NO. 5 UPPER CAMBRIAN TRILOBITES RESSER 79 



The axis occupies only about half the pygidial length. It is slightly 

 concave in a longitudinal direction and slopes abruptly to the wide 

 border. Furrows are visible on the axis and in the anterior portions 

 of the pleural platforms. A slight postaxial ridge extends to the rear 

 margin. 



Secret Canyon shale; (loc. 23b) ridge east of Hamburg Ridge, 

 Eureka District, Nevada. 



Holofypc— U.S.N. M. No. 108784a: paratype. No. 108784b. 



PTEROCEPHALINA UTAHENSIS, new species 



Plate 15, Figures 7-1 i 



A very fine species of Pteroccphalina has been found in western 

 Utah. This genus should be represented in other formations of the 

 same age throughout the cordilleran region. 



The glabella tapers to a truncated front, where the dorsal furrow 

 is almost obliterated. Three pairs of glabellar furrows are faintly 

 defined, the posterior pair having a very irregular course. The wide, 

 gently concave brim occupies nearly half the glabellar length. Fixi- 

 genes are narrow, being only one-third the glabellar width between 

 the eyes and the dorsal furrow. Eye bands are heavy. Anterior to 

 the eyes the facial suture diverges moderately to meet the wide brim. 

 The axis occupies less than half the length of the pygidium and stands 

 above the small pleural platforms. Three rings are clearly defined. 

 Three pleural furrows, decreasing in depth from posteriorly, are 

 visible. The wide border is nearly flat, and has a wide medial 

 indentation. 



Orr formation ; (loc. 33d) east side of Fish Spring Range, Utah. 



Holofypc— U.S.N. M. No. 108785a; paratype, No. 108785b. 



BURNETIDAE, new family 



Kobayashi established the Dokimocephalinae as a subfamily in the 

 Solenopleuridae Angelin, to include the genera Bunictia, Dokiino- 

 cephahis, Iddingsia, Elkia, and AcroccpJialitcs. The last-named genus 

 superficially resembles the others, but since it is a Middle Cambrian 

 Atlantic Province genus and therefore far removed from the others 

 in time and space, its relationship may be questioned. In my opinion 

 Acrocephalites is related to Solenopleura and should remain in that 

 family. The Burnetidae are not from the Solenopleura line but have 

 descended from trilobites found in the cordilleran region. To the 

 named genera must be added Berkeia, and several others still 

 undescribed. 



