CANADIAN PERIOD. 61 



side respectively near the anterior end of the pygidium, bend abruptly, 

 and extend backward parallel with the first, and project beyond the border 

 as converging posterior spines. The third and outer pan- of segments com- 

 mence anteriorly at the dorsal furrows, where they are very narrow, extend 

 outward a little, then curAdng abruptly backward they lie parallel with the 

 others and form raised lateral margins of considerable but unequal width 

 to the pygidium, and thence they extend posteriorly as an outer pair of 

 converging spines. Axis prominent, especially at its apex, where it terminates 

 in a moderately distinct angle, about one-quarter wider anteriorly than 

 posteriorly, well defined by the nearly straight dorsal furrows, and marked 

 by five or six distinctly defined segments, which cross it almost transversely, 

 but with a slightly sinuous course. 



Length of the pygidium along the median line, seven millimeters; 

 greatest transverse diameter, nine millimeters. 



The collections contain only the pygidium of this species, and I have 

 therefore refen-ed it doubtingly to Bicellocephalus, although it might perhaps, 

 with equal propriety, be referred to Amphion. It has a general resemblance 

 to the pygidium of Z>. magnificus Billings, and a still closer resemblance to 

 D. f Gora Billings, from the Quebec group of Canada. 



Position and locality. — Strata of the age of the Quebec group of Canada; 

 Schellbounie, Schell Creek range, Nevada. 



