weeks] PALEONTOLOGY, PETROLOGY, AND MINERALOGY, 1904. 91 
O'Harra (Cleophas C). 
1. The geology and mineralogy of the Black Hills region. 
Black Hills, South Dakota. Papers read before the Black Hills Mining Men's 
Assoc, pp. 119-127, 1904. 
Describes the general topographic and geologic features and character of the 
rocks of the region, and gives notes upon the occurrence, character, and 
geologic relations of the ore deposits, chiefly gold ores. 
Oliphant (F. H.). 
1. [In discussion of paper by R. Pearson on " The discovery of natural 
gas in Sussex, Heathfield district."] 
Inst. Mg. Engrs. [Engl.], Trans., vol. 26, pp. 505-506 [1904]. 
A short note in regard to the distribution of natural gas in the United States. 
;2. Petroleum. 
U. S. Geol. Surv., Min. Res. of U. S. for 1903, pp. 635-718, 1904. 
Includes a table showing the stratigraphic position of petroleum-producing 
horizons in the Appalachian and Lima-Indiana fields. 
Ordonez (Ezequiel). 
II. El mineral de Angangueo, Michoacan [Mexico]. 
Mexico, Inst. Geol., Par., t. 1, pp. 59-74, 1 pi., 4 figs., 1904. 
Discusses vein phenomena and the occurrence of silver veins in a matrix of 
pyrite and galena. 
2. Las aguas subterraneas de Amozoc [Mexico]. 
Mexico, Inst. GeoL, Par., t. 1, pp. 117-120, 1904. 
Discusses the occurrence of underground water in the State of Puebla, Mexico. 
J3. Las cenizas del volcan de Santa Maria. 
Mexico, Inst. Geol., Par., 1. 1, pp. 229-234, 1904. 
Describes ashes from the volcano Santa Maria, Guatemala. 
Ortmann (A. E.). 
1. Leber die Decapoden-Gattungen Linuparus und Podocrates. 
Centralbl. f. Min., Geol., u. Pal., pp. 713-714, 1901. 
Discusses the relationships of these genera of Crustacea. 
Orton (Edward, jr.) and Peppel (S. V.). 
1. The lime resources of Ohio available for Portland cement manu- 
facture. 
Ohio Geol. Surv., 4th ser., Bull. no. 3, pp. 88-101, 1904. 
Discusses the occurrence, character, and geologic relations of limestones in 
Ohio suitable for use in manufacture of cements. Gives a table with many 
analyses of limestone. 
Osann (A.). 
p.. Beitrage zur Geologie und Petrographie der Apache (Davis) Mts., 
Westtexas. 
Tschermak's Min. & Petrogr. Mitt., N. F., Bd. 15, pp. 394-456, 2 pis. and I 
fig., 1896. 
Describes the general geology of the region, the occurrence of igneous and 
Carboniferous and Cretaceous sedimentary rocks, and the petrographie char- 
acters of the igneous rocks. 
