NO. 5 UPPER' CAM RRIAN TRILOBITES RESSER 69 



fairly good material which includes all the various parts. In the 

 striation and structure of the brim, the larger size of the eye, and the 

 wider border of the pygidium, this species approaches Coosia. How- 

 ever, it seems better to place the species on the Maryvillia side of the 

 boundary and recognize these discrepancies. 



The glabella tapers to a rounded front, and in exfoliated specimens 

 is clearly outlined by a deep dorsal furrow. The fixigenes, convex in 

 cross section, are a little less than half the glabellar width. Rather 

 heavy eye lines are accentuated in appearance by the abrupt slope 

 adjacent to them. The width of the brim is equal to half the length 

 of the glabella exclusive of the occipital ring. The rim is demarcated 

 by a change in slope. Heavy striations occur on the front edge of 

 the rim. Eyes rather large, being nearly as long as the brim is wide. 



The libragene shows that the suture is intramarginal for a short 

 distance. Its rather wide and strongly striated rim increases in width 

 slightly from the front to the rounded genal angle. The ocular plat- 

 form is very narrow opposite the anterior portion of the eye. At its 

 widest point, at the rear of the eye, it is not much broader than the 

 rim. The associated hypostoma is nearly circular in outline with the 

 central convex portion occupying less than half of its area. The outer 

 upturned flange is striated in a manner similar to that of the rims on 

 the cranidium and libragene. 



The associated p3'gidium is strongly convex in lateral direction 

 and slopes very steeply longitudinally. The axis, occupying only a 

 little more than half the length of the tail, is not strongly differentiated 

 from the pleural lobes, although it stands completely above them. 

 Axial rings and the anterior pleura are faintly indicated. 



Weeks formation ; (loc. 32w) Fandango Spring Canyon, Dugway 

 Range, Utah. 



Holotype. — U.S.N.M. No. 108759a; paratypes, Nos. io8759b-e. 



MARYVILLIA MARJUMENSIS, new species 

 Plate 12, Figures 33-35 



This species is well represented, and on several pieces of rock 

 cranidia and pygidia lie close together. One fairly large cranidium is 

 figured, but even larger ones are present in the collection. Af. marjum- 

 ensis is fully typical of Maryvillia in that the pygidial axis extends 

 nearly the full length of the pygidium. As usual the glabella tapers 

 to a rounded front and in exfoliated specimens is clearly defined by 

 a rather deep dorsal furrow, which on the outer test is shallow. Fixi- 

 genes average just about half the glabellar width. Eyes are of normal 



