212 ,). STAXI.KV-r.KoWN INDKX 'Ic ) NOLrMKS 21 TO 30 



Page 



Optical iiulustry. War-tinu' development of 30. lOo 



Oranoe group of Ala.ska 25. 201 



Okbigny. a. d', cited on classification of last stage of the Jurassic system 



26. 298 



demarcation between Cretaceous and Eocene 25, 321 



Okbitosphkxoids and alisphenoids, Mammal and reptile 24, 242 



Orcadian formations, Stratigraphy of Middle Old Red 27, 370-378 



Okhoviciax and Cambrian faunas of Newfoundland 25, 138 



Silurian polar faunas ; R. S. Bassler 22, 92 



Siluric systems, Contacts between 25, 286 



— at Glenogle. British Columbia, Lower 24. o2 



— brachiopoda 25. 421 



, Comparison of lithologic. stratigraphic, and geographic range of. 25,428 



, List of 25, 424-427 



— - conglomerates of the Galena-Trenton sei'ies 25, 265 



— dolomite, Coralline algje in 24. 115, 607 



— fauna from southeastern Alaska ; Edwin Kirk 29, 143 



— flor.is 30, 507 



— ii-oii ores of Wabana. Xcw foiiiidlaiKl. Fossil alg;c of the 26, 148 



— limestone 28, 166 



of Pennsylvania discussed by A. W. (irabau 28. 167 



— limestones in Wisconsin, Fluorite in 29, 104 



— paleogeography. New Points in 29, 88 



— rocks of Hudson Bay region 30, 342 



— Silurian boundary. Inconsistencies in drawing the 27. 463 



— strata beneath the Healdton oil field, Oklahoma : S. Powers 28, 159 



Ordovicic of the Atlantic region 27, 573 



— Siluric section of the Mingan and Anticosti islands : Charles Scluichert 



and W. H. Twenhofel 21, 75, 677-716 



, Gulf of Saint Lawrence; W. II. Twenhofel and 



C. Schuchert 27, 312 



— species, Table of 27, 566 



— system, Anticosti island 21. 693 



Ore alterations. Relation of physiographic changes to; W. \V. Atwood. 26.106 



— deposit at Barth, Nevada, Iron- 24, 96 



— deposits. Role of colloidal migration in 26, 394 



— enrichment, Some chemical factors aftecting secondary sulphide. . . . 26, 393 



— , Oriskany iron 27, 64 



Oregon Bureau of Mines and Geology ; I. A. Williams 26, 137 



— Cascades, Geologic features of 29, 81 



— , Contribution to the geology ol' eastern 21, 791 



— , Corals from Cretaceous and Tertiary of 27, 174 



— .Fauna of the Siphonalia Sutterensis zone in the Roseburg quadrangle 



26, 169 



— , Marine Oligocene of 29, 297, 303 



— , Oil field of 28, 593 



— , Oligocene ( ? j of 25, 154 



— , Review of the fauna of the Rattlesnake Pliocene of eastern 26, 169 



