CAMBRIAN FOSSILS. 457 



in the State of Georgia. From the occurrence of large numbers of entire 

 specimens on nodules in the Coosa Valley, in Alabama, a few miles west of 

 the Georgia State line, it is thought probable that the specimen referred to 

 came from that locality. A comparison of a series of specimens from the 

 Coosa Valley locality with the Gallatin Rang'e specimens shows a very 

 close resemblance between them. The Alabama specimens have two 

 marked variations in the frontal limb and border; in one the limb is gently 

 rounded to a marked groove that separates it from a strong rounded frontal 

 rim; in the other, the groove in the frontal rim curves backward from each 

 side toward the glabella so as to indent the frontal limb. As a result of the 

 comparison, it is found that the range of variation among the individuals ol 

 P. antiquata includes not only the Gallatin species but also the varieties of it. 

 Formation and locality: Middle Cambrian, Flathead formation, Crow- 

 foot section, Gallatin Range; bluff on south side of Pebble Creek, north of 

 saddle to Soda Butte Creek; on ridge near Crowfoot section, Gallatin 

 Range, Yellowstone National Park. East of Dead Indian Creek, Absaroka 

 Range, Wyoming'. . 



Ptychoparia (E.) affinis Walcott. 

 PI. LXV, fig. S. 



Ptychoparia (&) affinis Walcott, 1884: Moil. U. S. Geol. Surv., Vol. VIII, p. 54, PI. 

 X, fig. 12. 



With the material at hand it is impossible to make a positive identifi- 

 cation with the type species from the Upper Cambrian of the Eureka 

 district, Nevada. There is, however, a striking similarity in the only por- 

 tions we have for comparison, the center of the head. 



A similar species occurs in the Cambrian beds of Honey Creek, Bur- 

 nett County, Texas, and it is probable that the specimens from the three 

 widely separated localities are identical. 



Formation and locality: Middle Cambrian, Gallatin limestone, Liv- 

 ingston section, at head of Davis Creek, Snowy Range, Montana. 



