FOSSILS OF THE CABBONIFEKOUS. 



267 



The most striking difference is the greater strength of the postero-lateral 

 spine of the free cheek in the Nevada form. This, however, is scarcely a 

 specific variation, and the other variations are not of specific value. 



Judging from the external features of the head, this species may be re- 

 ferred to the genus Griffithides. In the cast traces of two anterior pairs of 

 glabellar furrows appear, but these are not seen on the outer surface of the 

 shell. Again, the form of the glabella is that of the typical forms of 

 Griffithides. 



Of the nineteen species referred to the genus Phillipsia, from American 

 Paleozoic strata, I do not know of one that would not admit of question. 

 Eight are founded on specimens of the pygidiuin alone, and the generic 

 reference is consequently questionable. One species, Phillipsia Lodiensis 

 Meek (Pal. Ohio, vol. ii, p. 323, plate xviii, fig. 3), is, as suggested by Mr. 

 Meek, referable to the genus Proetus or a subgenus of Proetus, and in this 

 same list may be included the two Devonian species (ante p. 211 and Pal. 

 N. Y., Illustrations of Devonian Fossils, plate xxi, fig. 29, P. Icevis). Of 

 the species left, none appear to possess the typical features of Phillipsia, 

 but on the contrary are more nearly allied to Griffithides. 



Formation and locality. Lower portion of Lower Carboniferous lime- 

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

 cafion-road Canon, Eureka District, Nevada. 



