1891.] Geology and Paleontology, 365 
the wedge-shaped and filiform leaves on the same plant was due to 
emergence and submergence, Newberry’s explanation was subsequently 
adopted by Colemans and Kickx, (Journ. Cin. Soc. Nat. Hist., Jan., 
1891.) 
Mesozoic.—Mr. Otto Lerch has made a further study of the beds 
between the Lower Cretacic, the Trinity sands of R. T. Hill, and the 
Permian, a few miles west of San Angelo, Texas, and concludes that 
they are pre-Cretacic and post-Permian, and probably may be the con- 
tinuation and southward thinning out of the Jura and Trias. (Am. 
Geol, Feb., 1891.) The Report of the Yorkshire Philosophical 
Society, 1888, contains a description of a head of Hyčodus delabechet 
from the Lower Lias of Lyme Regis, Dorsetshire, England, by A. 
Smith Woodward, in which he says that the teeth of the Wealden 
species differ so much from those of the'Liassic that possibly this later 
Mesozoic shark may eventually prove to pertain to a distinct genus. 
——In discussing the economic features of the Cretaceous rocks of 
Texas, Mr. R. T. Hill urges the necessity of recognizing the chalky 
formations of Texas as a distinct geographic region of the United 
tates. This individuality must be recognized, and the economic 
development based thereon, instead of the conditions of entirely 
different non-chalky regions, The agricultural experience of northern 
and eastern states will not apply to these soils, but we must go to the 
chalky regions of France and England, where there are analogous for- 
mations, to learn for what they are best adapted. This region is 
especially rich in mineral fertilizers, and there is a great variety an 
abundance of building material. Owing to the slightly disturbed 
conditions of the formations, the district east of the Pecos is not a 
Profitable field for the search of metallic minerals. (Report Texas 
Geol. Survey, 1889.)——A. Smith Woodward has figured and de- 
scribed two groups of teeth of the Cretaceous Selachian fish Ptycho- 
dus found in the English chalk. (Ann. Rept. Yorkshire Phil, Soc., 
1889.)——-Montagu Browne has revised the genus Dapedius,—a 
group of fossil fishes not far removed from: Lepidotide. (Trans. 
Leicester Lit. and Philos, Soc., Oct., 1890.) A study of the Shasta 
Group leads Mr, George Becker to conclude that the conditions and 
associations on the British Pacific coast appear to correspond com- 
Pletely with those in the United States so far as the Aucella beds are 
concerned, and the present indications are that all of them are to be 
regarded as equivalent to the Gault. (Bull, Am. Geol. Soc., Vol. II., 
PP. 201-208.) The newly opened oil field of Colorado is located 
m the valley of the Arkansas, between Pueblo and Cañon City. At 
