40. THAMNOPHIS 



unicolor above in adults, mottled in young. Each superior 

 and inferior labial with a marginal patch of brown with a 

 darker border. No postoral crescents. Throat yellow. Lower 

 surfaces greenish or bluish gray, with numerous small black- 

 ish spots, gastrosteges sometimes with basal dark markings 

 which may form more or less definite dark stripes. 



Length to anus_._ ___254 339 3+7 389 408 428 



Length of taiL_ _ , 69 107 110 120 125 146 



Variation. — In eighteen specimens from Arizona the 

 loreals are 1 — 1 in seventeen and 1 — 2 in one. The preocu- 

 lars are 2 — 2 in sixteen, or 89%; 2 — 3 in two, or 11%. 

 The postoculars are 3 — 3 in ten, or 56%'; and 3—4 in 

 eight, or 44-%. The temporals are 1 + 1 — 1 + 1 in nine, or 

 50%; 1 + 1— 1+2 in eight, or 44%; and 1+2— 2+2 in one, 

 or 6%. The supralabials are 8 — 8 in thirteen, or 72%; 

 7 — 8 in two, or 1 1 Si ; 8 — 9 in two, or 1 1 % ; and 7 — 7 in 

 one, or 6%. The infralabials are 10 — 10 in nine, or 53%; 

 9 — 10 in four, or 24%; and 9 — 9 in four, or 24%. The 

 scale rows are 21 — 19 — 17 in all. The gastrosteges vary 

 in number from 161 to I 77, males having from 165 to 177, 

 females from 161 to 170; the average in eleven males is 

 171.3, in seven females, 164.9. The urosteges vary from 

 69 to 87, males having from 80 to 87, females from 69 to 

 82; the average in eleven males is 84.2, in seven females, 

 73.9. 



Distribution. — This species occurs in the northern part 

 of the Mexican plateau south to Coahuila and Durango and 

 north to portions of southwestern New Mexico and southern 

 and central Arizona. The original Arizonan specimen was 

 labeled merely "Southern Arizona," and no definite locality 

 in that state was recorded until our specimens were secured 



