286 PALEONTOLOGY OF THE EUREKA DISTRICT. 



view. The character of the siphuncle in its passage between the septa has 

 not been observed. 



The test is rather strong, and is vertically striated on the interior as 

 shown- in the cast, the strise being exceedingly fine. The exterior surface 

 has been so injured by the mineralization of the test, that its characters are 

 not determinable. 



A slight carina is preserved on the cast of the dorsal surface. It does 

 not appear to have any connection with the siphuncle or areola surround- 

 ing it. 



Orthoceras clinocameratum Wiuchell (Amer. Jour. Sci., vol. xxxiii, p. 356, 

 1862) is the only American species that appears to correspond to this. 

 With the description to decide from, it does not appear that the Michigan 

 and Nevada shells belong to one species. 



Formation and locality. Lower portion of Lower Carboniferous lime- 

 stone in canon directly south of a small conical hill on east side of Secret- 

 canon-road Canon, Eureka District, Nevada. 



Orthoceras, sp. f 



A small species, with fine vertical annulations, is associated with 0. 

 Eurekensis. It appears to be slightly curved, and to have its cone enlarg- 

 ing gradually and uniformly. 



PCECILOPODA. 



Genus GRIFFITHIDES Portlock. 



Griffithides Portlocki M. & W. 



Plate xxiv, figs. 4, 4fl, 6. 



Phillipsia (Griffithides) Portlocki Meek & Worth en, 1865. Proc. Acad. Nat. Sci. Philad., 

 vol. xvii, p. 268. Ibid., 1873. Geol. Surv. Illinois, vol. v, p. 625, pi. xix, 

 . fig- 6. 



The detailed and elaborate description given of this species by its 

 authors provides the means for a close comparison between it and the Ne- 

 vada specimens. 



