MARYLAND GEOLOGICAL SURVEY 261

CONRAD, T. A. Observations on the Eocene formation of the
United States, with descriptions of species of Shells, &c., occurring
in it.

Amer. Jour. Sci., 2nd ser., vol. i, 1846, pp. 209-221, 395-405; plate i, ii, iii, iv.

Descriptions of species of Pholas, Pholadomya and Panopaea from Piscataway, Md.

Descriptions of species of Crassatella and Corbula from Piscataway, Upper Marl-
borough and the post Pliocene of Maryland.

LOCKE, JOHN. Observations made in the years 1838, '39, '40, '41,
'42, and '43 to determine the Magnetical Dip and Intensity of Mag-
netical Force in several parts of the United States. (Head April 19,
1844.)

Trans. Amer. Phil. Soc., vol. ix, 1846, pp. 283-328.

Determines these constants at Baltimore, Washington, Cumberland and Emmits-
burg.

SABINE, E. Contributions to Terrestrial Magnetism No. VII Con-
taining a Magnetic Survey of a Considerable portion of the North
American Continent.

Phil. Trans. Roy. Soc. London, vol. cxxxvi, pt. i, 1846, pp. 237-336.

1847.

CONRAD, T. A. Observations on the Eocene formation and descrip-
tions of one hundred and five new fossils of that period from the
vicinity of Vicksburg, Mississippi. With appendix.

Proc. Acad. Nat. Sci., Phila., vol. iii, 1847, pp. 280-299.

The author regards the Fort Washington, Plscataway and Upper Marlboro deposits
as lower Eocene. (See Conrad, 1848.)

HALL, JAMES. Paleontology, Vol. I. Geological Survey of New
York. Albany, 1847. Containing descriptions of organic remains
of the lower division of the New York system.

Description and figures of numerous forms from Cumberland and vicinity.

KNIGHT, JONATHAN. Letter to T. Parkin Scott—advantages of
the several termini on the Ohio river for the B. & O. R. R. 8vo.
pp. 29.

LOOMIS, E. Notice of some recent Additions to our knowledge of
the Magnetism of the United States and its Vicinity.
Amer. Jour. Sci., 2nd ser., vol. iv, 1847, pp. 192-198.
Gives determinations by Prof. Locke.

1848.

CONRAD, T. A. Observations on the Eocene Formation and de-
scriptions of 105 new fossils of that period from the vicinity of Vicks-