NO. 5 UPPER CAMBRIAN TRILOBITES — RESSER 63 



be concave. Since the very heavy eye bands are elevated, most of the 

 fixigene may lie below the level both of the dorsal furrow and of the 

 eye. The moderate-size eyes vary considerably in position. Libragene 

 unknown. 



Pygidium characterized by a stout axis in which two or more seg- 

 ments are indicated. The axis is from a half to two-thirds the length 

 of the pygidium and stands above the dorsal furrow. Pleural lobes 

 flat, extending fanwise into marginal spines. Pleural furrows strong 

 and pleural grooves usually visible. Marginal spines usually rather 

 blunt, forming a serrate edge. As the genus is now constituted they 

 number from one to five on a side, depending on the degree of fusion. 



ELLIPSOCEPHALOIDES ARGUTUS, new species 



Plate 10, Figures 5, 6 



Several cranidia from the Ram Creek area retain sufficient of their 

 characters to warrant description. The cranidium is broad. The 

 almost parallel-sided glabella extends nearly the full length of the 

 cranidium. In cross section it stands entirely above the shallow dorsal 

 furrow and the fixigenes which slope gently down from it. The 

 occipital furrow is clearly defined both on the glabella and fixigenes, 

 and three pairs of glabellar furrows are traceable. The fixigenes 

 between' the eyes and the dorsal furrow are about as wide as the 

 glabella at the same point. Unfortunately the eyes are not completely 

 preserved, but appear to have been of normal size, shape and position. 



Sabine formation; (loc. 12s) Ram Creek, 15 miles south of Canal 

 Flats, British Columbia. 



Holotype.— v. S.N M. No. 108735a; paratype. No. 108735b. 



ELLIPSOCEPHALOIDES BRISCOENSIS, new species 



Plate 10, Figure 7 



One of a dozen or more cranidia is figured. E. briscoensis is 

 narrower than E. argutus from the same region. Because of this 

 feature it bridges the gap between the genotype and the narrow forms. 

 The glabella is rectangular with rounded anterior angles and has two 

 or three pairs of glabellar furrows represented by elongate pits. In 

 width the brim measures less than a fourth the glabellar length. It 

 has a peculiar narrow elevation in the middle, and also has a faintly 

 defined narrow rim. As a whole the brim is slightly convex and is 

 set in a horizontal position. On the sides the brim passes into the 

 anterior fixigenes which maintain its level. In fact the outer margins 

 of the fixigenes are curved up and back to the genal angles so that 



