NO. 5 UPPER CAMBRIAN TRILOBITES RESSER 89 



words, while the ensemble does not look so much like Iddingsia, the 

 separate features fall readil}^ within its generic limits. 



The glabella is large, nearly rectangular, slightly rounded in front, 

 and has three pairs of furrows. The neck ring carries a small spine. 

 Since the anterior facial suture diverges at a small angle and the 

 anterior margin is rather straight, the cranidium as a whole has a 

 quadrangular shape. The brim, divided almost equally between rim 

 and preglabellar area, equals about half the glabellar length exclusive 

 of the neck ring. At the anterior end of the eye the fixigene is less 

 than half the glabellar width. The eyes situated far back against the 

 occipital furrow are rather strongly bowed and have particularly 

 heavy palpebral furrows and eyebands. 



Mendha limestone; (loc. y]) i mile northwest of Italian Ranch 

 foothills, Quinn Canyon Range, Nevada. 



Holotype.—V.S.^M. No. 108802a; paratype. No. 108802b. 



IDDINGSIA ANATINA, new species 



Plate 17, Figures i, 2 



This neat species is characterized by its smooth, rounded glabella. 

 The occipital furrow is narrower than usual, but the neck. ring expands 

 in the center and has a long spine. The brim width equals the length 

 of the glabella exclusive of the occipital ring. Owing to the forward 

 projection of the anterior margin, the rim at its center exceeds the 

 width of the preglabellar area. Fixigenes are of average size and 

 shape, being peculiarly marked by the swellings in the inner rear 

 portion of the palpebral lobe. The evenly and sharply bowed eyes 

 have heavy bands. In cross section the evenly convex glabella rises 

 above the dorsal furrow. The fixigenes opposite the eyes are also 

 convex. Longitudinally the glabella is gently convex. The cranidium 

 as a whole slopes forward, its declivity being continued by the pre- 

 glabellar area as far as the anterior furrow, beyond which the rim is 

 turned up somewhat. Brim covered with vertical anastomosing lines. 



Honey Creek limestone; (loc. 9q) Blue Creek Canyon, Wichita 

 Mountains, Oklahoma. 



Holotype.—U.S.'NM. No. 108803. 



IDDINGSIA SIMPLICITAS, new species 

 Plate 17, Figures 3-9 



This prolific species, represented by many cranidia and several 

 Hbragenes was first regarded as representing a new genus. However, 



