160 BULLETIN Gl; UNITED STATES NATIONAL MUSEUM. 



black pigment does not always encroach upon the keels, which fre- 

 quently retain their characteristic rufous tint; but when well devel- 

 oped they often encroach upon the dorsal and lateral stripes, giving 

 them a wavy or interrupted appearance. In a number of specimens 

 which have been examined (mostly from the northern part of the 

 range, see below) the spots in the second and third rows fuse on the 

 anterior part of the body to form distinct cross-bands between the 

 stripes, occasionally also uniting with those of the first row, thus 

 intersecting the lateral stripe. This tendency has not been noted to 

 take place for more than seven spots posterior to the nuchals, which 

 in these specimens are usually fused across the nape and strongly 

 notched posteriorly by the dorsal stripe. 



Belly grayish white, light yellow or light greenish yellow. The 

 usual narrow, black bar, and ventral spots may occur alone or together, 

 but in any case rarely show much beyond the edges of the superincum- 

 bent scute. The ventral plates are rarely speckled with darker. The 

 head above is usually dark brownish olive splashed with black. The 

 supralabials (with the exception of the last), lower and middle post- 

 oculars, and the lower part of the preoculars are usually pale yellow; 

 supralabials well margined with black. The last labial is usually 

 more dusky, approaching the body color. Generally many of the 

 infralabials are also margined with black. 



Habits and habitat relations. — Apparently the only observations 

 that have been recorded upon the habitat preference of this snake are 

 those on the three specimens taken in Sabino canyon, Santa Catalina 

 Mountains, Arizona, in 1907 (Ruthven, 1907, 588). "All of the speci- 

 mens obtained were found near the stream in the canyon. Two were 

 lying on rocks in midstream, the other on the immediate shore. When 

 frightened they immediately took to the water, swimming in the 

 swift current with apparent ease. They doubtless subsist largely 

 upon the frogs and tadpoles which abound in this habitat." Bailey 

 records it in the Davis Mountains, Texas, at an altitude of 5,700 feet. 



Range. — T. eques is known to range over more degrees of latitude 

 than any other garter-snake that inhabits Mexico, except proximus. 

 The range extends from central Guatemala on the south to the high 

 plateau in central Arizona and New Mexico on the north. Specimens 

 have been examined from the following localities: "Central Guate- 

 mala," Escuitla, Guatemala; valley of Mexico and Toluca, Mexico; 

 Veracruz, Zacaultipan, Hidalgo; Guanajuato; Rinconado, Puebla; 

 Durango and Coyotes, Durango; Fort Apache, Fort Huachuca, 

 White River Canyon, Sabino Canyon (Santa Catalina Mountains), 

 Fort Wliipple, Arizona; San Ildefonso, Lake Valley, New Mexico; 

 Davis Mountains, Pecos, Helotes, San Antonio, Texas. 



The literature on this form is rather extensive, but, as far as I can 

 find, no specimens have been recorded outside of the region outlined 



