56 PALEONTOLOGY OF THE EUEEKA DISTRICT. 



and at various horizons between the two in New York, Secret, and Sierra 

 Canons, and on the Hamburg Ridge. In the Black Hills it occurs at 

 about the horizon of the upper portion of the Prospect Mountain Group of 

 the Eureka District, Nevada. 



In a report on the Cambrian fauna of the United States, now in course 

 of preparation, the types of the various species given in the synonymy of 

 Ptychop&ria Oweni will be illustrated 



Ptychoparia Anytus H. & W. 

 Plate ix, fig. 26. 



Crepicephahts (LocjaneUiis] nnytus Hall & Whitfield, 1877. Geol. Expl. Fortieth Par., 

 vol. iv, p 219, pi. ii, figs. 19-21. 



Compare Crepicephalus=Plychoparia planus Whitfield, 1877. Geology and Resources 

 of the Black Hills of Dakota, p. 341, pi. ii, figs. 21-24. Also Crepicephalus 

 (L.) = Ptychoparia Montanensin Whitfield, 1876. Rep. Recon. Carroll, 

 Montana, to Yellowstone Kat. Park, Lndlow, p. 141, pi. i, figs. 1, 2. 



The specimen illustrated by fig 26 of plate ix, differs from the type of 

 P. Anytus in having a somewhat narrower, more quadrilateral glabella, 

 and also a thicker anterior rim to the head, but on comparing several spe- 

 cimens with the typical specimens from Schell Creek, Nevada, these varia- 

 tions are seen in each series, and no satisfactory differences remain upon 

 which to base a distinct species. The figure given by Messrs. Hall and 

 Whitfield shows a larger, broader, and more conical glabella in proportion 

 to the head than that of fig. 26, plate ix, of this report, the two figures in 

 the two reports giving the range of variation in the head as far as known. 



On comparing the type of P. planus Whitfield, with a head of P. Anytus, 

 broken just as the type of P. planus is, there does not appear to be the 

 slightest difference between the two. We labor, however, under the dis- 

 advantage of comparing with a cast of a fragment of the head as the origi- 

 nal type, and cannot decide positively until more and better material is 

 collected from the original locality. 



P. Montancnsis is a closely allied species of which we have not seen 

 the original type. 



Formation and locality. Cambrian. In the upper beds of the Secret 

 Canon shale, on the east side of New York and Secret Canons, Eureka 

 District, Nevada. 



