102 BULLETIN 17 5, UNITED STATES NATIONAL MUSEUM 



any, geographic significance, the average number remaining fairly 

 constant throughout the range of the form. Whatever geographic 

 trend is present is toward a decrease in the number of spots from south 

 to north, as might be expected in correlation with the dwarfing that 

 occurs. However, the decrease in the number of spots appears to be 

 more marked to the east than to the west, while the reverse is true of 

 most of the scale characters. 



Sexual variation evidently exists in many of the scale characters. 

 The variations that occur may be summarized as follows: Dorsal scale 



25 



34 



49 



39 



31 



70 

 68 

 66 

 64 

 62 

 60 

 58 

 56 



54 



52 

 90 

 48 

 46 



Region No. 1 2 3 4 5 6 



Figure 53.— Geographic variation in number of caudals in Pituophis sayi sai/i. 



formula vaiying from 25-28-23 to 31-37-27 in males, from 23-29-21 

 to 35-37-27 in females; ventrals 212 to 236 (average 222.9) in males, 

 216 to 244 (average 227.2) in females; caudals 49 to 67 (average 58.8) 

 in males, 47 to 65 (average 53.2) in females; supralabials average 8.5 

 in males, 8.4 in females; infralabials average 12.4 in males, 12.3 in 

 females; preocidars average 1.3 in males, 1.4 in females; postoculars 

 average 3.5 in males, 3.4 in females; body spots average 51.2 in males, 

 51.0 in females; tail spots average 13.6 in males, 12.6 m females; 

 proportionate tail length varies from 0.104 to 0.145 (average 0.125) 

 in males and from 0.100 to 0.140 (average 0.117) in females. In the 



