516 HISTORICAL GEOLOGY. 



at Cincinnati, holding Coenograptus gracilis and three other species of Normanskill Grap- 

 tolites, also contain Triarthrns BecJcii and other characteristic Utica species (Ulrich, Am. 

 Geol., i.)- 



4. Echinodenns. — Among Crinoids, Fig. 708, Glyptocrinus decadactylus H., not 

 uncommon in New York, Ohio, Kentucky, and other states ; also Dendrocrinus Cin- 

 cinnatiensis Meek, and species of the genera Heterocrinus, Porocrinus, Carabocrinus, 

 Reteocrinus, Ca7iistrocriniis, Stenocrinus, Ohiocrinus^ Tocrinus, Anomaloci'imis, Mero- 

 crinus. Fig. 703 represents a large Star-fish from the blue limestone of Chicinnati, as 

 figured by J. G. Anthony, the original of which was 4 inches across. 



There are also Cystoids of the genera Agelacrinites, Lichenocrinus, Hemicystites, all 

 sessile species, and in this respect Actinia-like ; also Star-fishes of the genus Palceaster, etc. 



5. Brachiopods. — The figures of Brachiopods on page 507 are from specimens 

 obtained in the Cincinnati beds. Other characteristic species are Lingula quadrata, 

 Crania scabiosa, Zygospira modesta. 



6. Mollusks. — (a) Lamellibranchs. — Cypricardites Sterlingensis M. & W. 



(6) Gastropods. — 3Iiirchisonia Milleri H.; Cyrtolites ornatus Con., near Fig. 679 ; C. 

 imbricatus M. &W., Illinois; C. carinatus Miller and others ; Cyclonema bilix Con.; C. 

 Cincinnatiense Ulr., etc. ; Pleurotomaria Ohioensis H., etc. ; Cyclora parvula H. ; also 

 species of the genera Trochonema, Helicotoma, Metoptoma, etc. 



(c) Pteropods. — Species of Tentaculites, T. tenuistriatus M. & W., and T. Osivegoensis 

 M. & W., from Illinois, in the Cincinnati group; Theca parviuscula, H. ; Comdaria for- 

 mosa M. & D. ; C. Trentonensis H. 



(d) Cephalopods. — Some of the species, besides those figured, are Orihoceras ampli- 

 cameratum H. ; 0. coralliferum (4 inches broad) ; 0. transversum Miller ; Gompho- 

 ceras eos H. & Whitf., from Cincinnati; Actinoceras (Onnoceras) crebriseptum Hall; 

 Endoceras proteiforme H. ; Trocholites Ammonius. 



7. Crustaceans. — Asaphus platycephalus ; A. Canadensis Cha,pTa. 

 Ostracoids occur of the genera Leperditia, Cytheropsis, Beyrichia, Pnmitia. 



Some of the genera and species from the Cincinnati beds are the following : Cceno- 

 graptus gracilis H., Fig. 699 ; Dendrograptus gracillimus Lesq. ; D. tenuiramosus Wale. ; 

 Dicranograpttis ramosus H., Fig. 702 ; Diplograptus Whitfieldi H. ; D. spinulosus H. ; 

 Climacograptus typicalis H. ; species of Zaphrentis ; Inocaulis arbuscula Ulv. ; the Tren- 

 ton species, Glyptocrinus decadactylus; Heterocrinus Canadensis; H. geniculatus; 

 species of Palceaster, Protaster, Codaster ; of Lingula, Strophomena, Orthis, Bhyncho- 

 nella, Crania; Tellinomya alta ; Fig 709, Avicula demissa ; Ambonychia radiata ; species 

 of Lyrodesma, Modiolopsis, Orthodesma; Conularia Trentonensis, C. formosa M. & D., 

 Fusispira terebriformis, Endoceras proteiforme, Cyrtoceras ornatum ; Trinucleus concen- 

 tricus, Calymene Christyi H., Dalmanites breviceps H., Proetus parviusculus H. ; species 

 of Primitia, Beyrichia, Leperditia, Cytheropsis. 



In the Eureka district, Nevada, according to Walcott, the Pogonip limestone, which 

 rests on the Cambrian and is 2700' thick, contains in the lower part a mixture of Potsdam 

 and Silurian species ; the genera Dicellocephalus, Agnostus, Ptychoparia being largely devel- 

 oped, and some species identical with Wisconsin Potsdam species ; and with these are 

 Acrotreta gemma and some other Calciferous species ; but above the middle of the Pogo- 

 nip beds the characteristic Cambrian features are absent, and there occur the genera 

 Beceptaculites, Monticidipora, Pletirotomana, Maclurea, Cyphaspis, Bathyurus and 

 Asaphus; and still higher the genera Orthis, Strophomena, Cyrtolites, Orihoceras, Endo- 

 ceras, Tellinomya, Amphion, Ceraurus, Asaphus, Leperditia, Beyrichia, which appear to 

 indicate the horizon of the Lower Trenton, or the Chazy. Between the Pogonip limestone 

 and the Devonian there are 500' of Eureka quartzyte and 1800' of Lone Mountain lime- 

 stone, and only Halysites catenulatus has been found here. See Walcott, U. S. G. 8. 

 Rep., 4to, 1884. 



