13. COLUBRIDJE 



been found in Texas, New Mexico, and Arizona, and ranges 

 south over the tableland of Mexico to the state of Vera 

 Cruz. In Arizona, it has been collected near Camp Apache, 

 Navajo County j Camp Grant, Graham County; Fort Lowell 

 and Sabino Canyon, Pima County; Fort Huachuca, and 

 Ramsey and Miller canyons in the Huachuca Mountains, 

 Cochise County; Otero, Sycamore, and Baboquivari canyons 

 in the Baboquivari Mountains, Pima County; and Fort 

 Mohave, Mohave County. The last locality is so far from 

 the others as to make one suspect that the specimen may have 

 been secured at some distance from the old fort. 

 This species has been recorded from "Utah." 

 The National Museum has a specimen labeled Santa 

 Magdalena, Sonora. 



Habits. — The specimen from Ramsey Canyon was found 

 just before dusk, July 29, 1912, as it was entering a hole 

 by the side of a fence post. It contained a fine large Tan- 

 tilla milcoxi which it must have just eaten. This Diadophis 

 is the largest species of the genus. 



Genus 27. Heterodon 



Heterodon Latreille, Hist. Nat. Rept., Vol. 4, 1802, p. 32 (type, 

 flatirhinos^-conCortrix); Boulenger, Cat. Snakei Brit. Mus., Vol. 

 II, 1894, p. 153; Cope, Report U. S, Nat. Mui., for 1898, 1900, 

 p. 760. 



The body is rather thick, with short tail and little if any 

 constriction at neck which is capable of lateral expansion by 

 the ribs. The snout is short, with large, prominent, recurved 

 rostral. The upper head plates are normal except that small 

 plates are often present between the rostral and frontal, 

 either between the internasals and prefrontals or substituted 

 for them. The nasal plates are distinct. Loreals are pre- 

 sent. A ring of scales surrounds the eye separating it from 



