OBOLID^. 397 



At most localities this species occurs within 200 feet of the base of the Middle Cambrian. 

 In the House Range section of Millard County, Utah, however, it has been found at about 1,500 

 feet above the Middle Cambrian, and at other localities a very closely allied form, which was 

 'originally described as a species, "Oiolus (Lingulella) pelias" [Walcott, 1905a, p. '330], occurs 

 in the middle portion of the Middle Cambrian and extends into the Upper Cambrian. This I 

 have now designated as the variety pelias. Another variety, decipiens, occurs in the Upper 

 Cambrian. 



The variety pelias, as a whole, is slightly narrower in the dorsal valve and somewhat more 

 obtuse in the ventral valve. The variety decipiens is still shorter and broader in proportion as 

 compared with the typical Oholus mcconnelli. 



This is one of the most persistent forms in the Middle Cambrian section of the Cordilleran 

 region, ranging, as it does, with its two varieties, from near the base of the Middle Cambrian 

 well up into the Upper Cambrian or through 4,500 feet of limestone. It also has a wide geo- 

 graphic distribution in the Cordilleran region, extending from British Columbia to southeastern 

 California. 



Formation AND LOCALITY.— Middle Cambrian: (14s) About 2,300 feet {701 m.) above the Lower Cambrian and 2,700 

 feet (823 m.) below the Upper Cambrian, in the Ogygopsis zone of the Stephen formation [Walcott, 1908f, p. 210], at the great 

 "fossil bed" on the northwest slope of Mount Stephen, above Field, on the Canadian Pacific Railway; (57f) about 2,200 feet 

 (670.6 m.) above the Lower Cambrian and 2,800 feet (853.4 m.) below the Upper Cambrian, in the limestones forming 1 

 of the Stephen formation [Walcott, 1908f, p. 209], about 0.5 mile (0.8 km.) east of the " fossil bed " on the northwest slope 

 of Mount Stephen, above Field, on the Canadian Pacific Railway; (58j) about 1,900 feet (579 m.) above the Lower 

 Cambrian and 3,100 feet (945 m.) below the Upper Cambrian, near the base of the limestone forming 2 of the Stephen 

 formation [Walcott, 1908c, p. 238 (7)], on the east side of Mount Stephen about 3,000 feet (914 m.) above the Cana- 

 dian Pacific Railway track 3 miles (4.8 km.) east of Field; and (58r) about 1,800 feet (548.6 m.) above the Lower 

 Cambrian and 3,200 feet (975.4 m.) below the Upper Cambrian, in the limestones forming 2 of the Stephen formation 

 [Walcott, 1908f, p. 211], in the amphitheater between Mounts Stephen and Dennis, above Field on the Canadian 

 Pacific Railway; all in British Columbia, Canada. 



(35g)a About 4,100 feet (1,250 m.) above the Lower Cambrian and 860 feet (262 m.) below the Upper Cambrian in 

 the shaly limestones in 2 of the Eldon limestone [Walcott, 1908f, p. 209 ("Lingulella sp.")], at the north end of the 

 amphitheater northwest of the main ridge of Mount Bosworth; and (57o and 67k) about 2,500 feet (762 m.) above the 

 Lower Cambrian and 2,475 feet (754 m.) below the Upper Cambrian in the limestone forming 1 of the Stephen formation 

 [Walcott, 1908f, p. 209], on Mount Bosworth; both north of the Canadian Pacific Railway between Hector and Stephen, 

 on the Continental Divide between British Columbia and Alberta, Canada. 



(581 and 58w) About 1,225 and 1,300 feet (373 and 396 m.), respectively, above the Lower Cambrian in the shales of 

 the Stephen formation [Walcott, 1908a, p. 3], northeast slope of Castle Mountain facing the amphitheater, north of the 

 Canadian Pacific Railway, Alberta. 



(3j) Above the quartzitic sandstones in a shale corresponding in position to the upper part of shale No. 6 of the 

 Dearborn River section [Walcott,. 1908f, p. 202], about 6 miles (9.6 km.) west-northwest of Scapegoat Mountain on the 

 Continental Divide between Bar Creek and the headwaters of the south fork of North Fork of Sun River, Coopers Lake 

 quadrangle (U. S. Geol. Survey), Powell County, Montana. 



(31c) About 900 feet (274.3 m.) above the Brigham quartzite and 3,300 feet (1,005.8 m.) below the Upper Cambrian, 

 in the limestone forming lb of the Ute limestone [Walcott, 1908f, p. 196]; and (54p) about 525 feet (160 m.) above the 

 Brigham quartzite and 3,665 feet (1,127.1 m.) below the Upper Cambrian in the shales forming 2f of the Ute limestone 

 [Walcott, 1908t, p. 197]; both in Blacksmith Fork Canyon about 10 miles (16.1 km.) east of Hyrum, Cache County, Utah. 



(34n) Shales about 100 feet (30.5 m.) above the Tintic quartzite [G. 0. Smith, 1900, p. 1], near the summit of the 

 ridge between Mammoth and Eureka; and (34s) about 1,700 feet (518 m.) above the Tintic quartzite in the Mammoth 

 limestone of G. O. Smith [1900, p. 1, and historical geology sheet], in the saddle above and a little east of the Centennial 

 Eureka mine, near the summit of the ridge between Mammoth and Eureka; both in the Tintic special quadrangle 

 (U. S. Geol. Survey), Juab County, Utah. 



(30p) About 125 feet (38 m.) above the Cambrian quartzitic sandstones, on the north side of Ogden Canyon, about 

 1 mile (1.6 km.) above its mouth, east of Ogden, Weber County; and (Sly) thin-bedded limestone about 125 feet 

 (38 m.) above the Cambrian quartzitic sandstones in the Wasatch Mountains, 1 mile (1.6 km.) northwest of Geneva 

 (Copenhagen), east of Brigham, Boxelder County; both in Utah. 



(lOy) About 2,900 feet (884 m.) above the Lower Cambrian and 1,500 feet (457.2 m.) below the Upper Cambrian in 

 the central part of the limestone forming la of the Marjum limestone [Walcott, 19081, p. 179], about 1 mile (1.6 km.) 

 south-southwest of Marjum Pass; and (14v) shales of unknown stratigraphic horizon collected 1 mile (1.6 km.) south of 

 Rainbow Valley; both in the House Range [Walcott, 1908f, PI. XIII], Millard County, Utah. 



(8m) Limestone near the south end of the high ridge 4 miles (6.4 km.) northeast of Osceola; and (lOw) shaly lime- 

 stones about 5 miles (8 km.) northeast of Osceola, on the east side of the Snake Range; both in White Pine County, 

 Nevada. 



a This species is somewliat doubtfully identified from this locality. 



