168 CAMBEIAN BRACHIOPODA. 



4u. Middle Cambrian: Shalea in the Gallatin formation of Peale [1893, PI. IV], northwest side of canyon, 0.5 

 mile (0.8 km.) south of Helena, Jefferson County, Mont. (L. S. Griswold and C. D. Walcott, 1898). 

 Obolus (Westonia) ella. 

 Lingulella helena. 



4v (115 feet below 4q; same horizon as 5j; see 3j and 4q). Lower Cambrian: About 200 feet (61 m.) above the 

 unconformable base of the Cambrian and 75 feet (22.9 m.) above the top of the quartzitic sandstones, in a 

 shale which corresponds in stratigraphic position to shale No. 6 of the Dearborn River section [see Walcott, 

 1908f, p. 202], Gordon Creek, 6 miles (9.6 km.) from South Fork of Flathead River, Ovando quadrangle 

 (U. S. G. S.), Powell County, Mont. (C. D. Walcott, 1905). 



Micromitra (Iphidella) pannula. 

 Obolus (Westonia) ella. 

 Acrothele coUeni. 

 *Acrothele panderi. 

 *Wimanella simplex 



Ptychoparia sp. 



Albertella helena Walcott. 



Bathyuriscus productus (Hall and Whitfield)?. 



Bathyuriscus? sp. 



4w (same horizon as 4q). Lower Cambrian: About 315 feet (96 m.) above the unconformable base of the Cambrian 

 and 190 feet (57.9 m.) above the top of the quartzitic sandstones, in a shale which corresponds in position 

 to shale No. 6 of the Dearborn River section [see Walcott, 1908f, p. 202], on Youngs Creek, about 5 miles 

 (8 km.) from its junction with Danaher Creek, Ovando quadrangle (U. S. G. S.), Powell County, Mont. 

 (CD. Walcott, 1905). 



Wimanella simplex. 



Ptychoparia sp. 



Zacanthoides sp. 



4x (a little higher than 5f ; see 4g, 4h, 4k, and 5f). Middle Cambrian: Limestone interbedded in the Wolsey shale 

 [Weed, 1900, p. 285], at the base of a biitte in Belt Park, about 6 miles (9.6 km.) northwest of Neihart, Little* 

 Belt Mountains quadrangle (U. S. G. S.), Cascade County, Mont. (C. D. Walcott, 1898). 



Micromitra pealei. 



Obolus tetonensis. 



Scenella. 



4y (=54t, which see). (For stratigraphic position and association, see p. 149.) (C. D. Walcott, 1898.) 

 Obolus (Westonia) ella. 

 Billingsella coloradoensis. 



6. Middle Cambrian: Siliceous shale on Hayward Creek, Braintree, Dedham quadrangle (U. S. G. S.), Norfolk 

 County, Mass. (W. P. Rust, 1891). 

 Acrothele gamagei. I Agraulos quadrangularis (Whitfield). 



Hyolithes shaleri Walcott. I Paradoxides harlani Green. 



Grabau [1900] cites the following additional species from this locality: 

 Fucoids or trails?. I Hyolithes ? haywardensis Grabau. 



Parmophorella acadica (Hartt). I Ptychoparia, rogersi Walcott. 



5a (=54t, which see). (For stratigraphic position and association, see p. 149.) (C. D. Walcott, 1898.) 

 Obolus wortheni. 

 Lingulella desiderata. 

 Billingsella coloradoensis. 



6b (=54s, which see). (For stratigraphic position and association, see p. 152.) (C. D. Walcott, 1893.) 

 For the species occurring at this locality, see Locality 54s. 



5o (=54t, which see). (For stratigraphic position and association, see p. 149.) (C. D. Walcott and L. D. Burling, 

 1906.) 

 Obolus wortheni. 

 *Acrotreta idahoensis. 

 Billingsella coloradoensis. 



Sf (a little lower than 4x). Middle Cambrian: Limestone interbedded in the Wolsey shale fW^eed, 1900, p. 285], 

 in Meagher County, on the road to Wolsey, about 4 miles (6.4 km.) south of the divide at the head of Saw- 

 mill Creek and 11 miles (17.7 km.) south of Neihart, Little Belt Mountains quadrangle (U. S. G. S.), Cascade 

 County, Mont. (C. D. Walcott, 1898). 



Micromitra pealei. 

 Obolus (Westonia) ella. 

 Lingulella desiderata. 



Scenella. 



Dorypyge? quadriceps (Hall and Whitfield). 



