NO. 3 CAMBRIAN AND OZARKIAN TRILOBITES (fj 



specific name do not show intergradations relative to size of border 

 as stated in the original description, but, as can be seen from the 

 illustrations, large and small maintain the same relative proportions. 

 Formation and locality. — Middle Cambrian: (31) Chisholm for- 

 mation. Chisholm mine, southwest slope of Ely Mountains, 3 miles 

 (4.8 km.) northwest of Pioche, Lincoln Country, Nev. 



Genus ANORIA Walcott 



Anoria Walcott, 1924, Smithsonian Misc. Coll., Vol. 75, No. 2, p. 54. 



Description. — Dorsal shield broadly oval in outline, moderately 

 convex, with a strong axial lobe. Cephalon with a large glabella 

 outlined by strong dorsal furrows on the sides that terminate an- 

 teriorly in slight pits : a very slight depression separates the glabella 

 from a narrow rounded frontal rim : the sides of the glabella diverge 

 from about midway of its length towards the front : posterior glabel- 

 lar furrows slightly defined : occipital furrow well marked and occipi- 

 tal ring strong with a node at its center. 



Fixed cheeks are narrow in front of the palpebral lobes and widen- 

 ing posteriorly to merge into rather short postero-lateral limbs that 

 have a well-defined intermarginal furrow. Palpebral lobes narrow 

 with posterior end slightly back of the transverse median line of 

 the cranidium ; ocular ridge extending across the cheek to the dorsal 

 furrow. 



F'ree cheeks moderately large with a furrow defining a wide 

 border beginning near the suture at the front and curving inward to 

 join the posterior edge of the postero-lateral limb. Genal spines long 

 and strong. A wide doublure extends forward from the genal angle 

 and thickens as it passes beneath the cranidium, and apparently 

 without a median suture. The general course of the facial suture 

 diverges from the front of the cephalon to the occipital margin ; is 

 entirely intramarginal, rounds off the corners of the glabella, passes 

 outward around the comparatively straight palpebral lobes, and behind 

 the eyes diverges more rapidly, cutting the posterior margin at a 

 distance from the glabella equal to about one-third the length of it, 

 thus leaving broadly triangular postero-lateral limbs. 



Thorax in the type species with seven segments. Axis wide, each 

 segment having a median tubercule and a faintly impressed furrow. 

 The pleurae are short, increasing in length relative to the width of 

 the axis posteriorly ; each pleura has a deep and wide furrow dying 

 out rapidly near the end where the pleura begins to taper to a blunt 



