6 NORTH AMERICAN FAUNA. 



Zapus insignia to Z. hudsonius, though insignia has a different number of 

 teeth and is now considered subgeuerically distinct from the latter. 

 Under the improved methods of collecting and preserving mammals 

 now in vogue large series of well-prepared specimens have been brought 

 together during the past few years, and several new forms have been 

 described, mainly from the west and northwest. 



The following revision of the genus Zapus is based on a study of more 

 than 900 specimens, mainly in the collections of the Biological Survey of 

 the U. IS. Department of Agriculture, the U. S. National Museum, and 

 several private individuals. 1 To the custodians and owners of these 

 collections my thanks are cordially extended. For kind assistance and 

 advice my thanks are also especially due to Dr. 0. Hart Merriam, Dr. 

 T. S. Palmer, and Mr. Gerrit S. Miller, jr. Through the courtesy of 

 Mr. Miller I have had an opportunity of examining the types of Zapus 

 setcliuanus Pousargues, temporarily placed in his hands for comparison, 

 and am thus able to present a complete account of the genus, includ- 

 ing a description of this very interesting Asiatic species, the only one 

 known from the Old World. 



The National Museum collection of Zapus, though not extensive, 

 contains many specimens of unusual interest from widely separated 

 localities ; that of the Biological Survey is especially rich in western 

 specimens; and those of Miller and Bangs contain good series of east- 

 ern species. These collections, comprising many large suites of well- 

 prepared skins, nearly all accompanied by perfect skulls and by meas- 

 urements taken in the flesh, have afforded facilities for comparison never 

 before enjoyed. Much additional material is needed, however, before 

 certain questions concerning relationship and seasonal variation can 

 be satisfactorily settled. 



Distribution. Zapus is a Boreal genus, and, with the exception of a 

 single species, is confined to North America. The exact northern lim- 

 its of its range are not well known, but are indicated by specimens 

 from Hamilton Inlet, Labrador; Fort Churchill, on Hudson Bay; Fort 

 Rae, on Great Slave Lake; and the Yukon River (probably Fort Yukon, 

 just below the Arctic Circle). Southward it extends as far as Raleigh, 

 N. C.j Wheeling, W. Va,; Jackson County, Mo.; Santa Fe, N. Mex.; 

 and Kern River, California. Within the region thus roughly outlined 

 there are probably no large areas where at least one member of the 

 genus is not found. In regions where there is little or no woodland its 

 distribution is more or less local, and is confined almost exclusively to 

 the borders of streams. Of course, the arid deserts of the West do 

 not offer a congenial environment. 



'These specimens are as follows: Biological Survey, 378; U. S. National Museum, 

 85; Merriam Collection, 60; Bangs Collection, 132; Miller Collection, 200; ami a few 

 from each of the following collections, American Museum of Natural History, New 

 York; Academy of Natural Sciences, Philadelphia; Carnegie Museum, Pittshnrg, 

 Pa.; Field Columbian Museum, Chicago; and the collections of Samuel N. Rhoads 

 and Charles F. Batchelder. 



