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1887] Mesozoic and Cenozoic of North America, 445 
THE MESOZOIC AND CÆNOZOIC REALMS OF 
THE INTERIOR OF NORTH AMERICA. 
BY E. D. COPE.* 
N the following pages all the sources of information on the 
subject in hand have been Jaid under contribution. Chief 
among these are the reports of the United States geological 
survey of the Territories under F. V. Hayden, the United States 
geological survey of the fortieth parallel under Clarence King, 
and the United States geological survey west of the one hun- 
dredth meridian under Captain G. M. Wheeler, United States 
Engineers. The association of the author with the first and last 
named of these surveys ia the field, and the examination of large 
collections of vertebrate fossils made in the region reported on, 
furnish the opportunities in his Possession. 
The author does not recognize in the following pages a Qua- 
ternary division of geological time, but regards the present period 
as a continuation of the Cenozoic or Tertiary Realm, including 
all after the beginning of the glacial age under the name Plis- 
tocene, 
MESOZOIC REALM. 
This system is distinguished from the Palzozoic in, North 
America, as to the Vertebrata, as follows: 
Presence of Reptilia Dinosauria, Ichthyopterygia, Sauropte- 
rygia ? Pterosauria, Testudinata, and Lacertilia; presence of Mam- 
malia. Absence of Tunicata Antiarcha, Agnatha Arrhina, and 
Diplorhina,? of Pisces Placoganoidei, of Batrachia Ganocephala 
? Rhachitomi and Embolomeri,3 and of Reptilia Theromorpha.* 
From the Cenozoic system the Mesozoic differs in the presence 
of Reptilia Dinosauria, Sauropterygia, Ichthyopterygia; of Mam- 
malia Marsupialia Multituberculata ;5 and in the absence of Pisces 
Actinopteri, é Nematognathi, and Plectospondyli; of Aves Inses- 
sores, and Mammalia Diplarthra’ and Rodentia. 
* Read before the American Committee of the International Geological Congress 
at its meeting at Albany, April 6, 1887. The writer, previous to the adoption of the 
report of the proceedings of the committee for the previous year," objected to the 
of the word “ group,” as proposed by the Congress of Berlin, for the 
division of geological formations of first rank, and proposed to substitute the word 
“ realm” therefor; eg., the Archzan, Palzozoic, Mesozoic, and Cenozoic Realms, . 
