15 



It is now generally admitted that the upper strata of the limestone (mostly 

 magnesian) underlying the Cretaceous, west of the Missouri River, belongs to 

 the IiOwer Permian, though a large number of species of mollusks of the Car- 

 boniferous formations are still mixed in these strata, with predominant and 

 characteristic species of the Permian, in such a way that this limestone is 

 often called by the name of Per?no-carboniferous. Until recently, I had 

 never been able to see any trace of vegetable remains from this formation, 

 and thus to know what the fossil plants might indicate in relation to the evi- 

 dence furnished by animal paleontology. In the explorations of Dr. Hayden 

 of 1873, however, Dr. A. C. Peale discovered, in strata referred by him 

 either to the Carboniferous or the Permian, a number of well-preserved 

 branches or stems of Catamites, whose identification proves for the formation 

 whence they are derived the same intermixture of characters referable to both 

 the Permian and the Carboniferous. A large number of these specimens rep- 

 resent Catamites approxhnatus, Brgt., a species which as yet has been consid- 

 ered as belonging exclusively to the Carboniferous, and which in this case is 

 distinctly characterized by its very thick bark. The outer coating, which is 

 generally a compound of carbonaceous layers, is in these specimens petrified 

 like the internal woody cylinder, but destroyed in some parts of the stems, 

 and in that way the different characters of both the internal cylinder and the 

 bark are exposed to view. The other specimens are well-preserved frag- 

 ments of Catamites gigas, Brgt., which has been formerly considered by 

 Brongniart and Unger as an Upper Carboniferous species, but which now is 

 admitted as characteristic of the Lower Permian. After indicating its habitat 

 in the red sandstone of Alsatia, of Wettaravia, with specimens of IVatchia in 

 the Permian of Russia, &c, Schimper, in his Vegetable Paleontology, (1869,) 

 adds that this species has never been found in a productive Carboniferous for- 

 mation, &c. These specimens were all obtained from the same locality 

 Eagle River, near Holy-Cross Mountain, Colorado, together with many frag- 

 ments of undeterminable Stigmaria and one of an Asterophyllites. This 

 coincidence in the data furnished by animal and vegetable paleontology proves 

 that the end of the Paleozoic times in our American geology is marked, from 

 the Mississippi River to the Rocky Mountains, by the Upper Carboniferous, 

 already modified by the first traces of Permian life. 



The formation of the Dakota group, corresponding to the Upper Creta- 

 ceous of Europe, is now recognized to be in immediate superposition to this 



