NO. 5 UPPER CAMBRIAN TRILOBITES RESSER 7 



CHARIOCEPHALUS BULLA, new species 

 Plate i, Figures 7-11 



Several cranidia and a pygidium are placed in this moderate-sized 

 species. C. bulla is a large-eyed form and hence resembles C. bellus 

 and C. tenerus. 



The glabella is essentially quadrate, with rather strongly marked 

 furrows on the exfoliated holotype. The anterior outhne is nearly 

 straight between the broadly rounded anterior corners, and the narrow 

 brim is only slightly thickened. Fixigenes are confined to the palpebral 

 lobes and at their widest point are a little less than half the width of 

 the glabella. The long eyes do not reach the posterior furrow, and in 

 front, they end exactly at the outer edge of the dorsal furrow, and 

 hence are relatively shorter than in C. bellus or C. tenerus. The 

 glabella is convex laterally with the greatest curvature near the dorsal 

 furrow. Longitudinally the greatest curvature is toward the anterior 

 end. Fixigenes are considerably curved and slope downward from 

 the moderately deep dorsal furrow. The pygidium is somewhat 

 narrow and rather convex, with the axis standing wholly above the 

 pleural lobes. As a whole the pygidium slopes rearward at a moderate 

 rate, terminating with an abrupt slope. In fact, the rear end of the 

 axis slightly overhangs the border. The pleural lobes form triangular 

 platforms that drop off to the slightly flattened border, which becomes 

 rather narrow at the rear of the axis. 



Honey Creek limestone ; (loc. 37V) West Timbered Hills. Arbuckle 

 Mountains, Oklahoma. 



Holotype. — U.S.N.M. No. 108633a; paratype, No. 108633b. 



CHARIOCEPHALUS TERES, new species 



Plate i, Figures 12, 13 



This large-eyed species, resembling C. tenerus, is represented by a 

 few cranidia, none of which is complete. The illustrated holotype is 

 partially exfoliated and the anterior portion of the glabella abraded. 



The glabella is somewhat ovate, owing more to the rounded front 

 margin and rounded anterior angles than to the slight constriction 

 toward the rear. The furrows are developed normally but may be 

 fainter than the average species from the region. Incomplete preser- 

 vation prevents an exact description of the brim but it seems to be 

 wide and slightly upturned, though not thickened. The fixigenes are 

 nearly half the width of the glabella. Eyes are very long, extending 

 from the occipital furrow well beyond the lateral course of the facial 

 suture, and therefore exceed the glabella in length. Surface punctate. 



