86 SMITHSONIAN M ISCKI.LANEOUS COLLECTIONS VOL. IO3 



characterized by a normal glabella on which two pairs of furrows are 

 clearly impressed. At a point immediately in front of the eye the 

 fixigene is al)out one-third the glabellar width. Divergence of the 

 facial suture in front of the eye develops moderately large anterior 

 angles. The brim width is about two-thirds the glabellar length in- 

 cluding the occipital ring. The slightly convex preglabellar area is 

 about two-thirds the width of the rim. Little curvature exists in the 

 rear half of the glabella, but the forward part turns down sharply. 

 The preglabellar area continues that slope, but the rim is turned 

 toward a horizontal position. Surface granulose, as usual. 



Orr formation; (loc. 32t) Fandango Spring Canyon, Dugway 

 Range, Utah. 



Holotype. — U.S.N.M. No. 108797a; paratype, No. 108797b. 



IDDINGSIA MISSOURIENSIS, new species 



Plate 16, Figures 21-26 



This is a rather prolific species, associated with Bcrkcia, Ptero- 

 cephalia, and other genera. Besides the numerous cranidia several 

 libragenes also represent the species. The glabella, tapering to a some- 

 what truncated front, has three pairs of well-developed furrows. The 

 width of the flaring brim equals about two-thirds of the glabellar 

 length. In the middle the flat rim is wider than the preglabellar area. 

 The slightly convex preglabellar area continues the downward slope 

 of the anterior portion of the glabella, but the nearly flat rim has a 

 less steep slope. At the anterior end of the eye the fixigene is one- 

 third as wide as the glabella. It rises sharply from the dorsal furrow 

 but is in itself not very convex. The strongly bowed eyes are situated 

 far back, practically in contact with the occipital furrow. An eye line 

 extends forward from the eye to the anterior glabellar lobe. Longi- 

 tudinally the cranidium is strongly convex, the relief being attained 

 by a slight curvature of the posterior half of the glabella and a strong 

 down-curving of the anterior half, continued by the slope of the brim. 

 Laterally the glabella rises little above the level of the palpebral lobes, 

 but the posterolateral limbs are sharply depressed. At the eye lines 

 the fixigenes slope abruptly downward to the anterior angles. A small 

 node occurs on the well-defined occipital ring. 



The rather large libragene has a long stout genal spine. At the eye 

 the fixigene rises steeply to the ocular platform which has a globular 

 convexity. The rim is flat and the suture intramarginal at least for 

 half and possibly all the distance to the center. None of the specimens 

 preserves the doublure which probably maintains its width across the 



