LEl'OHlD.E-GEOailAPllICAL VARIATION. 



2G9 



with localil}' is often less strongly marked than in mnny other groups, even 

 nniung tlic Rodents. I'aUing as an illustration of this point one of our 

 widest-ranging species, the little Wood-IIarc {Lfpus sijlmtkm and its several 

 varieties), we find tliat specimens from the Carolinns, Georgia, and Florida 

 are, in the average, not much darker than those from Southern New England, 

 the difference being generally too small to give in itself a positive clue to 

 ♦he locality, as is so generally tiic case in birds, and often in other groups of 

 mammals. Indeed, specimens from the ]\Iexican provinces of Vera Cruz and 

 Yucatan are in no way positively distinguishable from those obtained about 

 Washington or in Slassachusetts. 



On comparing, however, specimens from the Atlantic coast with others 

 from the arid interior of the continent, we find the differences in color 

 resulting from the different climatic conditions of the two regions are strongly 

 marked, through the greater pallor of those inhabiting the dry plains and 

 semi-desert portions of the Great Central Plateau. The bleaching effect of 

 an arid climate is quite marked in specimens living as far east as Eastern 

 Nebraska, while the greatest degree of pallor is seen in those inhabiting tho 

 Great Colorado Desert. Again, specimens from that portion of the Pacific 

 elope north of California — a region of heavy rain-fiiU and dense forests — 

 present as dark or even a darker phase of coloration than those from the 

 Atlantic States, just as proves to be the case in the wide-ranging species of 

 the Sciurida and MuridcB. 



The same regional phases of color-variation are also illustrated by the 

 Northern Hare {Lepus americanus ax\A 'vs varietien), which ranges in a similar 

 way across the whole breadth of the continent. The increase in intensity 

 of color from the north southward is rather moro decidedly marked than in 

 L. xj/lvaficus, in both its summer and winter cond.Vions of pelage. Summer 

 specimens from New England and the Middle States are of a much stronger 

 ferruginous tint than those obtained during the same season from the arctic 

 regions. Winter specimens differ in the more nortiiern having the white 

 color of the surface so deeply invading the pelage as to wholly conceftl the 

 brown under-fur, while in those from the extreme southern limit of its range 

 the white is a mere slight superficial wash, by which the brown under-fur — 

 of a stronger tint also than in the northern specimens — is only partly con- 

 cealed, the white winter livery being often but imperfectly acquired at 

 southern localities where it is always assumed for a much shorter period. 



