40. THAMNOPHIS 857 
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 254 339 347 389 408 428 
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% 3 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 11%¢; 8—9 in two, or 11%; 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 177, 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, 
Ved « 
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 
