505 



"First, in respect to the increase in intensity of color from the 

 north southward. Among the squirrels this increase is finely illus- 

 trated in Sciurus ///,./.*,„/,/.* and in Turn ><is strhitti s, representatives 

 of which from the southern parts of New York and Pennsylvania 

 are much more highly colored than are those from northern New 

 England and the British Provinces. Sciurus Carolinensis is per- 

 haps a still more marked example, in which the color vanes from 

 the light pure gray of the upper parts in New England specimens, 

 with a restricted' pale yellowish hrown dorsal area, to the rusty 

 gray dorsal surface of the Florida type, in which the whole upper 

 surface is usually strongly yellowish-rusty. This increase of color 

 southward is, however, still more strongly marked in the fox squir- 

 rels of the Mississippi Basin, the so-called Sciurus " ludovicianus." 



"The variations in color occurring in representatives of the 

 same species at localities differing in longitude, is well shown in 



a sullicientlv « ; : " ils ll,;lt (,,,t:lin 



along a given parallel throughout the whole breadth of the conti- 

 nent, the Sciurus If,itls„nius group being the only instance among 



in passingfroin the mo'ist, fertile prairies of the MissU-ippi \ alley 



the interior V'- I ^n-ilic coast north 



of the parallel of 40 5 . S^rnm^nl us trhlr.-, m .i;„>-otus furni>hes a 

 good illustration of the difi'erences in color that occur between 



prairies and those inhabiting- the dry. barren plains, those from 

 Illinois, Wisconsin, Minnesota and Iowa being much darker than 

 those from Western Nebraska. Western Kansas and Colorado. 

 Even specimens from Eastern Kansas are much darker than those 

 from the middle and western portions of the same State. In this 

 species the color is varied, in passing from the prairies to the 

 plains, not onh ' k ground color, but 



by the considerably greater breadth of the light spots and stripes 

 in the specimens from the plains." ^ 



"But two of the most instructive and interesting groups of the 

 Scinrtdw, in this connection, are those of which the common Sci- 

 urus Hudsouius, and Tamias quadrivittatus are respectively famil- 

 iar examples, tlx 1 " 1ki11 ^ 1 10 



