48 THE AMERICAN NATURALIST. (VoL. XXXVI. 
Upon exhibiting my photographs to Mr. Gerret S. Miller, Jr., 
of the Mammal Department of the United States National 
Museum at Washington, D.C., he at once pronounced them to 
be specimens of the kangaroo rat described by Dr. J. A. Allen 
as Perodipus richardsoni, a species, so far as at present known, 
confined to Indian Territory, Kansas, and Oklahoma. 
During the last sixteen or seventeen years the number of 
new North American species of jumping mice and kangaroo rats 
described by our mammalogists has been something phenomenal. 



Fic. 1.—P. ip ithardsoni(Allen). ĝ (asleep). Less than 14 nat. size. 
Photographed from life by the author. 
Other genera have been similarly increased. When the United 
States National Museum published its provisional list of mam- 
mals of North America in 1884 (Proc. U. S. Nat. Mus., Vol. VII, 
Appendix, p. 585), there were but two subspecies of Dipodomys 
recorded, and but one species of Zapus. If we turn now to 
the excellent volume published by Mr. D. G. Elliot, curator of 
the Department of Mammals of the Field Columbian Museum 
of Chicago (Zoól. Ser, Vol. II, Chicago, 1901), entitled A 
Synopsis of the Mammals of North America and the Adjacent 
Seas, we find that there was recorded at the time of the 
issuance of that book no less than 23 kangaroo rats and 20 

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