40. THAMNOPHIS 851 
V ariation.—Eight specimens have the loreal 1—1 in all. 
The preoculars are 1—1 in all. The postoculars are 3—3 
in two, 3—4 in two, and 4—4 in two. The temporals are 
1+3—1+3 in four, 1+2—1+2 in three, and 1+3—2+3 in 
one. The supralabials are 8—8 in twelve, 7—8 in one. The 
infralabials are 10—11 in four, and 10—10 in two. The scale 
rows are 21—19—17 in ten, 21—21—17 in one, 23—23— 
17 in one, and 21—26 in one. The gastrosteges vary in num- 
ber from 149 to 162, males having from 157 to 162, females 
from 149 to 159; the average in six males is 160.5, in eight 
females, 154.9. The urosteges vary from 63 to 79, males 
having from 77 to 79, females from 63 to 67; the average 
in two males is 78, in four females, 64.7. 
Distribution —This_ garter-snake ranges north from 
Mexico into the United States. It has been found in Sono- 
ra and Arizona, and in California along the Colorado 
River. It extends its range through Texas to Oklahoma. 
The details of its distribution through this area are yet to 
be worked out. As regards Arizona, authentic specimens 
have been recorded from the vicinity of Tucson and Yuma. 
At Yuma it occurs on both banks of the Colorado River, and 
the westernmost limits of its known range are along the 
banks of this river from Yuma north to Riverside Moun- 
tain in Riverside County, California. 
We have examined specimens from Fairbank, Cochise 
County, Tucson, Pima County, Gila Bend, Maricopa Coun- 
ty, Yuma, Yuma County, Arizona, Colorado River eight 
miles east from Picacho, Imperial County, California, and 
Riverside Mountain, Colorado River, Riverside County, 
California. 
Ruthven examined other specimens with definite locali- 
ties as follows: Fort Yuma, Imperial County, California; 
Tucson, Arizona; White Horse Springs and Fort Supply, 
