so. 5 UPPER CAMBRIAN TRILOBITES RESSER 47 



dorsal furrow. Exfoliated specimens have the glabella much more 

 sharply defined, and glabellar furrows are represented by pits. The 

 eyes are slightly farther back than in A. albcrtensis. The suture 

 diverges in front of the eye and forms large posterolateral limbs 

 behind the eye. The middle portion of the brim projects somewhat. 

 In cross section the cranidium has considerable elevation, attained by 

 sharp curvature of the top of the glabella from which the postero- 

 lateral limbs bend downward with approximately the same slope. 

 Longitudinally the species is not greatly curved. 



Sullivan formation; (loc. 6^e) East Lyell Glacier, 48 miles north- 

 west of Lake Louise, Alberta. 



Holotype. — LT.S.N.M. No. 108702a; paratype, No. 108702b. 



PLETHOMETOPUS Ulrich, 1930 

 PLETHOMETOPUS ALBERTENSIS, new species 



Plate 12, Figure 13 



A single cranidium, typical of the genus in all respects is sufficiently 

 well preserved to warrant naming. The simple large glabella, indi- 

 cated by a faint dorsal furrow, is about three-fourths the length of 

 the head, and tapers slightly to a rounded anterior margin. A strong 

 occipital furrow separates a neck ring that extends into a short blunt 

 spine. Fixigenes narrow, measuring at the eyes about a fifth the 

 glabellar width. The posterolateral limbs are small and possibly short. 

 Eyes small, situated about the midpoint of the glabella. In cross 

 section the cranidium is rather evenly curved, while longitudinally 

 the curvature is much greater, particularly in the anterior half. As 

 a result the simple brim is convex in both directions. A faint broad 

 anterior furrow is visible in the anterior angles. 



Lyell formation; (loc. 20j) Tilted Mountain Brook, 97 miles east 

 of Lake Louise, Alberta. 



Holotype— \JSMM. No. 108755. 



KINGSTONIA Walcott, 1924 



KINGSTONIA ELECTRA, new species 



Plate 7, Figures 33-36 



This species is represented by a number of cranidia, but thus far 

 no pygidium which can be assigned to the species has been located. 

 On the outer surface the cranidium shows few features. It is highly 

 arched in both directions, becoming almost hemispherical. Indeed its 

 outline departs slightly from a semicircle only by a flattening of the 

 curvature at about the midpoint of the cranidial length. A narrow 

 brim is present. Exfoliated specimens sliow a clearly defined glabella, 



