82 BIBLIOGRAPHY AND INDEX OF N. A. GEOLOGY, [hull. 146. 
53G White (Charles Henry ). An examination into the nature of PaUeo- 
trochis. 
Elisha Mitchell Sci. Soc, Jour. 1894, part ii, pp. 50-66, with plate. 
Reviews Emmons's description of Palaeotrochis and of the strata in 
.which it occurs in North Carolina. Discusses the evidences of its con- 
cretionary and of its organic origin. 
537 White (David). The Pottsville series along New River, West 
Virginia. 
Geol. Soc. Am., Bull., vol. vi, pp. 305-320. 
Discusses the use of the term Pottsville. Describes the differentia- 
tion of floras in Pottsville time and the stratigraphic relations of the 
series, giving vertical sections oi the Piney Creek and Nuttall and Hawks 
Nest sections. Discusses the paleontologic relations of the beds and 
gives lists of fossils from various horizons. 
538 Whiteaves (J. F.). Revision of the fauna of the Guelph forma- 
tion of Ontario, with descriptions of a few new species. 
Geol. Surv. of Can., Paleozoic Fossils, vol. iii, part ii, pp. 45-109, pis. 
ix-xv. 
Mentions the species found in this formation in Ontario, with notes 
on their occurrence in other formations. Describes several new species. 
539 Systematic list, with references, of the fossils of the Hudson 
River or Cincinnati formation at Stony Mountain, Manitoba. 
Canada Geol. Surv., Paleozoic Fossils, vol. iii, part ii, pp. 111-128. 
Gives a brief sketch of the discovery of Hudson Paver strata at this 
locality and a list of fossils that have been collected. 
540 Williams (Edward H.). Notes on the southern ice limit in eastern 
Pennsylvania. 
Am. Jour. Sci., 3d ser., vol. xlix, pp. 174-185. 
Presents a map showing the boundaries recoguized during the pre- 
vious year. Discusses the evidences of the character of the deposits 
made during the advance and retreat of the ice sheet. Describes the 
distribution and character of the glacial deposits of the region, the influ- 
ence of the ridges on the ice advance, and the glacial gravels of the 
Juniata Valley. 
541 Williams (George Huntington). General relations of the granitic 
rocks in the middle Atlantic Piedmont plateau. 
U. S. Geol. Surv., 15th Ann. Rept., pp. 657-684, pis. xxvii-xxxv. 
Discusses the criteria for the recognition of ancient plutonic rocks in 
highly metamorphosed terranes, the distribution and age of the Appa- 
lachian igneous granites, and the gradations of Maryland granites. 
Discusses the origin of Maryland pegmatites. 
542 Williams (Henry Shaler). On the recurrence of Devonian fossils 
in strata of Carboniferous age. 
Am. Jour. Sci., 3d ser., vol. xlix, pp. 94-101. 
Describes the geologic relations and age of the strata near Batesviile, 
Ark., and remarks on the occurrence of Devonian fossils in rocks that 
belong to the Carboniferous. Compares the Batesviile fauna with the 
Devonian faunas of Eureka, Nev., Shasta County, Cal., and of the Mis- 
sissippi Valley. Describes the differences in the succession of the Devo- 
nian faunas of the West and of the Appalachian province. 
