VARIATIONS OF GARTER-SNAKES. 



183 



that it is frequently impossible to refer a specimen definitely to 

 either form. Nevertheless, wliile its range is not distinct from that 



Percentage of 

 specimeiLS. 



.98 

 .82 

 .66 

 .50 

 .3 4 

 .18 



•°^11-11 11-10 10-10 10-9 9-3 8-8 



Infralabials. 



Fig. 80.— Vakiation in the number of infralabials in 113 specimens of Tuamnophis sirtalis 

 from southeastern michigan. 



of sirtalis, it must be pointed out that the majority of the specimens 

 examined hail from northeastern United Sta-tes (east of Ohio and 



170 

 16 9 

 154 

 146 

 138 



Illinois. Southern Northern Indiana. Ohio. Florida. Maryland. Massa- Khode 

 Michigan. Michigan. chusetts. Island ' 



Fig. 81.— Diagram showing the variation in the number of ventral scutes in Thamnophis 



sirtalis. 



north of North Carolina), those from outside of tliis region being but 

 scattered records. 



