158 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
The Geological Survey of Texas, under Mr. Dumble, has already 
rendered good service to American stratigraphy and paleontology, 
and it is to he hoped that now that it is fairly started we shall soon 
have a tolerably complete and exact geology of this important part 
of North America. 
The stratigraphic series of Texas from the Carboniferous to the 
Tertiary is complete, and very important, esjoecially for correlation 
with some of the principal European epochs and formations or 
groups. It has been proved that North America, at the end of the 
Jurassic period, was a continent as it is now with the exception of 
the Gulf of Mexico, a narrow arm of which reached as far as Kansas. 
Then subsidence on a large scale began in the Missouri, Rio Grande 
del Norte, and Colorado basins, and at the beginning of the Upper 
Cretaceous epoch the sea invaded many parts of the Rocky 
Mountains. 
Table of the sedimentary strata in Texas. 
Tertiary (complete). 
Upper Cretaceous, from the Dakota to the Fox-Hills groups. 
Lower Cretaceous, from the Cyprina and Gryphaea Romer lime- 
stone to the Vola limestone. 
Jurassic, at Pike county (Arkansas), Bosque and Kent counties 
(Texas). 
Triassic, 
Dyassic (Permian). 
Carboniferous. 
Taconic (Cambrian). 
The true boundary between the Trias and Dyas may lead to 
differences of opinion, just as the Trias and Dyas of Russia is a 
subject of discussion; the Russian and Texan series of the new red 
sandstone epoch having many analogies, both lithological and 
paleontological, but it is simply a question of detailed research 
which will not affect a general table of the sedimentary strata. 
