NO. 5 UPPER CAMBRIAN TRILOBITES RESSER IO3 



Longitudinally the relief of the cranidium is not great but because 

 both the dorsal and anterior furrows are deep the relative relief 

 between the several parts is accentuated. In cross section the con- 

 vexity of the glabella and sharp rise of the fixigenes to the eyes as 

 well as sharp depression of anterior angles and posterolateral limbs. 

 give both the front and rear margins of the head considerable curva- 

 ture. The surface is covered by evenly spaced granules. 



St. Charles limestone; (loc. 546) Blacksmith Fork, Bear River 

 Range, Utah. 



Holotype.— U.S.N. M. No. 108829. 



TAENICEPHALUS STRIATIFRONS, new species 

 Pl.\te 21, Figures 1-3 



The second species from the locality is characterized by a rather 

 strongly tapering glabella and a vertically striated brim. The fixigenes 

 are rather evenly covered by granules but only a few are found on 

 the more elevated parts of the glabella. Brim width is considerably 

 less than one-third the cranidial length. The longitudinal convexity 

 is not great nor does the cross section attain high relief, even though 

 the glabella and the fixigenes are convex. 



St. Charles limestone; (loc. 54e) Blacksmith Fork, Bear River 

 Range, Utah. 



Holofypc— U.S.N. M. No. 108833a; paratype. No. 108833b. 



TAENICEPHALUS UTAHENSIS, new species 

 Plate 21, Figures 4-6 



This third species from the locality is represented by several 

 cranidia. It is most like T. striatifrons in shape and general appear- 

 ance but differs in having considerably less surface ornamentation. 

 The average size glabella tapers at a normal rate and has the usual 

 sets of furrows faintly outlined. The brim width is just about one- 

 third the cranidial length. The rim is about two-thirds the width of 

 the preglabellar area in the center. Both are convex. The fixigenes 

 are narrow and the eyes of normal size and shape. Longitudinally the 

 head is not very convex, most of it being attained in the anterior 

 portion. In cross section the fixigenes rise rather abruptly from the 

 dorsal furrow. The anterior angles are considerably depressed but 

 the posterolateral limbs are not. 



St. Charles limestone; (loc. 54e) Blacksmith Fork, Bear River, 

 Range, Utah. 



Holotype. — U.S.N.M. No. 108834a ; paratype, No. 108834b. 



