NO. 5 CAMBRIAN TRILOBITES 34I 



These pygidia are placed in Bathyuriscus rather than Dolichome- 

 topus on account of the distinctness of the segments on the pleural 

 lobes. 



Formation and locality. — Aliddle Cambrian : Spence shale member 

 of the Ute formation: (55c) about 50 feet (15.2 m.) above the 

 Brigham quartzite, and 2,755 ^^^^ (839.7 m.) below the Upper Cam- 

 brian, in a ravine running up into Danish Flat from Mill Canyon, 

 about 6 miles (9.6 km.) west-southwest of Liberty and 15 miles (24.2 

 km.) west of Montpelier, Bear Lake County, Idaho. 



Also, Spence shale horizon of the Ute formation : (sse) about 100 

 feet (30.5 m.) above the Brigham quartzite, at the mouth of the first 

 small canyon south of Wasatch Canyon, east of Lakeview Ranch, 

 Boxelder County, Utah. 



BATHYURISCUS HAYDENI (Meek) 



Plate 46, figs. 2, 2a-b 



Bathyurus ? haydeni Meek, 1873, Sixth Ann. R^pt., U. S. Geol. Surv. Terr., 

 p. 482. (Detailed description of species and comparison with species 

 of several genera.) 



Description. — General form elliptical to elongate oval ; moderately 

 convex, with pleural lobes slightly flattened. Cephalon probably 

 semicircular with genal angles extended backward in short spines as 

 in closely allied species. Glabella narrow, convex, and expanding in 

 advance of the palpebral lobes to the broadly rounded front ; occipital 

 furrow strong, arching slightly forward from the sides tow^ards the 

 center; occipital ring strong, convex, and rising towards the center 

 as though it may have had a node or short spine near its posterior 

 margin ; the posterior pair of glabellar furrows are quite strong ; 

 they commence about opposite the center of the palpebral lobe and 

 extend obliquely backward and inward to a shallow connecting trans- 

 verse furrow which delimits a transverse posterior lobe about as wide 

 as the occipital ring; the next succeeding anterior pair of furrows 

 are short and inclined a little backward, while the third pair extended 

 directly inward as slight, short indentations, and the fourth very short 

 and distinct pair are directed slightly forward. 



Fixed cheeks narrow, with strong elongate palpebral lobes which 

 extend across them anteriorly as a narrow ridge to the dorsal furrow, 

 the lobe on each side being separated by a narrow furrow ; the eye 

 lobe appears to have been about one-fifth the length of the head ; 

 anteriorly the 'fixed cheek merges into a narrow area and posteriorly 



