r 



NO. 5 UPPER CAMBRIAN TRILOBITES RESSER 2g 



St. Charles formation; (Iocs. 4y, 5e) Two Mile Canyon, Wasatch 

 Mountains, Idaho. 



Holotype. — U.S.N.M. No. 108670a ; paratype. No. 108670b. 



DRUMASPIS IDAHOENSIS, new species 



Plate 4, Figures 32-36 



This species is represented by many cranidia. The glabella tapers 

 slightly. Peculiar structure is shown by the occipital furrow, which 

 is narrow next to the dorsal furrow, then widens suddenly, main- 

 taining that width to the similar point on the opposite side. The rear 

 pair of glabellar furrows is interrupted in the middle both by growing 

 shallow and by making a reversed forward curve. The anterior pairs 

 show on exfoliated specimens. In cross section the glabella is rather 

 flat but stands completely above the dorsal furrow. In longitudinal 

 section it curves gently for most of its length, then turns down sharply 

 at the front. The narrow brim consists of a rim in horizontal position. 

 The fixigenes are a little less than one-third the glabellar width and 

 in their anterior portion decrease to about the width of the anterior 

 dorsal furrow. They slope downward rather evenly from the dorsal 

 furrow, their declivity increasing in the rear to meet the sharply 

 depressed posterolateral limbs, and anteriorly to join the rim. The 

 moderately bowed eyes attain a length equal to about half the length 

 of the glabella. 



St. Charles limestone; (loc. 4y) Two Mile Canyon, 2 miles south 

 of Malad, Wasatch Mountains, Idaho. 



Holotype. — U.S.N.M. No. 108671a; paratype. No. 108671b. 



DRUMASPIS ALBERTA, new species 



Plate 5, Figures 1-3 



The description of this species is based on several cranidia, the 

 most complete example being figured as the holotype. 



The quadrangular glabella has a slightly indented anterior margin. 

 Anterior angles rounded. In cross section the glabella is only slightly 

 arched above the dorsal furrow. Longitudinally there is considerable 

 elevation, most of which occurs in the anterior fourth. Brim narrow, 

 apparently with a narrow upturned rim. Fixigenes about half the 

 width of the glabella ; anterior portion reduced to brim width. Eyes 

 not strongly bov/ed, set at a wide angle to the dorsal furrow, forming 

 a fixigene of fairly even width for the rear two-thirds of the head. 

 3 



