NO. 24 PTARMIGANIA STRATA RESSER 63 



moderate even curvature throughout. In other words, the cranidium 

 is not highly convex. Brim narrow, consisting of a simple concave 

 extension on which a rim is outlined by a slight increase in curvature 

 of the brim. Fixigenes average a little less than one-third the width 

 of the glabella. Eye ridges heavy. Eyes nearly one-third the length 

 of the cranidium and set at a moderate angle to the median line. Neck 

 furrow shallow but clearly defined. Neck ring expanded, possibly 

 bearing a small nuchal spine. 



The pygidium has the characteristics already given with the generic 

 description. The pleural ribs are rounded and fusion has completely 

 eliminated the pleural grooves. 



Surface covered by fine anastomosing lines. 



Locality 54s. 



Holotype and paratype. — U.S.N.M. Nos. 98565a-g. 



TAXIOURA MAGNA, n. sp. 

 Plate 14, figs. 1-5 



This species is represented by the nearly complete holotype cra- 

 nidium and a number of fragmentary examples. A libragene and a 

 single pygidium has been assigned to the species. 



This species is characterized by a very long glabella with nearly 

 parallel sides except for constriction anterior to the eye lines. Anterior 

 margin rounded. Three pairs of shallow, irregular glabellar furrows 

 are clearly indicated. The occipital furrow is fairly deep, particularly 

 on the sides, and the occipital ring is expanded, terminating in a small 

 blunt spine. Brim very narrow consisting essentially of an upturned 

 rim. Fixigenes average nearly half the width of the glabella. Eye 

 lines very heavy. Eye less than one-fourth the length of the cranidium 

 and set at only a small angle to the course of the dorsal furrow. The 

 libragene is marked by a steep slope from the eye to the horizontal, 

 slightly thickened border. Genal spine heavy and possibly long. 



A rather large pygidium is assigned to the species. It is like that 

 of T. typicalis in shape and relative size as well as in the characteristics 

 of the margin. It is particularly characterized by the flatness of the 

 upper surface of the ribs and the fact that fusion has not completely 

 eliminated the pleural grooves. Surface rather coarsely marked by 

 irregular lines and granules. 



Locality 54s. 



Holotype and paraty pes.— U.S.N.M. Nos. o,8566a-c. 



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