134 OPHIDIA. 



pair subquadrate. A small loral. Three or four postorbitals ; 

 two anteorbitals or one only. Temporal shields small, scale-like. 

 Dorsal rows of scales twenty-nine to thirty-five, variable in some 

 species; those on the back carinated, on the sides smooth. Abdo- 

 minal scutellae, two hundred and nine to two hundred and forty- 

 three ; preanal one large and entire. Subcaudal scutellae all 

 divided. Ground color whitish or reddish-yellow, with a triple 

 series of dorsal black blotches, largest in the middle series. 

 Several series of smaller blotches on the sides. Abdomen unicolor 

 or maculated,- with an outer row of blotches. Head of the same 

 color as the body, maculated with black ; a narrow band of black 

 across the upper surface between the eyes, and a posterior vitta 

 on each side, extending obliquely from the eye to the angle of 

 the mouth. A black, vertically elongated, patch is often seen 

 beneath the eye. 



S?y.Pituophis, HOLBR. N. Amer. Herp. IV, 1842, 7. B. & G. Catal. N. Amer. 

 Rept. I, 1853, 64. BUM. & BIBR. Erpet. ge"n. VII, I, 1854, 232. 



Pityophis (Holbr.), HALLOW. Proc. Acad. Nat. Sci. Philad. VI, 1852, 181. 



Churchillia, B. & G. Rept. in Stansbury, Expl. Vail, of Gr. Salt Lake of Utah, 1852, 

 350. 



OBSERV. The species of this genus generally attain a very large 

 size. They are known in the United States, to which they chiefly 

 belong, under the common appellations of pine, bull, and pilot snakes. 

 They are of terrestrial habits. Quite timid in spite of their great 

 size, they will hiss at the approach of the slightest danger or alarm, 

 by suddenly inflating their lungs and letting the air escape again. 

 Their body and head both, will, in such cases, be somewhat flattened, 

 though never to the same extent as in Hcterodon, or "blowing viper," 

 as the latter are commonly called. Under ordinary circumstances, 

 the vertical diameter of their body is greater than the transversal, 

 the reverse of what we observe in the subaquatic garter-snakes (Eutae- 

 nid). The head, in some instances, is quite narrow and tapering ante- 

 riorly. Oftentimes there are three pairs of frontal plates, one more 

 than is usually the case : a prefrontal pair and two postfrontal pairs, 

 the latter placed side by side. 



The teeth are equally developed and rather inconspicuous. There 

 are none upon the premaxillary bones. 



