MARYLAND GEOLOGICAL SURVEY 111

The extended studies which Professor Ward had made of the
Potomac, formation during the past few years had thrown much light
on the stratigraphy and fauna of the formation. In order to present
these results, Professor Ward prepared a paper entitled " The Potomac
Formation " for the report of the United States Geological Survey
for 1893-94. ¹

This was followed by a paper entitled " Some Analogies in the
Lower Cretaceous of Europe and North America, " prepared for the
report of the same survey for 1894-95. ² In this paper Professor Ward
compares the Potomac formation of Maryland and its extension with
European Lower Cretaceous formations. He figures the cycads found
in Maryland.

Some attention has been given by the survey to the collection of
fossil bones from the Potomac formation.

In 1886-87 Mr. J. B. Hatcher, working under the direction of
Professor O. C. Marsh, examined the clays in the iron mines near
Beltsville, Maryland, and found a number of vertebrate remains and
Sequoia cones. These remains were described by Professor Marsh
in a paper entitled " Notice of a New Genus of Sauropoda and other
New Dinosaurs from the Potomac Formation. "³

In October, November and December, 1887, Mr. Hatcher, under
the direction of Professor Marsh, made a further examination of the
Potomac formation between Washington and Baltimore and obtained
some additional vertebrate remains.

The stratigraphy and paleontology of the Eocene deposits of Mary-
land and Virginia were very fully investigated by Professor Clark
during the years 1888-92 for his memoir on " The Eocene Deposits
in the Middle Atlantic Slope in Delaware, Maryland and Virginia, "⁴
which appeared in 1896.

Numerous short trips have been made by members of the survey
to collect molluscan remains from the marine Cretaceous, Pamunkey

¹ Fifteenth Ann. Rept. U. S. Geol. Survey, 1895, pp. 307-397, pls. 2-4.

² Sixteenth Annual Rept. U. S. Geol. Survey, 1896, pp. 463-542, pls. 97-107.

³ Am. Jour. Sci., 3d series, vol. 35, 1888, pp. 89-94.

⁴ Bull. U. S. Geol. Survey No. 141, 1896, 167 pp., 40 pls.