Introduction _______________________________________ Previous work._________________________________ Present study._________________________________ Scope of the report______________________________ Acknowledgments _______________________________ Stratigraphic and geographic distribution of the cephalopods__________________________________ Ozark Plateaus_. _______________________________ Mississippian system________________________ Lower Mississippian series _______________ Walls Ferry limestone.______________ Lower and Upper Mississippian series. .

Pa<"e FIGURE 1. Index map showing the principal mountain ranges in the Great Basin region in northwestern Utah ___ /2 2. Sketch map of the Oquirrh Mountains and South Mountain showing the locations of the Rogers Canyon, Bingham, and Curry Peak sequences _____.__________________________________ 3 3. Generalized columnar sections of the Rogers Canyon and Bingham sequences in the Oquirrh Mountains_ 4 4. Sketch map of the Oquirrh Mountains showing location of type and reference sections _______ _ _ 5 5. Columnar sections showing the development of upper Paleozoic rock-stratigraphic divisions in the Bingham sequence ________________________.___________________________________ 6 6. Columnar sections showing the development of upper Paleozoic rock stratigraphic divisions in the Rogers Canyon sequence __________________._____________________________________ 8 7-12. Photographs of: 7. Typical exposures of Rogers Canyon sequence _____________________ _ 12 8. General features of the lithology of the lowermost part of the Lake Point Limestone _ __ __ ]"3 9. The upper two-thirds of Erda Formation and the basal part of Kessler Canyon Formation _ 15 10. Typical exposures of reference section of the West Canyon Limestone and the basal portion of the Butterfield Peaks Formation in Soldier Canyon __________________-__________ 24 11. Typical exposures of the middle part of the Butterfield Peaks Formation at the head of White Pine Canyon tributary of Middle Canyon __.________________________________ _ 27 12. Typical exposures of the Jordan (limestone) marker bed (a thick cherty limestone) within the base of the Clipper Ridge Member of the Bingham Mine Formation at the type locality of the member in Middle Canyon ______-______________________________ _ 28 13.

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PLATE 1. Columnar sections showing Madison Limestone-Amsden Formation contact relations in central and western Wyoming and south-cenrtral Montana.

Girtyspira circumsecta. A new name, Retispira eliasi, is proposed to replace Bucanopsis (Retispira?) reticulata Elias, 1958 [not Bellerophon reticulatus M'Coy, 1844], both of which belong in Retispira. A lectotype is designated for Glabrocingulum (Ananias) nevadense (Walcott), of late Meramecian age, from the Diamond Peak Formation of Nevada, and this species is figured by photographs for the first time. PREVIOUS WORK cies that may have come from beds of Late Mississippian age cannot be distinguished. CHESTERIAN GASTROPODS UTAH Sadlick and Nielsen (1963) described and figured some Late Mississippian pleutrotomariacean gastropods of the Chainman Shale from several localities in west-central Utah. Lunulazona costata Sadlick and Nielsen was described from the lower part of the formation on the basis of specimens collected in the foothills east of Granite Mountain, Juab County. Lunulazona sp. A [ = L. sadlicki n. sp.] came from beds of Chesterian age that they identified as Chainman Shale, 0.3 miles (0.5 km) northeast of Leppy Peak, Elko County, Nev., near Wendover, Utah. Mourlonia sp. [ = Ptychomphalina sp. of this report] is from that locality. Glabrocingulum binodosum Sadlick and Nielsen was based upon specimens collected near the top of the Chainman in the Foote Range, Millard County, Utah, and G. quadrigatum Sadlick and Nielsen, also from the upper part of the Chainman, was described from specimens collected on the northern slope of the Burbank Hills, Millard County. Sadlick and Nielsen included in G. quadrigatum specimens from the northern part of the Confusion Range, which we herein place in another species (Glabrocingulum (Glabrocingulum) confusionense n. sp.). They also described but did not figure Glabrocingulum. n. sp. aff. G. inflatum (Elias) (probably = G. (Ananias) seminudum Gordon and Yochelson), from near the top of the formation on the southern slope of the Burbank Hills. Finally, Sadlick and Nielsen cited the occurrence ofWorthenia tenuilineata Girty in the upper part of the Chainman. We herein assign this species to the subgenus W. (Yochelsonospira). Sadlick and Nielsen's paper covers approximately 10 percent of the gastropod fauna of the Chainman Shale described in this report. NEVADA The first late Chesterian gastropod was described from Nevada only relatively recently. Mount (1973) described and illustrated Straparollus (Euomphalus) pancakensis from the Adetognathus unicornis Conodont Zone in the Pancake Range in northern Nye County. The gastropod was found 20 feet (6 m) above the base of the Ely Limestone. Gordon and Yochelson (1983) described a large faunule of gastropods from a single bed, about 1.7 ft (0.5 m) thick, in the upper part of the Diamond Peak Formation at the northern end of the White Pine Range in White Pine County. This assemblage is associated with Cravenoceras hesperium , the name-bearer of the ammonoid zone of that name. This zone is Late Mississippian (late Chesterian) in age, though not latest Mississippian. More than half the species also occur in the Chainman Shale in wes...