CAMBRIAN FOSSILS FROM PIOCHE MOUNTAINS 297 



size. Walcott originally figured the head with three pairs of glabellar 

 furrows, but it was later shown that four were present. The writer 

 found two heads somewhat resembling the type. They differ from 

 it mostly in the presence of a frontal margin, which is well developed 

 in the antero-lateral portion. There are four pairs of well-defined 

 glabellar furrows ; the posterior pair points obliquely backward ; the 

 second pair points almost directly across; the third and fourth pairs 

 point obliquely forward. The glabella is broadly expanded in front 

 of the eyes. The postero-lateral hmbs are not preserved. The two 

 heads were collected at the Half Moon Mine. The writer tentatively 

 refers them to this species. 



Location : Himon Mine, Abe Lincoln Mine, Half Moon Mine. 



Bathyuriscus productus, H. & W. 



(Plate II, Figs. 3, 3a, 3&) 



Ogygia prodiicta, Hall & Whitefield, 1887: GeoloiJical Exploration oj the 

 Fortieth Parallel, Vol. IV, p. 244, Plate 2. 



Bathyuriscus producta, Walcott, 1886: Bulletin No. jo, U. S. Geological 

 Survey, p. 217, Plate 30. 



This species occurs in great abundance; its remains are largely 

 fragmentary, the pygidia being the most common. 

 Location : Himon Mine and Abe Lincoln Mine. 



GENUS PTYCHORPARU. Corda 

 Ptychoparia, Corda, 1847: Prodram. Man. hohm. Trilobiten, p. 141. 

 Equals Conocephalus, Zenker, 1833. 

 Equals Conocephalus, Barrande, 1852. 



Ptychorparia piochensis, Walcott 



(Plate II, Figs. 4, 4a, 4b, 4c) 

 Ptychoparia piochensis, Walcott, 1886: Bulletin No 30, U. S. Geological 

 Survey, p. 201, Plate 28. 



This is a very characteristic form ; it occurs throughout the entire 

 shaly stratum, and usually is abundantly represented. The heads 

 are most commonly preserved, but almost perfect fossils are frequently 

 found. In all of the specimens figured by Mr. Walcott the frontal 

 rim appears to bend downward. This is probably a fault of the 

 drawing, as not a single form in the writer's collection shows this 

 condition. The frontal margin turns somewhat abruptly upward 

 into the frontal rim (Fig. 4a). 



