13. COLUBRID.^ 



tals. Anterior and posterior nasals distinct. Loreal a little 

 longer than high. One preocular. Two postoculars. Tem- 

 porals normally two followed by three. Seven or rarely 

 eight superior and nine, or sometimes 10 or 11, inferior 

 labials J fourth, fifth and sixth superior, and fourth and fifth 

 inferior largest} third and fourth superior reaching eye. 

 Genials in two pairs, anterior much larger than posterior. 

 Scales smooth, thin, imbricate, in 23 or sometimes 25 rows. 

 Anal plate not divided. Gastrosteges varying in number 

 from 207 to 225. Urosteges in two series of from 43 to 56. 

 The general color is black or blackish brown and yellow- 

 ish white, so arranged that most of the lateral scales are 

 black, each with a sharply defined white or yellow elongate 

 central spot. Some of the dorsal scales are similarly marked, 

 but often these are so grouped as to leave a series of solidly 

 black dorsal blotches some 41 to 85 in number on body and 

 tail. The lower surfaces are whitish, marbled with black. 

 Sometimes lateral dark blotches alternating with the dorsal 

 ones are more or less evident. The top of the head is black 

 with white markings on the rostral, internasal, and prefrontal 

 plates. Similar spots appear on the nasals, loreal, and ocu- 

 lars. The labials are light with dark edges. 



Distribution. — This subspecies is said to range from 

 Texas west into Arizona and south into Mexico (Sonora). 



Arizona specimens have been recorded as taken in Pima 

 (Tucson, Fort Lowell), Santa Cruz (Fort Buchanan), and 

 Cochise (Fort Huachuca, Babacomari Creek), counties. 



Habits. — One specimen, shot near Fort Lowell, was 

 found in a tree in the river bottom. It probably was look- 

 ing for birds' nests. 



