512 ZOOLOGY REPTILES AND BATKACHIANS OF ARIZONA. 



This species belongs to the section of the genus in which the median 

 plate behind the rostral is separated from the frontals by several small 

 plates. Originally described from Utah, its range has since been ascer- 

 tained to be general in the West, east of the Rocky Mountains, from the 

 British to the Mexican boundary. I have found it along the northern 

 boundary line, latitude 49, the northernmost point at which any species of 

 the genus is known to occur ; and in most portions of Arizona and New 

 Mexico it is one of the commonest serpents. 



50. Tropidonotus* sipedon couchi, (Ken>i.). 



Nerodia couckii, KENN., Proc. Acad. Nat. Sci. Pliila., 1869, 335 (Nuevo Leoue). 

 Tropidonotus sipedon subsp. couchii, COPE, Cbeck-List, 1875, 42. 



Resembles N. erytlirogaster [i. e., Trap, sipedon var. erythrogaster], but 

 the head is shorter and very broad, the muzzle broad and obtuse. Post- 

 orbitals three, much larger than in N. crythrog aster, the lower extending 

 forward beyond the middle of the eye. Eight upper labials, all large ; the 

 seventh much larger than in N. erythrogaster. The dorsal scales are broader 

 and less strongly keeled, and in twenty-three rows. Color uniform light 

 dull slaty brown above, paler than in erythrogaster. (Kennicott.) 



A species of the Sonoran Region as denned by Professor Cope. 



51. Tropidonotus validus, (7mm.) Cope. 



PLATE XXI. 



Regina ralida, KENN., Proc. Acad. Nat. Sci. Pliila,, I860, 334. 



TropidonotHS ralidus, COPE, Proc. Acad. Nat,. Sci. Phila., ISOfi, 310. Id., Check List, 

 1875, 42. 



Body stout for the genus. Head large, short but high ; broad poste- 

 riorly. Snout elongated, narrow, and pointed. Vertical very narrow, obtusely 

 pointed posteriorly ; occipitals small ; nineteen rows of scales, all carinated ; 

 the exterior very feebly. Light brownish-ash above, with faint black mark- 

 ings upon the bases of the scales of the first, fourth, and eighth rows; abdo- 

 men entirely uniform yellowish. (Kennicott.} 



This species, resembling the better known T. erythrogaster, was origi- 

 nally described from Duraugo, Mexico, and I only know of it as an inhab- 

 itant of the Territory from Professor Cope's indication above cited. 



* .\crodia + Regina, Bd. & Gir. 



