54 SMITHSONIAN MIScEr.r.ANEo^^s collections vol. 103 



BYNUMIA VENUSTA, new species 

 Platk 9, Figures 21-28 



This abundantly represented species is characterized chiefly by its 

 narrow cranidial shape, which forms an isosceles triantjle. Longi- 

 tudinally the curvature is not great, and the relatively wide brim 

 continues the gradual slope of the anterior portion of the glabella. 

 The libragene figured, the first for the genus, constitutes almost a 

 quarter circle, the outer margin increasing its rate of curvature toward 

 the genal angle. Several pygidia are figured, one with a complete test 

 and two partially exfoliated examples. The latter show how the axial 

 rings and pleural furrows and grooves are developed on the under 

 side of the test. 



Sullivan formation ; (loc. 64s) Ranger Brook Canyon, Sawback 

 Range, Alberta. 



llolotypc. — U.S.N.M. No. 108725a; paratypes, Nos. io8725b-f. 



BYNUMIA ROBSONENSIS, new species 



Plate 9, Figures 30-34 



One species of Bynumia occurs in the Robson District, far north 

 of the localities of the other species. This species is characterized by 

 its triangular outline, with the base being longer than the sides. The 

 photographs fail to bring out the sharpness of the brim, owing to the 

 high convexity developed near the tip. 



Lynx formation (Sullivan equivalent) ; (Iocs. 19m, L) lyatunga 

 Mountain, Mount Robson, British Columbia. 



Ilolotype. — U.S.N.M. No. 108726a; paratypes, Nos. 108726b, c. 



BYNUMIA SULCATA, new species 

 Plate 9, Figures 35, 36 



A single small distinctive cranidium has the usual triangular outline 

 and average shape of other species in the Sawback Range. Because 

 of the depth of the dorsal furrow, B. sulcata is closest to B. arguta, 

 but carries this development much further. Not only is the dorsal 

 furrow deeply impressed both on the sides and in front, but in addi- 

 tion, the brim, set in a nearly horizontal position, does not continue 

 the glabellar slope. This is a remarkable development in a specimen 

 that is not completely exfoliated. The side view shows the distribution 

 of convexity. 



Sullivan formation; (loc. 64s) Ranger Brook Canyon, Sawback 

 Range, Alberta. 



Holotype.—U.S.'^M. No. 108727. 



