NO. 3 . CAMBRIAN TRILOBITES 249 



PAGE 



Crepicephalus upis Walcott 218 



Fig. 4. (X2.) Cranidium with broken front border restored from 



associated specimens. U. S. National Museum, Catalogue 



No. 61695. 

 4a. (X2.) Under side of associated free cheek. U. S. National 



Museum, Catalogue No. 61696. 

 4b. (X2.) Pygidium associated with fig. i. U. S. National 



Museum, Catalogue No. 61697. 

 4c. (X2.) Under side of an associated pygidium. U. S. National 



Museum, Catalogue No. 61698. 

 4d. (Natural size.) Fragment of weathered shaly limestone on 



which several cranidia occur and the pygidium represented 



by fig. 4b. 



The specimens represented by figs. 4, 4a-d are from locality 

 150b, Upper Cambrian : Gallatin limestone ; at head of White 

 Creek, Lewis and Qark National Forest. Montana. 



