654 13. COLUBRIDZ 
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; 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 wilcoxi which it must have just eaten. This Diadophis 
is the largest species of the genus. 
Genus 27. Heterodon 
Heterodon LatTrEILLe, Hist. Nat. Rept., Vol. 4, 1802, p. 32 (type, 
platirhinos==contortrix); BouLENGER, Cat. Snakes Brit. Mus., Vol. 
II, 1894, p. 153; Cops, Report U. S. Nat. Mus., 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 
