398 CAMBRIAN BRACHIOPODA. 



(14n) Limestone about 310 feet (94.5 m.) above the Lower Cambrian on the east side of the pass about 7 miles 

 (11.2 km.) east of Resting (Freshwater) Springs, which is in the southwest corner of T. 21 N., R. 8 E., on Amargosa ' 

 River, in the southeastern part of Inyo County, California. 



Middle? Cambrian: (32k) Limestones about 1,550 feet (472.4 m.) above the top of the quartzitic sandstones 2 miles 

 (3.2 km.) southeast of Muskrat Spring, on the northwest face of Grantsville Peak, Stansbury Range, Tooele County,Utah. 



Obolus mcconnelli decipiens n. var. 



Plate XXIII, figures 4, 4a-b. 



A form that appears to be a broad variety of Obolus mcconnelli (Walcott) occurs abun- 

 dantly in the arenaceous shales and interbedded limestone of the Upper Cambrian of the Silver 

 Peak Range, Esmeralda County, Nevada. Most of tlie material is badly preserved, and some 

 of the specimens afford fine illustrations of distortion of outline by compression. The variety 

 differs frona the species in being uniformly broader and also in having more strongly marked 

 concentric strise. It differs from the variety pelias in being of an average greater propor- 

 tional width. 



Formation and LOCALiTy. — TTpper Cambrian: Emigrant formation [Turner, 1902, p. 265] at the following locali- 

 ties: (7v) shales 4.25 miles {6.S km.) south-southeast of Emigrant Peak; (7x) limestone about 2.5 miles (4 km.) south- 

 east of Emigrant Pass; and (8r) shales about 8 miles (12.8 km.) southeast of Emigrant Peak; all in the Silver Peak 

 quadrangle (U. S. Geol. Survey), Esmeralda County, Nevada. 



Middle Cambrian: (7r) Calcareous shales 4 miles (6.4 km.) south-southeast of Emigrant Peak, Silver Peak quad- 

 rangle (U. S. Geol. Survey), Esmeralda County; and (8m) hmestone near the south end of the high ridge 4 miles 

 (6.4 km.) northeast of Osceola, White Pine County; both in Nevada. 



(14n) Limestone about 310 feet (94.5 m.) above the Lower Cambrian on the east side of the pass about 7 miles 

 (11.2 km.) east of Resting (Freshwater) Springs, which is in the southwest comer of T. 21 N., R. 8 E., on Amargosa 

 River, in the southeastern part of Inyo County, California. 



^ Obolus mcconnelli pelias (Walcott). 



Plate XXIII, figures 3b, 3c; Plate XXXIX, figures 5, 5a-c. 



Obolus [Lingulella) pelias Walcott, 1905, Proc. U. S. Nat. Mus., vol. 28, pp. 330-331. (Described and discussed as 

 a new species.) 



This form was originally described [Walcott, 1905a, pp. 330-331] as a distinct species, 

 but, with the large collections obtained in 1906 from various horizons of the Middle Cambrian, 

 it is found to have close relations to Oholus mcconnelli of the lower portion of the Middle Cam- 

 brian. It ranges from about the central portion of the IMiddle Cambrian up into the Ordovician. 



The variety differs from 0. mcconnelli in being proportionally shorter and broader, and 

 from the variety decipiens, of the Upper Cambrian, in being, on the average, slightly narrower. 



The outer surface of the shell is marked by clearly defined concentric lines that are slightly 

 irregular, and narrow, fine, radiating undulations or costse toward the frontal margins. When 

 unusually well preserved, the surface also shows very fine, irregular, concentric strise between 

 the concentric lines. The inner lamellas of the shell are marked by fine radiating striae and 

 the inner surface by more or less numerous punctse. For its size the shell may be considered 

 as relatively thin. 



Formation and locality. — Upper Cambrian : (54r) Drift pieces of limestone from the west slope of the Wasatch 

 Range; and (34q) shales about 3,800 feet (1,158.2 m.) above the Brigham quartzite [Walcott, 1908a, p. 8], in Wasatch 

 Canyon; both east of the Lakeview Ranch, about 5 miles (8 km.) north of Brigham, Boxelder County, Utah. 



(32g) About 2,575 feet (784.9 m.) above the Cambrian quartzitic sandstones in a blue limestone about 2 miles 

 (3.2 km.) southeast of Muskrat Spring, on the northwest face of Grantsville Peak, Stansbury Range, Tooele County; 

 (33d) thin-bedded blue limestone at the base of the first high point southwest of the J. J. Thomas ranch, on the east 

 side of the Fish Spring Range, Juab County; and (30j) about 950 feet (289.6 m.) above the Middle Cambrian and 

 2,450 feet (746.8 m.) below the top of the Upper Cambrian near the base of the arenaceous shales and limestones form- 

 ing le of the Orr formation [Walcott, 1908f, p. 176], on Orr Ridge, about 5 miles (8 km.) south of Marjum Pass, House 

 Range [Walcott, 1908f, PI. XIII], Millard County; all in Utah. 



(7s) Shale of the Emigrant formation [Turner, 1902, p. 265], 4 miles (6.4 km.) south-southeast of Emigrant Peak, 

 Silver Peak quadrangle (U. S. Geol. Survey), Esmeralda County, Nevada. 



Middle Cambrian: (8j) About 575 feet (175.3 m.) above the unconformable base of the Cambrian in a shale which 

 corresponds in position to shale No. 4 of the Dearborn River section [Walcott, 1908f, p. 202], on the ridge between 



