SYNOPSES AND DESCRIPTIONS. 53 
orbit. Scales in 33—35 rows. Ventrals 229—239. Subcaudals 57 to 
65 pairs. Reaches a length of seven feet. 
With the band across the frontal and behind the eye. More or less 
spotted. Southwestern part of Mexico. (Irom descr.) 
var. BELLONA. 
Ground color lighter than in P. melanoleucus. Body more slender; 
apparently not reaching the same dimensions. In large specimens the 
bar below the eye and that across the head to the angle of the mouth 
are conspicuous. Dorsal series of spots from 70 to 80. Some specimens 
have the colors very much faded, others have the spots very black and 
distinct, particularly on the tail. The young have four alternating series 
of spots on each flank, the lower on the outer edge of the abdomen. Scales 
in 31 to 35 series. Ventrals 220—231. Subcaudals 43—63. I have taken 
this species at great distances from water on the open prairies. Rocky 
Mountain region. 
ELAPHIs. 
Exaruis Aldrovandus, 1640 and 1765; Bonaparte, 1831 and 1840; 
Duméril & Bibron, 1852 and 1854; Giinther, 1858. 
Exapue Fitzinger, 1833 and 1843. 
Of moderate slenderness, slightly compressed, belly flat; head distinet 
from the neck, crown flat, muzzle rounded; tail moderate, tapering. Eye 
medium, pupil round. Teeth equal, smooth. A loreal. Nasal in two 
parts, nostril between. Orbitals 2—2 to 3. Seales keeled, in 19 to 25 
rows. Anal bifid or entire. Subcaudals in two rows. In particular cases 
the carination of the scales becomes obsolete. 
(Scotophis.) 
Anal entire; 
Light greyish-brown (reddish in life), with dorsal blotches of brown 
or black, varying to uniform black obsoletus. 
Pale red, with darker black-bordered blotches on the back, varying to 
black, with a few white markings under the chin and neck 
guttatus. 
Anal bifid; 
with four longitudinal brownish bands quadrivittatus. 
