NO. 5 UPPER CAMBRIAN TRILOBITES RESSER II 



sloping sides. Longitudinally the moderate convexity is practically 

 confined to the anterior lobe. The brim consists of a narrow band in 

 a slightly upturned position. The fixigenes at their widest point are 

 about half the width of the glabella and the long eyes have a nearly 

 circular curvature. They extend forward to the dorsal furrow and 

 back practically to the occipital furrow. The narrow libragene has a 

 long, slender, straight genal spine which extends outward at a con- 

 siderable angle to the axis. The pygidium is characterized by a wide 

 tapering axis with three rings and terminal segment. Fusion has not 

 entirely eliminated the pleural grooves. Pleural platforms narrow 

 because of the long slope to the marginal furrow. 



Honey Creek limestone {Ptychaspis beds) ; (loc. Qiq) 8 miles 

 southeast of Mountain View, Wichita Mountains, Oklahoma. 



Holotype. — U.S.N.M. No. 108640a; paratypes, Nos. io864ob-e. 



CHARIOCEPHALUS ULRICHI, new species 

 Plate 2, Figures 9-14 



This is another large and well-represented species, similar to C. 

 wichitaensis. It fact the two are so similar that a formal description 

 of this species is not needed. C. ulrichi differs in several respects, the 

 most notable of which are the presence of ,a narrow anterior fixigene 

 and greater curvature of the eyes so that the rear portion of the 

 fixigene is relatively more contracted. The increased curvature of 

 the eye is accompanied by a slightly greater relative width of the 

 palpebral lobe making it equal to half the glabellar width. 



The associated pygidium of C. ulrichi differs considerably from the 

 others found in Oklahoma. Its axis slopes rearward into the dorsal 

 furrow, which grows more shallow in the same direction, so that the 

 rear portion of the axis merges into the pleural lobes. The whole 

 pygidium slopes in all directions from the median point of the 

 anterior axial segment. 



Honey Creek Hmestone {Ptychaspis beds) ; (loc. 9y) 2 miles south- 

 east of Canyon Creek, Wichita Mountains, Oklahoma. 



Holotype. — U.S.N.M. No. 108641a; paratypes, Nos. io864ib-d. 



CHARIOCEPHALUS MAGNUS, new species 



Plate 2, Figures 15-17; Plate 12, Figure 13 



This beautiful, large species is represented by the complete holo- 

 type and several imperfect cranidia. 



The quadrate glabella is slightly constricted in its middle portion. 

 It stands well above the fixigenes and is convex laterally, with a 

 circular profile. Longitudinally the considerable convexity is confined 



