40. THAMNOPHIS 811 



Variation. Twenty-one specimens from Arizona have 

 loreals 1 1 in all. The preoculars are 1 1 in all, but 

 one, which has 1 2. The postoculars are 3 3 in all but 

 three which have 3 4-. The temporals are 1+2 1+2 in 

 fourteen, 1+2 1+3 in three, 1+3 1+3 in three, and 

 2+3 2+3 in one. The supralabials are 8 8 in twenty, 

 and 8 9 in one. The infralabials are 10 10 in seven- 

 teen, 11 11 in two, 10 11 in one, and 9 10 in one. 

 The scale-rows are 19 19 17 in all but one, which has 

 21 19 17. The gastrosteges vary in number from 164- 

 to 175, males having from 166 to 175, females from 164 to 

 171j the average in thirteen males is 170.6, in seven 

 females, 168. The urosteges vary from 77 to 97, males 

 having from 85 to 97, females from 77 to 88 ; the average 

 in twelve males is 91.7, in six females, 83.5. 



Distribution. This snake occurs in the United States 

 in Arizona, New Mexico and western Texas. Thence it 

 ranges south through Mexico to Guatemala. In Arizona 

 it has been found in the plateau region and about the foot- 

 hills of various mountain groups. Ruthven has recorded it 

 from Fort Apache, Fort Huachuca, White River Canyon, 

 Sabino Canyon, and Fort Whipple, Arizona. We have 

 examined specimens from Maricopa (Cave Creek), Coco- 

 nino (Oak Creek), Pima (Catalina Mountains, 18 miles 

 north from Tucson, Sabino Canyon, Catalina Mountains, 

 Sawmill Canyon, Santa Rita Mountains), and Santa Cruz 

 (canyon between Madera and Agua Caliente canyons, Cot- 

 tonwood Canyon, Agua Caliente Canyon, Gardner Canyon, 

 and Stetson's Dam, all in the Santa Rita Mountains) 

 counties, Arizona. Dr. Stone has recorded this species from 

 Sycamore Canyon, Baboquivari Mountains, Arizona; and 

 Dr. Stejneger from Fort Huachuca, Arizona. 



