NO. 5 UPPER CAMBRIAN TRILOBITES — RESSER 73 



about one-fourth the glabellar length. Thickened rim wider than the 

 nearly flat preglabellar area. Fixigenes narrower than the rim, convex 

 adjacent to the eye. The small, strongly bowed eyes are set parallel 

 to the dorsal furrow. Suture diverges normally anterior to the eye. 

 Relief of the cranidinm is considerable as shown in the illustrations. 

 Anterior angles and posterolateral limbs are moderately depressed. 

 Surface closely granulose. 



The associated pygidium is similar to certain forms assigned to 

 MaryvilUa or CooscUa. Its axis extends about three-fourths the 

 pygidial length. Pleural furrows weakly developed. A rather wide, 

 flat, border is underlain by a striated doublure. 



Sullivan formation ; (loc. 66m) 4^ miles northwest of Banfl^, Saw- 

 back Range, Alberta. 



//o/oM'/'r.— U.S.N. M. No. 108764a; paratypes, Nos. To8764b, c. 



COOSIA Walcott, 191 1 

 COOSIA CANADENSIS, new species 



Plate 13, Figures 18-20 



Several pygidia and one cranidium have been segregated. It is a 

 rather small species for the genus but typical in most other respects. 

 The glabella, tapering to a rounded front, is without furrows. The 

 concave brim width is about one-third the glabellar length. A flat 

 rim demarcated by a shallow anterior furrow about equals the pre- 

 glabellar area in width. Fixigenes narrow, their width being less than 

 one-fourth the glabellar width at botli ends of the eye lobe. The 

 fixigenes rise from the dorsal furrow, but the palpebral lobes have a 

 nearly horizontal position. Laterally the glabella is slightly convex, 

 and longitudinally the cranidium attains moderate convexity by de- 

 pression of the brim and the steepness of the slope in the anterior part 

 of the glabella. The pygidium has a prominent axis occupying a little 

 more than half its length. In dorsal view a postaxial ridge makes the 

 axis appear much longer than it is. Axial rings are faintly shown, 

 but the pleural furrows and grooves are so completely fused that only 

 the anterior pair remains. 



Sullivan formation; (loc. 641) Glacier Lake Canyon Valley, 48 

 miles northwest of Lake Louise, Alberta. 



Holotype. — U.S.N.M. No. 108766a; paratype, No. 108766b. 



COOSIA ALBERTENSIS, new species 



Plate 13, Figures 25-28 



Although apparently an abundant species, only a few specimens 

 have been segregated in the collection. This is not a large species. 



