Vol. VIII] VAN DENBURGH AND SLEVIN— GARTER-SNAKES 263 



Thamnophis megalops (Kennicott) 

 Mexican Garter-Snake. 



Diagnosis. — Normally with eight snpralabials ; twenty-one 

 (or more) rows of scales; dorsal line distinct; lateral line in- 

 volving scales of the third and fourth rows; no light postoral 

 crescents ; preocular single ; infralabials ten. 



Type Locality. — Tucson and Santa Magdalena, Arizona. 



Synonyms. — It appears that no other names have been based 

 upon specimens of this species taken in the United States. 

 Mexican specimens have served as the types of Entcenia mac- 

 rostenima Kennicott, 1860; type locality, City of Mexico; 

 EutcBnia Havilahris Cope, 1866; type locality, tableland or 

 Southern Mountains of Mexico ; and Entccnia insigniarum 

 Cope, 1885; type locality, Chapultepec, Mexico. 



Range. — The range of this snake apparently extends over 

 most of the Mexican plateau region and north into southern 

 Arizona and New Mexico. In Arizona, authentic specimens 

 have been taken near Tucson and Fairbank. The species has 

 been recorded also from Yuma, and Fort Whipple, but these 

 records need confirmation. 



We have examined specimens of Tliamnophis megalops from 

 the following localities : — 



1. Tucson, Pima Co., Arizona. 



2. Fairbanks, Cochise Co., Ariz. 



Material. — Only six specimens from these localities are avail- 

 able. 



Variation. — The loreal is 1 — 1 in all. The preoculars are 

 1 — 1 in all. The postoculars are 3 — 4 in three, 3 — 3 in two, 

 and 4 — 4 in one. The temporals are 1+2 — 1+2 in three, 

 1+3 — 1+3 in two, and 1+2 — 1+3 in one. The supralabials 

 are 8 — 8 in four and 8 — 9 in two. The infralabials are 10 — 10 

 in all six. The scale-rows are 21 — 19 — 17 in five, 21 — 23 — 

 21 — 19 in one. The gastrosteges vary in number from 154 to 

 162; the average in five females is 158.8. The urosteges vary 

 from 72 to 77 ; the average in four females is 74.5. 



