NO. 3 CAMBRIAN AND OZARKIAN TRILOBITES 129 



wider pygidium. The central portion of the glabella is fairly well 

 preserved and shows several depressions, indicating the position of 

 the glabellar and occipital furrows. Eyes situated far back, and the 

 manner in which the palpebral lobes are broken away indicates that 

 they were somewhat erect. 



The associated pygidium is shorter and wider than that of X. goni- 

 ocercum. 



Formation and locality. — Ozarkian : (6iq) Chushina formation. 

 Billings Butte (Extinguisher), above Hunga Glacier, Robson Peak 

 District, British Columbia, Canada. 



