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ON THE EXTINCT ANIMALS OF NORTH AMERICA. 
By Professor WILLIAM HENRY FLOWER, F.R.S. 
[PLATE CXXXVIIL] 
F EW branches of knowledge have received greater accessions 
during the last few years than that of the past history of 
the living creatures which have peopled the earth. 
I propose in the present instance to call attention to some 
of the results that have been achieved, mostly within the last 
four or five years, by a small but energetic band of explorers 
upon a limited part of the earth’s surface ; results the greatness 
of which already is only equalled by the promise they give of 
future still more important extensions of knowledge. 
It is mainly through the agency of the admirably conducted 
geological and geographical surveys of the Western Territories, 
made by the United States Government, under the direction of 
Dr. F. V. Hayden, that the subjects to which I shall refer have 
been brought to light ; surveys which are giving to the world, 
in an excellent series of publications, rich funds of information 
upon the physical geography, mineralogy, geology, palaeontology, 
zoology, and botany of that hitherto little known but most 
remarkable region of the earth embracing and bordering the 
great range of the Rocky Mountains. For the special know- 
ledge which we in England possess of the vertebrate fossils 
which have been discovered by these surveys, we are greatly 
indebted to the excellent descriptions of Professor Joseph Leidy - 
of Philadelphia, who in two large and beautifully illustrated 
volumes* has given the results of his investigations upon them. 
More recently two other naturalists, Professor E. D. Cope of 
* 11 Extinct Mammalian Fauna of Dakota and Nebraska, with a Synopsis 
of the Mammalian Remains of North America,” e Journ. Acad. Nat. Science/ 
Philadelphia, 1869 ; and u Contributions to the Extinct Vertebrate Fauna 
of the Western Territories,” ‘ Report of the U. S. Geological Survey of the 
Territories,’ Washington, 1873. 
