76 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 75 



which is delimited by a very gentle smooth furrow from the frontal 

 limb. The facial sutures curve outward and forward from the base 

 of the eye and recurve abruptly inward so as to cut across the frontal 

 rim at a very slight angle ; their course in front is unknown. 



Free cheeks broad, large and terminating in a strong, long spine. 



The few fragments of the thorax were found which indicate that 

 the segments were similar in form to those of B. splendens. 



The associated pygidium has a strong axial lobe crossed by four 

 narrow sharp furrows that separate four strong, slightly convex 

 segments and a terminal portion that is nearly as long as the seg- 

 mented portion. The axis is a little more than one-half the length of 

 the pygidium and merges into it at the end of a very steep slope ; 

 the lateral lobes slope rapidly from near the axis down to the broad 

 planulate margin that extends from the anterior margin entirely 

 around the lateral and posterior margins ; the transverse furrows of 

 the axis extend diagonally backward and fade out on the margin along 

 with the pleural furrow of each segment represented in the pygidium. 



Surface marked by very fine, raised, irregular inosculating lines. 



An associated hypostoma is illustrated by figure 7, plate 20. It is 

 not unlike that of Dikeloccphalus ininnesotensis Owen* but varies 

 in details. 



Dimensions. — The largest cranidium has a length of about 50 mm. 

 and pygidium of 50 mm. 



Observations. — This species differs from D. splendens in the char- 

 acter of the frontal limb and rim, and in the proportions of the 

 glabella. The pygidia associated with the cranidise of the two species 

 are much alike, but the axial lobe of B. splendens is more slender. 



Formation and locality. — Ozarkian: (i6t') Mons formation. Thin 

 layers of limestone interbedded in gray argillaceous shale, Brisco 

 Range, north side of Sinclair Canyon about 500 feet (1524 m.) 

 above creek and a little west of Radium Hot Springs. 



(i7n) Thin layer gray nodular limestone interbedded in argillace- 

 ous shale, at north side of Stoddart Creek Canyon near its mouth, 

 6 miles (9.6 km.) south of Sinclair Canyon, Stanford Range, on east 

 side of Columbia River Valley, British Columbia, Canada. 



Ozarkian. (64n) Mons formation (Lower). Near base of le of 

 field section. Cliff on southeast side of Mons Glacier, above head of 

 Glacier Lake Canyon valley about 50 miles (80.5 km.) northwest of 

 Lake Louise Station on Canadian Pacific Railway, Alberta, Canada. 



^ Smithsonian Misc. Coll., 1914, Vol. 57, No. 13, pi. 81, fig. 3. 



