LE DIRORIAG 
With this number the Journal of Geology begins the publication 
of the Correlation Papers which were presented to Section E of the 
American Association for the Advancement of Science in Baltimore, 
in December, 1908. ‘The first articles are those by President Van 
Hise and Professor Adams, and deal with the principles of pre- 
Cambrian geology. Later papers will deal with successive periods or 
groups of periods, and will appear in chronological order in successive 
numbers of the Journal, as follows: C. D. Walcott: ‘Evolution of 
Early Paleozoic Faunas in Relation to Their Environment;” A. W. 
Grabau: “ Physical and Faunal Evolution of North America in the 
Late Ordovician, Silurian, and Devonian Time;” Stuart Weller: 
Correlation of Middle and Upper Devonian and Mississippian 
Faunas of North America;”’ G. H. Girty: ‘Physical and Faunal 
Changes of Pennsylvanian and Permian in North America;’’ David 
White: “The Upper Paleozoic Floras, Their Succession and Range;”’ 
S. W. Williston: ‘“ Environmental Relations of the Early Vertebrates;”’ 
T. W. Stanton: ‘Succession and Distribution of Later Mesozoic 
Invertebrate Faunas;’’ W. H. Dall: ‘Conditions Governing the 
Evolution and Distribution of Tertiary Faunas;” Ralph Amold: 
“Environment of the Tertiary Faunas of the Pacific Coast;” F. H. 
Knowlton: ‘Succession and Range of Mesozoic and Tertiary 
Floras;’”’ H. F. Osborn: ‘ Environment and Relations of the Tertiary 
Mammalia;” Rollin D. Salisbury: ‘‘ Physical Geography of the Pleisto- 
cene with Special Reference to Conditions Bearing on Correlation;”’ 
D. T. MacDougal: ‘Relation of Plants to Climate with Special 
Reference to Pleistocene Conditions;’”’ T. C. Chamberlin: ‘ Dias- 
trophism as the Ultimate Basis of Correlation.” 
With these papers, several of Mr. Willis’ maps of the North Ameri- 
can continent, at various stages of its history, will be published, together 
with some explanatory notes. It is hoped that these articles will 
prove to be of general interest to readers of the Journal, as they were 
to those who heard them in Baltimore. It is possible that the several 
articles will be issued in book form, after the series is completed. 
Re Das 
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