SNAKES OF THE GENUS PITUOPHIS 



189 



as well as the proportionate tail length (fig. 83), are so constant 

 throughout the range that no significant variations can be discovered. 

 A slight tendency toward a general increase in the number of both 

 body and tail spots from north to south appears to exist (fig. 84). 



The sexual variation evident from a study of the form may be 

 summarized as follows: Dorsal scale formula varies from 29-29-21 to 



5 77 55 



11 



33-37-25 

 31-37-25 

 33-35-25 



32-35-25 

 31-35-25 

 31-35-23 



29-35-23 

 31-34-25 

 29-34-24 

 33-33-25 

 31-33-25 

 31-33-23 

 31-33-21 

 30-33-25 

 30-33-24 

 30-33-23 

 29-33-25 

 29-33-24 

 29-33-23 

 28-33-24 

 25-33-25 

 28-32-22 

 31-31-23 

 29-31-25 

 29-31-23 

 29-31-22 

 27-31-23 

 29-29-21 



Region Mo. 123456 7 8 



Figure 79.— Geographic variation in number of scale rows in Pituophis catenifer annedens. 



31-35-25 in males, from 29-31-22 to 33-37-25 in females; ventrals 

 from 210 to 253 (average 227.8) in males, 224 to 241 (average 232.7) 

 in females; caudals 60 to 84 (average 76.4) in males, 62 to 82 (average 

 70.0) in females; supralabials, infralabials, preoculars, and postoculars 

 all slightly higher on the average in females than in males; body spots 

 average 75.8 in males, 75.0 in females; tail spots average 24.8 in males, 



