrow rim; postero-lateral limbs 
rather narrow, extended and marked by a strong furrow within the poste- 
rior margin. 
Surface finely punctate. 
This species and the preceding are closely related, judging from the 
parts which we have for comparison. It is hoped that in some more favor 
able locality entire specimens may be obtained of these and the many other 
species known only by fragments, so that the generic characters can be 
determined with greater certainty and more positive specific references 
made. 
Formation and localities —Cambrian. Prospect Mountain limestone at 
base of Secret Canon shale, in New York Canon, and also in a small expos- 
ure of Cambrian limestone on the west side of the Mahogany Hills, in 
Antelope Valley, Eureka District, Nevada. 
Genus PTYCHOPARIA Corda.§ 
Ptychoparia (?) Prospectensis, n. sp. 
Plate ix, fig. 20. 
The general outline of the head is moderately convex, semicircular, 
the width being about twice the length. 
The glabella is subconical, truncate in front and marked by three pairs 
of short, slightly impressed glabellar furrows; occipital ring distinctly de- 
fined by a narrow, lightly impressed occipital furrow; fixed cheeks broad, 
of equal elevation with the glabella, and extending beyond it anteriorly, 
the space between them on the broad frontal limb being taken by a small 
5The reason for using the generic term Ptychoparia rather than Crepicephalus, as used by 
Messrs. Hall and Whitfield in the Paleontology of the Fortieth Parallel Exploring Expedition, is given 
in a bulletin of the Geological Survey now ready for the press, entitled a ‘‘ Review of the Fauna of the 
St. John Formation.” The relations of the genera Conocoryphe, Ptychoparia, Crepicephalus, Soleno- 
pleura, Liostracus, and Conocephalites are mentioned.—C. D. W. 
