OBOLID^. 417 



scars is indicated about halfway between the main vascular sinuses and the posterolateral 

 margm of the valve. 



Observations. — This species is characterized by its finely granular surface, short cardinal 

 area, and relatively thick shell. It has the general form of Oholus lamhorni (Meek) and 

 Oholus willisi ( Walcott) , but it differs from both of these species in having a granulated surface 

 and shorter cardinal area. ' It appears to be the Ivower Cambrian form that is represented in 

 the Middle Cambrian by Oholus willisi and in the Upper Cambrian by Oholus lamhorni. 



The specific name is given in honor of Prof. Eugene A. Smith, State geologist of Alabama. 



Formation and locality. — Lower Cambrian: (17b) Rome ("Montevallo") formation, 4 miles (6.4 km.) south of 

 Helena; and (56c) Rome {" Montevallo") formation, along road just north of Buck Creek, 1.125 miles {1.8 km.) northeast of 

 Helena; both, in Shelby County, Alabama. 



Obolus tetonensis Walcott. 

 Plate IX, figures 5, 5a-d. 



Obolus tetonensis Walcott, 1901, Proc. U. S. Nat. Mus., vol. 23, p. 684. (Characterized and discussed as below as a 



new species.) 

 Obolus tetonensis Walcott, 1905, idem, vol. 28, p. 327. (Copy of preceding reference, the species being given as new 



and no reference being made to the preceding citation.) 



The general form, convexity, and appearance of this species are so much like those of Oholus 

 matinalis (Hall) (PI. VIII) that a general description is unnecessary. It varies from that 

 species in the shorter, more transverse dorsal valve, and the narrower outline of the ventral valve 

 toward the beak. 



This species occurs in great abundance in the thin-bedded limestone in the upper portion 

 of the Cambrian section of the Teton Range, Wyoming, in association with Billingsella colorado- 

 ensis (Shumard) and Llngulella (Lingulejns) acuminata meeki (Walcott). The forms from this 

 horizon are illustrated by Plate X, figures 5, 5a,, and 5b. What appears to be the same species 

 occurs nearly 700 feet lower in the section in a thin-bedded sandstone. Specimens from this 

 horizon are represented by Plate X, figures 5c and 5d. The dor=r,l valve (5d) is broader and 

 more transverse posteriorly than the dorsal valve from the u" : ."r horizon. 



Tliis form owes its specific name to its occurrence in the Te.on Mountains of Wyoming. 



Formation and locality. — Upper Cambrian : (161) Limestone or the south side of West Gallatin (Gallatin) River, 

 northwest of Hamilton on the north side of the Gallatin Valley; (152b) « east side of Dry Creek, below Pass Creek, 

 Threeforks quadrangle (U. S. Geol. Survey); and (148a) limestone of the Gallatin formation at the head of Bostwick 

 Canyon [Iddings and Weed, 1894, areal geology sheet^], in the Bridger Range, Livingston quadrangle (U. S. Geol. 

 Survey); all in Gallatin County, Montana. 



Middle Cambrian: (4m) Sandstones about 150 feet (45.7 m.) aboAO the unconformable base of the Cambrian; and 

 (4e) limestones about 950 feet {289.6 m.) above the unconformable base of the Cambrian; both in the divide at the head of 

 Jackson Creek (locally known as Sheep Creek), a creek fiowing into Jackson Lake about 0.5 mile (0.8 km.) south of its 

 northwestern corner, Teton Mountains, Grand Teton quadrangle (U. S. Geol. Survey), Uinta County, Wyoming. 



(4h) About 375 feet (114.3 m.) above the base of the Cambrian in limestone interliedded in the Flathead shales of 

 Peale [1893, p. 21], 1 mile (1.6 km.) north of the junction of East Gallatin and West Gallatin (Gallatin) rivers, 4 miles 

 (6.4 km.) east-northeast of Logan, Tln-eeforks quadrangle (U. S. Geol. Survejr), Gallatin County; and (4x) limestone 

 interbedded in the Wolsey shale [Weed, 1900, p. 285], at the base of a butte in Belt Park, about 6 miles (9.6 km.) 

 northwest of Neihart, Little Belt Mountains quadrangle (U. S. Geol. Sur\'ey), Cascade County; both in Montana. 



(3e) Thin-bedded limestones less than 400 feet (121.9 m.) above the quartzitic sandstones of the Cambrian, at 

 Ophir, Oquii'rh Range, Tooele County, Utah. 



(14x) About 400 feet (122 m.) above the bottom of Tombstone Gulch in the Abrigo limestone [Ransome, 1904, p. 3], 

 in the northwest suburb of Bisbee [Ransome, 1904, areal geology sheet], Cochise County, Arizona. 



1 Obolus tetonensis leda Walcott. 



Ohohis tetonensis leda Walcott, 1908, Smithsonian Misc. Coll., vol. 53, No. 3, p. 63. (Characterized as below as a new 

 variety.) 



This is the Upper Cambrian representative of Oholus tetonensis Walcott of the Middle Cam- 

 brian of the Teton Mountains. Stratigraphically it occurs over 2,000 feet higher in the Cambrian 



a This species is somewhat doubtfully identified from this locality. 



t> Iddings, J. P., and Weed, W. H., Livingston folio (No. 1), Geol. Atlas U. S., U. S. Geol. Siurvey, 1894. 

 62667°— VOL 51, pt 1—12 27 



