1 



LErOKIDiE— LEPU8 SYLVATICUS. 



329 



Specimens from the same locality diflbr in color mainly in tlie amount 

 of black presented l»y the dorsal surface, this depending upon the relative 

 length of the black tips of the hairs. There is a slight variation also in 

 respect to the intensity of the brown of the subterminal bar. The variation 

 in color with the season is not very marked, consisting in winter specimens 

 being somewhat grayer than summer specimens. Southern specimens are 

 but little more strongly colored than northern ones, the rufous being of a 

 rather stronger tint and the black more prevalent. Those from the States 

 immediately west of the Mississippi River begin to be lighter than those from 

 the Atlantic slope. Further westward, the paleness gradually increases till 

 we reach the pale form of the arid plains. Specimens from northern locali- 

 ties, both on the Atlantic slope and in the interior, are sometimes wholly 

 without the brownish termination of the under-fur, or it is only faintly 

 developed, and confined mainly to the sides. Here it is generally, however, 

 quite strong, and is frequently quite appreciable on the middle of the dorsal 

 region. The came variation in this respect is seen both in Massachusetts and 

 western specimens; Iowa examples being not distinguishable in this respect 

 from New England ones. To the southward, however, the brownish termi- 

 nal band of the under-fur becomes more uniformly traceable, being generally 

 present in specimens from about Washington, but much stronger in those 

 from South Carolina and Florida, in which it generally forms a strong broad 

 bar, though sometimes obsolete. 



The geographical variation in color is mainly as already noticed, namely, 

 .in increasing paleness from the Mississippi westward toward the Plains, 

 where variety sylvaticus passes by insensible steps into variety nuttalli 

 (zz artemisia auct.). The specimens from Eastern Nebraska and Eiistern 

 Dakota can, in general, hardly be referable to the one form rather than to the 

 other. At the southward, the colors become slightly mor intense, but the 

 difference is by no means striking. The variation in s' with locality is 

 quite appreciable, as shown in Tables XXVII and XXVIIl, the ' gest speci- 

 mens being from the north. Washington specimens are somewhat larger than 

 those from South Carolina and Florida, while those from Massachusetts are again 

 rather larger than those from Washington ; those from Wisconsin and Iowa are 

 fully as large as New England specimens, and very much larger than Texas ones. 

 Passing further south, however, we find, contrary to what wodld be antici- 

 pated, tl- it specimens from Southern Mexir arc fully as large as those from 



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