172 General Notes. [ Feb. 
there has been some error of observation. It must be said, how- 
ever, that the conclusions of Mr. Dawson have been confirmed by 
two other competent members of the survey.—E&. D. Cope. 
The Cross-Timbers of Texas.—The paper recently read before 
the Washington Philosophical Society on “ The Cross-Timbers 
of Texas,” by Mr. Robert T. Hill, who is a native of that State, 
and now connected with the United States Geological Survey, 
gives some interesting data about that hitherto little studied 
region. The article demonstrated that these two belts of anoma- 
lous timber, instead of representing quaternary or tertiary basins, 
are merely the detritus of outcrops of arenaceous strata, those of 
the eastern member being probably of the age of Dakota sand- 
stone, and the western of a sandy group at the base of the entire 
cretaceous series, part of which are of undetermined Mesozoic, 
and are given the name of “ Dinosaur Sands” by Mr. Hill, while 
part of them are of undoubted Carboniferous age. He further- 
more shows that the topography of the entire central region is 
the result of extensive denudation, whereby the members of the 
geologic series, from the marine tertiary to the Carboniferous 
coal-measures, are successively exposed along the line of the 
Texas Pacific Railroad, from Elmo to Millsap. The most inter- 
esting feature of Mr. Hill’s paper, however, is that he demon- 
strates, the existence of a marine group of the Cretaceous in 
Texas lower than any heretofore recognized in America, and 
completely clears up, by methods of stratagraphic paleontology, 
the vagueness that has hitherto accompanied our knowledge of 
that region. The paleontological results of the work are also 
very ee and will be studied and presented by Dr. C. A. 
White 
MINERALOGY AND PETROGRAPHY.« 
Rosenbusch’s ‘‘Massige Gesteine.”—It is rarely that the re- 
vision of a standard work in any branch of science is followed 
with so much interest as has been the case with Professor Rosen- 
busch’s “ Mikroskopische Physiographie der Mineralien und Ges- 
teine,” the first part of the second volume?’ of which has recently 
been issued. When the first edition of this classical work a 
peared (1877) the study of rocks by means of the microscope _ 
had but just begun to take its place as an independent science, 
oeae new methods of investigation, new apparatus for these 
nvestigations, and new modes of reasoning by which the truths 
BAAT ne by them could be made use of in the elucidation of 
many obscure probie in the broader science of geology. I 
is not surprising, then, that as petrography increased its store of 
: + Edited by Dr. W. S. Baviey, Madison, Wisconsin. 
handiong (E Koch). t Abt., Stuttgart, 1 1886. E. Schweizer bart’sche Verlags- 
