yO SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. IO3 



size. The brim width equals about haU the length of the glabella, 

 including the occipital ring. It is gently concave with a rather wide 

 rim indicated by a slight change in curvature. The cranidium is 

 slightly convex in both directions. 



The associated hypostoma is almost circular in outline, and is 

 striated on the wide flange which surrounds the convex but depressed 

 central elevation. 



The plump pygidium with an axis extending nearly the full length 

 terminates in a postaxial ridge. 



Weeks formation ; (loc. 3oi) 5 miles south of Marjum Pass, House 

 Range, Utah. 



Ilolotypc. — U.S.N.M. No. 108760a; paratypes, Nos. io876ob-e. 



MARYVILLIA LOPERI, new species 

 Plate 12, Figures 36-38 



This species is found at two localities in arkosic, calcareous, and 

 quartzitic sandstone. It averages rather large in size compared to 

 other western species. The glabella tapers forward to the rounded 

 front in the usual manner, and is a little longer than in the other 

 species here described. At the eyes the fixigenes are slightly more 

 than half the glabellar width. The eyes are normal in size and position. 

 The brim width is about one-third the glabellar length. A shallow 

 anterior furrow separates a slightly thickened rim. In cross section 

 the cranidium is moderately and evenly convex, but longitudinally it 

 is rather flat. 



The associated pygidium is likewise rather convex in cross section, 

 but longitudinally proportionately has greater convexity than the 

 cranidium. The prominent axis occupies nearly three-fourths the 

 length of the pygidium. In exfoliated specimens three pleural grooves 

 are visible on each side. 



Sawatch formation; (loc. 6a) Taylor Peak, 4 miles south of Ash- 

 croft; (loc. 6) Italian Mountain, 15 miles northeast of Crested lUitte. 

 Colorado. 



Holotype. — U.S.N.M. No. 108761a; paratype. No. 108761b. 



MARYVILLIA ALBERTA, new species 

 Plate 13, Figures 1-4 



This species is founded on a single exfoliated cranidium, and a 

 pygidium from a nearby locality is referred to it. The cranidium, 

 typical in all respects, has a large glabella that tapers to a rounded 

 frontal outline. Exfoliated specimens have a strongly developed keel. 



