PATERINID^. 363 



the West is from Nevada to Montana, and in the Appalachian region from eastern New York 

 to Alabama. At first, on account of its highly ornamented surface, I was led to think that it 

 might belong to a distinct genus from Micromitr'^,, but comparisons with M. sculptilis (Meek) 

 and the simple ornamentation of M. (Paterino'^ hella (Billings) show transitions in the orna- 

 mentation between the otherwise distinct forms. 



Varieties of Micromitra (IpJiidella) pannula. — In collections from the Middle Cambrian 

 limestones of northern Utah and southern Idaho, material has been selected for illustration 

 which represents varieties of form and surface markings of Micromitra (IpJiidella) pannula 

 (White) that might be given specific names were it not for the intermediate phases which occur 

 at the same locality with the varieties. The specimens from near Malade, Idaho (PI. IV, figs. 

 2, 2a-g), and many not illustrated, show a wide variation in outline and surface. Another 

 series from near Ophir, Utah (PI. IV, figs. 4, 4a-f), illustrate the entire evolution of the 

 "pannula" type of surface, from the concentric strife to the fine network of oblique, raised 

 lines dividing the surface into minute, diamond-shaped depressions. In some of the examples 

 from Malade the ridges are so sharp and clear that the surface has a honeycomb-like appearance 

 (PI. IV, fig. 2g). 



The surface of M. (/.) pannula (White) is composed of porelike pits formed by obliquely 

 crossing, elevated lines (PI. IV, figs. In-ls), and for convenience of reference the forms showing 

 variations from this may be separated into the varieties vfialadensis und opJiirensis (pp. 364-365). 



Formation and locality. — Upper Cambrian: (96) Limestones near the ford on the Cedartown road, 1.5 miles 

 (2.4 km.) south of Rome, Floyd County, Georgia. 



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, 1908fj^ p. 210], at the "fossil bed," on the 

 northwest slope of Mount Stephen, above Field on the Canadian Pacific Railway; (57j) about 2,000 feet (609.6 m.) 

 above the Lower Cambrian in the limestones forming 2 of the Stephen formation [Walcott, 1908c, p. 237 (6)], just 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 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 Canadian Pacific 

 Railway track, 3 miles (4.8 km.) east of Field; and (35k) Burgess shale member of the Stephen formation on the west 

 slope of the ridge between Mount Field and Wapta Peak, 1 mile (1.6 km.) northeast of Burgess Pass, above Field; 

 all in British Columbia. 



(S7g) About 1,700 feet (518 m.) above the Lower Cambrian and 3,250 feet (991 m.) below the Upper Cambrian in 

 the siliceous shales forming 2d of the Stephen formation [\\^alcott, 1908f, p. 211], on Mount Bosworth, north of the 

 Canadian Pacific Railway between Hector and Stephen, on the Continental Divide between British Columbia and 

 Alberta, Canada. 



(4q and 4(i') 315 and 310 feet (96 and 94.5 m.), respectively, above the unconformable base of the Cambrian and 

 190 and 185 feet (57.9 and 56.4 m.), respectively, above the top of the quartzitic sandstones in shales and limestones 

 which correspond in position to the upper part of shale No. 6 of the Dearborn River section [see Walcott, 1908f, p. 202], 

 on the ridge between Gordon and Youngs creeks, about halfway between Gordon Mountain and Cardinal Peak, Ovando 

 quadrangle (U. S. Geol. Survey), Powell County; (303t) limestone northeast of Logan, Threeforks quadrangle (U. S. Geol. 

 Survey), Gallatin County; and (149a) limestone at the forks of Pole Creek, above Cherry Creek basin, Threeforks 

 quadrangle (U. S. Geol. Survey), Madison County; all in Montana. 



(55c and 163) a Spence shale member of the Ute limestone [Walcott, 1908a, p. 8], about 50 feet (15.2 m.) above the 

 Brigham quartzite and 2,755 feet (839.7 m.) below the Upper Cambrian, in a ravine running up into Danish Flat 

 from Mill Canyon ; and (59f ) limestones immediately underlying the Spence shale member of the Ute limestone [T^'alcott, 

 1908a, p. 8], in a saddle north of the creek which flows into Mill Canyon from the west; both about 5 miles (8 km.) 

 west-southwest of Liberty and 15 miles (24.2 km.) west of Montpelier, Bear Lake County, Idaho. 



(6b and 54s) Dark blue-gray Langston limestone [Walcott, 1908f, p. 198] just above the Cambrian quartzitic 

 sandstones, north side of Twomile Canyon, near its mouth, 2 miles (3.2 km.) southeast of Malade, Oneida County, 

 Idaho. 



(aiv) 650 feet (198 m.) above the Lower Cambrian and 3,750 feet (1,143 m.) below the Upper Cambrian, in shales 

 at the top of the limestone forming la of the Howell formation [Walcott, 1908f, p. 182], northeast side of Dome Canyon, 

 about 4 miles (6.4 km.) west-southwest of Antelope Springs; and (31s) 490 feet (149.4 m.) above the Lower Cambrian 

 and 3,925 feet (1,196.3 m.) below the Upper Cambrian, in the pinkish, argillaceous shale forming Id of the Howell for- 

 mation [Walcott, 1908f, p. 182], south side of Dome Canyon, about 1 mile (1.6 km.) below the divide and 3 mUes 

 (4.8 km.) west-southwest of Antelope Springs; both in the House Range [Walcott, 1908f, PI. XIII], Millard County, Utah. 



(14t) Limestone lying on the slope between the Cambrian quartzite and the massive blue limestone 100 feet 

 (30.5 m.) above. Mount Nebo Canyon, 3 miles (4.8 km.) southeast of Mona, Juab County; (55u) limestones about 200 



a This species also occurs in Locality 65e. 



