FOSSILS OF THE CAMBRIAN. 



57 



Ptychoparia granulosus H. & W. 



CrepicepJialus (Loganellus) granulosus Hall & Wbitfield, 1877. 

 Par., vol. iv, p. 214, pi. ii, figs. 2, 3. 



Geol. Expl. Fortieth 



Types from the Eureka District. The species occurs at the summit of 

 the Secret Canon shale, across the canon from the dump of the Richmond 

 shaft, Ruby Hill, and in the lower part of the Pogonip Group, southeast 

 of the Jackson mine, Eureka District, Nevada. 



Ptychoparia Hague! H. & \V. 



Crepicephalus (Loganellus) Haguei Hall & Whitfield, 1877. Geol. Expl. Fortieth Par., 

 vol. iv, p. 210, pi. ii, figs. 14, 15. 



Types from Pogonip Mountain, White Pine District, Nevada. 



In the Eureka District this species has a range nearly equal to that of 

 P. Gallatinensis, but, as yet known, it does not extend down below the sum- 

 mit of the Secret Canon shale. At that horizon it occurs on the eastern 

 side of Secret Canon and the opposite side of the canon from the dump of 

 the Richmond shaft, Ruby Hill, and at the summit of the Hamburg shale 

 east of the Hamburg mine, and also in the lower part of the Pogonip 

 Group at the same locality. 



Ptychoparia nitidus H. & W. 



Crepicephalus (Loganellus) nitidus Hall & Whitfield, 1877. Geol. Expl. Fortieth Par., 



vol. iv, p. 212, pi. ii, figs. 8-10. 

 Crepicephalus (Loganellus} simulator Hall & Whitfield, 1877. Geol. Expl. Fortieth 



Par., vol. iv, p. 218, pi. ii, figs. 16-18. 



When studying a large series of specimens of Ptychoparia nitidus it was 

 observed that the head and pygidium varied in size, and that there were no 

 differences between the larger sized specimens of the head and the type of 

 Crepicephalus (Z/) simulator. 



The types of the two species described by Messrs. Hall and Whitfield 

 were collected in the Eureka District by the geologists of the Fortieth Par- 

 allel Exploring Expedition, and the species is quite abundant in strata near 

 the summit of the Cambrian series. 



