NO. 5 CAMBRIAN TRILOBITES 425 



Dolichometopus ? bessus Walcott 362 



Fig. 3. (X 2.5.) Broken dorsal shield, showing characters of species. 

 U. S. National Museum, Catalogue No. 62699. 

 3a. (X2.) Pygidium. U. S. National Museum, Catalogue No. 



62700. 

 3&. (X2.) Cephalon and hypostoma in position. U. S. National 



Museum, Catalogue No. 62701. 

 3c. (X 2.) Matrix of the specimen represented by fig. 3b. 



The specimens represented by figs. 3, 2a-b are flattened in a fine 

 argillaceous shale from locality 621, Middle Cambrian : Sixteen 

 Mile Canyon, Meagher County, Montana. 



