148 BIBLIOGRAPHY OF NORTH AMERICAN GEOLOGY, 1906-1907. 
Penhallow, David Pearce. 
1894. Observations upon some noteworthy leaf variations, and their bearing 
upon paleontological evidence. — Canadian Rec Sci., vol. 9, no. 5, pp. 279-305, 
11 figs., 1905. 
1895. Notes on Tertiary and Cretaceous plants. — Abstract : Science, new s<>i\, 
vol. 23, p. 972, June 29, 1906. 
1896. A manual of the North America gymnosperms, exclusive of the ('yea- 
dales, but together with certain exotic species. Boston, (Jinn and Company, 
1907. 274 pp., 55 pis., 48 figs. 
Includes descriptions of fossil genera and species. 
1897. Contributions to the Pleistocene flora of Canada. — Am. Nat., vol. 
41, pp. 443-452, 2 figs., July, 1907. 
Includes descriptions of new species of Acer and Oleditschia. 
1898. A contribution to our knowledge of the origin and development of 
certain marsh lands on the coast of New England. — Canada, Roy. Soc, Proc. 
and Trans., 3d ser., vol. 1, sect. 4, pp. 13-55. 5 pis., 1907. 
1899. Notes on fossil woods from Texas. — Canada, Roy. Soc, Proc. and 
Trans., 3d ser., vol. 1, sect. 4, pp. 93-113, 4 pis., 1907. 
Includes a discussion of the stratigraphic position, relations, and character of the 
Yegua clays. 
1900. A report on fossil plants from the international boundary survey for 
1903-5, collected by Dr. R. A. Daly. — Canada, Roy. Soc, Proc and Trans., 3d 
ser., vol. 1, sect. 4, pp. 287-351, 9 pis., 5 figs., 1907. 
1901. A blazing beach [spontaneous combustion of gases from organic 
debris].— Pop. Sci. Monthly, vol. 70, no. 6, pp. 557-564, 1 fig., June, 1907. 
Pennsylvania, Topographic and Geologic Survey Commission. 
1902. Report 1899-1906. Harrisburg, 1906. 308 pp., 1 pi. (index map). 
Includes an account of the methods of work employed and gives records of results. 
Peppel, Samuel Vernon. 
1903. The manufacture of artificial sand stone or sand-lime brick.— Ohio 
Geol. Survey, Fourth ser., Bull. no. 5, 79 pp., 2 pis., 6 figs., 1905 [1906?]. 
The limestone resources and the lime industry in Ohio. — See Orton and 
Peppel, no. 1837. 
Perisho, Ell wood C. 
1904. The state survey of South Dakota. — Sioux City, Iowa, Acad. Sci. and 
Letters, Proc, vol. 2, pp. 79-84, 1906. 
Presents briefly in outline the work already accomplished by the state geological 
survey, the work in hand, and lines of investigation in view. 
1905. What should appear in the report of a state geologist. — Econ. Geology, 
vol. 2, no. 4, pp. 435-438, June, 1907. 
Perkins, Edwin T. 
1906. Mining and smelting at (Jranby, Missouri. — Eng. and Min. Jour., 
vol. 84, pp. 388-390, 1 fig., August 31, 1907. 
Includes notes on the geology, character, and occurrence of the zinc and lead ores. 
Perkins, George H. 
1907. Mineral resources [of Vermont]. — Vermont Geol. Survey, Fifth Rept. 
State Geol., pp. 1-62, 16 pis., 2 figs., 1906. 
Gives an account of the progress of the mineral industries of the State during the 
biennium 1905-1906. Includes notes on the occurrence of building stones, slate, and 
other products. Gives a full discussion of the occurrence, character, and origin of 
asbestos deposits. 
