FOSSILS OF THE CAMBRIAN, yt 
Ptychoparia (Euloma ?) dissimilis, n. sp. 
Plate ix, fig. 28. 
Glabella prominent, strongly convex, the anterior lobe curving down- 
ward and under to the frontal margin; length and width at the base equal; 
marked by two pairs of glabellar furrows extending obliquely inward, the 
posterior pair nearly cutting off the triangular-shaped posterior lobes; occip- 
ital ring broad at the center, narrowing laterally; occipital furrows strongly 
impressed, as are the dorsal furrows along the sides of the central and pos- 
terior portions of the glabella; fixed cheeks very narrow; palpebral lobes 
large, moderately elongate, slightly sinuous, with a strong groove within 
the margin; frontal lobe a narrow rounded rim; postero-lateral limbs un- 
known. 
This species is known only by the parts mentioned. It is allied to 
Ptychoparia Eos Hall, and a somewhat similar form has been described as 
Menocephalus Sedgwicki Billings. They appear to form a small group of 
the Conocephalide, the limits of which have not been defined. The refer- 
ence to the genus Menocephalus is of doubtful propriety, since, up to the 
present time, the fragment referred to as the type by Owen has never again 
been even generically or specifically recognized in all the great collections 
from the Potsdam sandstone of the Wisconsin and Minnesota, and it appears 
to be practically impossible to identify it. The two species referred to the 
genus by Billings, Palzeozoic Fossils, vol. i, p. 407, and Geology of Canada, 
p. 237, also appear to belong to two distinct genera. 
Formation and locality—Cambrian. Secret Canon shale of the Prospect 
Mountain Group, New York Canon, Eureka District, Nevada. 
Ptychoparia occidentalis, n. sp. 
Plate x, fig. 5. 
Head within the facial sutures, exclusive of the postero-lateral limbs, 
quadrangular in form; glabella subconical, the sides slightly converging 
towards the rounded front; surface uniformly convex and marked by three 
pairs of moderately oblique glabellar furrows, the two posterior pairs of 
