110 HISTORICAL SKETCH

In October, 1886, he visited Baltimore to observe outcrops and collect
plants as above mentioned, and thence accompanied Professor McGee
on a trip to the head of Chesapeake Bay. On this trip plant collec-
tions were made in the Potomac and overlying marine Cretaceous. In
1886-87 Professor Ward prepared a paper on " The Geographical
Distribution of Fossil Plants, "¹ in which those from Maryland are
referred to.

In 1888 Professor Ward presented before the National Academy of
Sciences the " Evidence of Fossil Plants as to the Age of the Potomac
Formation. "²

In 1888-89 Mr. F. H. Knowlton, under the direction of Professor
Ward, prepared a report on " Fossil Wood and Lignite of the Poto-
mac Formation, " collected at various points in the District of Colum-
bia and adjacent portions of Maryland. This was published as a
Bulletin of the Survey, ³ and as a brief preliminary report in the Amer-
ican Geologist. "

At various times during the next two years Professor Ward made a
number of trips to localities in the Potomac formation area in Vir-
ginia and Maryland, and in November and December, 1891, accom-
panied by Mr. David White, collected Potomac fossil plants from the
Potomac formation east of Washington. In the spring of 1892,
accompanied by Mr. White, he made an extensive examination of
many localities in the Potomac area of Maryland and northward.

In the latter part of 1893 Professor Ward, accompanied by Pro-
fessor W. M. Fontaine, examined representative exposures about Wash-
ington, Baltimore and Fredericksburg, and on the banks of the Severn,
Potomac and Rappahannock rivers. In March, 1894, Professor Ward
made a short trip to examine the localities at which many cycadean
remains had been discovered by Mr. Bibbins. An account of these
remains was published in a paper entitled " Recent Discoveries of
Cycadean Trunks in the Potomac Formation of Maryland. "⁵

¹ Eighth Ann. Rept. U. S. Geol. Survey, part ii, 1889, pp. 870-872.

² Am. Jour. Sci., 3d series, vol. 36, pp. 119-131.

³ Bull. U. S. Geol. Surrey No. 56, 1889, 72 pp., 7 pls.

⁴ Am. Geologist, vol. iii, 1889, pp. 99-106.

⁵ Bull. Torrey Bot. Club, vol. xxi, 1894, pp. 291-299..