INVERTEBRATE FOSSILS 549 



From the upper beds of the formation, at a point about 5 miles east of 

 Bald mountain, the following fossils were collected: Streptelasma n. sp. 

 (with trilobate calyx), Calapoecia sp. undet., Favosites sp. undet., Stroma- 

 tocerium, ? n. sp., Dalmanella testudinaria var., Leptscna unicostata, and 

 Rhynchotrema capax. These were determined by Mr E. 0. Ulrich, who 

 regards them as of Eichmond age. 



Near the divide at the head of Cedar creek the upper member of the 

 formation was found to be about 160 feet thick, and in the upper beds of 

 this member the following forms were found : Leptcena unicostata, Stro- 

 phomena fluctuosa, Dinorthis subquadrata (coarsely striated form), Rhyn- 

 chotrema capax. In the middle beds are Hdly sites gracilis (abundant), 

 Streptelasma sp. undet., Diplotrypa westoni, Dalmanella testudinaria var. 

 (D. meehiy W. & S.), and Zygospira n. sp. (without radial plications). 

 In the lower beds of the upper member, a short distance above the top 

 of the thick massive limestone member of the formation, were the follow- 

 ing fossils: Streptelasma n. sp. (with trilobate calyx), Dalmanella tes- 

 tudinaria var., Rhynchotrema increbescens ?, Trochonema umbilicata f, 

 Trochonema sp. undet., and Cyrtoceras sp. undet. (near C. lysander). 

 All these forms are of Eichmond age. 



A complete section of the Bighorn limestone is well exposed in Wolf 

 Creek canyon. Lying on the basal sandstone are about 200 feet of massive, 

 cream-colored, silicious limestone, typical of the lower portion of the 

 formation. This is overlain by the top member of purer, softer limestones 

 in part very fine grained and yielding Rhinidictya, Dicranopora near 

 fragilis, Ptilotrypa obliquata, P achy dicta sp. undet., Primitia sp. undet., 

 and numerous corals, a fauna of approximate Eichmond age. On Big 

 Goose creek similar rocks are found, 160 feet of massive limestone lying 

 on the basal sandstone and containing only a few maclurinas and coral 

 fragments. This is overlain by the top member, comprising 10 feet of 

 fine grained cream-colored limestone, 42 feet of massive, hard, light 

 cream-colored limestone, in part sandy and with small calcite geodes, 4 

 feet of coarse grained limestone filled with corals, including Halysites 

 gracilis (small-meshed form) and Columnaria thomii Hall (like C. 

 alveolata Goldfuss, but with separate corallites), 6 feet of sandy and pure 

 limestone layers alternating, and 40 feet of limestone, mostly soft, slabby, 

 and fine grained. Next above are 135 feet of massive cream-colored lime- 

 stones, cherty in lower part, belonging entirely or in greater part to the 

 Madison limestone, but containing only a few indeterminate coral frag- 

 ments. 



On South fork of Eock creek, 12 miles northwest of Buffalo, large num- 

 bers of fossils are weathered out of the reddish clay, due to the weathering 



