330 BIBLIOGRAPHY AND CARTOGRAPHY

KLITTKE, M. Entwicklung, Organisation und Leitstungen der
geologische Landesaufnahmen in den Vereinigten Staaten von Nord
Amerika.

Zeit. f. prak. Geol., 1896, pp. 209-213, 289-352.
The history of Maryland surveys is given on pp. 312-313.

KNOWLTON, F. H. American Amber-producing Tree.

Science, n. s., vol. iii, 1896, pp. 582-584.

A description of material found by Mr. Arthur Bibbins at Cape Sable, Md.

MARCOU, JULES. The Jura in the United States.

Science, n. s., vol. iv, 1896, pp. 945-947.

Regards the Potomac formation as Jurassic and refers to Tyson's and Marsh's work.

MARSH, O. C. The Dinosaurs of North America.

16th Ann. Rept. U. S. Geol. Surv., 1894-95, part i, Washington, 1896, pp.
195-244, plates ii-lxxxv.

Many of the forms described were found in Maryland, especially in the Potomac
formation.

———— The Jurassic Formation on the Atlantic Coast.
Science, n. s., vol. iv, 1896, pp. 805-816.
Amer. Jour. Sci., 4th ser., vol. ii, 1896, pp. 433-447.

The author claims that the vertebrates indicate the Jurassic age of the Potomac
formation.

MARYLAND STATE WEATHER SERVICE. The Climatology and
Physical Features of Maryland.

Second Biennial Report of the Maryland State Weather Service for the
3^rears 1894 and 1895. Baltimore, 1896.

PHILLIPS, J. A., and LOUIS, HENRY. A Treatise on Ore Deposits.
8vo. 943 pp. Macmillan, 1896.

References to Maryland gold (785), iron (826), chrome (828).

PHILLIPS, P. LEE. Virginia Cartography—a Bibliographical De-
scription.

Smithsonian Misc. Coll. No. 1039, vol. xxxviii, Washington, 1896, 8vo,
85 pp.

Contains historical remarks on many of the old maps covering the area of Maryland.

SCHOTT, C. A. The Secular Variation in Direction and Intensity,
of the Earth's Magnetic Force in the United States and in some
adjacent foreign countries.

Rept. Supt. U. S. Coast and Geodetic Survey for 1895, Washington, 1896,
pt. ii, appendix 1, pp. 167-320.

This is the latest of a series of papers on magnetism which have appeared almost
annually in the publications of the Survey. As the subject is somewhat removed from