MARYLAND GEOLOGICAL SURVEY 331

the aim of the bibliography, the more important papers are only appended. They ap-
peared in Report for 1854, Appendix 43, pp. 143-145; Report for 1856, Appendix 28-30,
32-33, pp. 209-249; Report for 1858, Appendix 24, pp. 191-192; Report for 1859, Appendix
24, pp. 296-305; Report for 1861, Appendix 22, pp. 242-251; Report for 1862, Appendix 19,
pp. 212-229; Report for 1874, Appendix 8, pp. 72-108; Report for 1885, Appendix 6, pp.
129-274; Report for 1886, Appendix 12, pp. 291-407; Report for 1888, Appendix 7, pp.
177-312; Report for 1890, pp. 274-275.

VAN DER HOOGT, CORNELIUS, Bureau of Immigration. State of
Maryland. 1896.

Brief popular summary of the natural resources of Maryland.

VAN HISE, C. R. Principles of North American Pre-Cambrian
Geology.

16th Ann. Rept. U. S. Geol. Surv., 1894-95, part i, Washington, 1896, pp.
581-843, 2 maps and illustrations.

Gives a few incidental references to the Maryland pre-cambrian.

WALCOTT, C. D. The Cambrian Rocks of Pennsylvania.

Bull. U. S. Geol. Surv. No. 134, 1896.
House Misc. Doc., 54th Cong., 2nd sess., vol. —, No. 24.

Contains Incidental reference to his work with Keith in Frederick county and also
to the southern continuation of Pennsylvania formations.

WARD, L. F. Some Analogies in the Lower Cretaceous of Europe
and North America.

16th Ann. Rept. U. S. Geol. Surv., 1894-95, part i, Washington, 1896, pp.
463-542, plates xcvii-cvii.

A general discussion of the character and limits of the Potomac, especially of the
Middle Atlantic Slope in comparison with the Wealden.

———— Fossil Plants of the Wealden.

Science, n. s., vol. iii, 1896, pp. 869-876.

Refers briefly to the cycads from the Potomac of Maryland.

———— Age of the Island Series.

Science, n. s., vol. iv, 1896, pp. 757-760.
Refers briefly to the Potomac group of Maryland.

WHITNEY, MILTON. Texture of Some Important Soil Formations.
U. S. Dept. Agri., Div. Agri. Soils, Bull. No. 5, Washington, 1890. Illus-
trated, 23 pp., plates 35.

Six types taken from various portions of Maryland.

WILLIS, BAILEY. The Northern Appalachians.

The Physiography of the United States.

Geographic Monographs I, American Book Co., 169 pp., 1896.

A study of the present topography and its origin.