VARIATIONS OF GARTEK-SN AKi:S. 



117 



differences in color have been ()l)serve(l which are evidently geo- 

 graphic.) 



If the data plotted can be depended upon to reveal the actual 

 state of variation, the form may thvis be divided into two sections 

 upon the basis of the scutellation and tail length, i. e., a trans- 

 Allegheny section characterized by a larger number of ventral iScutes, 

 a shorter tail and fewer subcaudal scutes, and a coastal plain section 

 characterized by a fewer number of ventral plates, a longer tail and 

 more subcaudal scutes. 



143 



135 

 121 

 119 

 111 

 103 

 95 

 81 



Fig. 50.— DiAdKAM .siiMWiNi; the variation in tiik numiier of subcaudal scutes in ThamnoI'iiis 



SAUKlTUS. 



Affinities. — The position of the lateral stripe (on the third and 

 fourth rows) and the long tail justifies us in placing sauritus in the 

 same group with sackeni and jjroximus. As has been shown, it meets 

 the range of sackeni in the latitude of northern Plorida and that of 

 proximus along the eastern boundary of Illinois and in western Ken- 

 tucky, Tennessee, and Mississippi. Specimens from the intermediate 

 region along the conunon boundaries of the three forms remain to be 

 examined, but I Ixdieve that there can be no doubt that sauritus 

 intergrades perfectly with both sackeni and proximus. 

 33553— Bull. 61—08 9 



