74 SYNOPSES AND DESCRIPTIONS. 
vertically compressed, so as to appear pointed in a side view, ¢rowding 
backward between the oblique internasals. Nasal in two parts, nostril 
between. A loreal. Oculars 1—2. Temporals 2+3. Labials eight, 
fourth and _ fifth in orbit, seventh largest. Infralabials nine, fifth largest. 
Submentals one pair, followed by four small shields. Scales lozenge-shaped, 
smooth, flat, in 23 rows, outer broader. Ventrals broad, 191—206. Anal 
entire. Subcaudals 40—49 (on one specimen half of them are divided). 
Black, red and yellow in life. In alcoholi¢ specimens uniform yellowish 
white, with about thirty-three transverse black bands, separated by nar- 
rower spaces—26 to the vent. Each black band is composed of a narrow, 
about three 
elongate, subquadrangular spot on the middle of the back 
scales long by five in width—and a wedge-shaped extension of black scales, 
with yellow spots, down each flank to the edge of the abdomen. On the 
outer two rows and the extremity of the ventrals on each side there is a 
series of irregular black spots, twice as many as there are of the bands. 
The spaces between the black bands were red. Each scale has a black 
spot in the center. Head black from frontal to neck. On each side of 
this the scales are black, with light centers. Upper labials margined 
with black. Muzzle yellowish. 
The pattern of coloration is about as below. A dorsal series of elon- 
gate black spots—about 26 to the vent—separated by spaces equal or 
smaller, a series of twice as many small black spots on the flank—placed 
opposite the extremities of the former—and a third series on the edge of 
flank and abdomen alternating with the series above it. The increase of 
the amount of black on the scales tends to form bands and obliterate the 
original pattern. Southern California to Mexico. 
var. TESSELLATUS. 
Labials eight. Infralabials ten. Ventrals 178. Subcaudals 37 entire, 
plus 14 pairs. Coahuila, Mexico. 
HETERODON. 
Beauvois, 1799; Latreille, 1800, Hist. Rep., IV, 32. 
Of moderate size. Body stout, belly flat. Head short, broad, little 
larger than the neck. Snout very prominent, shovel-shaped. Rostral a 
produced trihedral. Posterior maxillary teeth larger, separated from the 
