118 . OPHIDIA. 
Body elongate, compressed ; tail slender; head moderate, rounded in front, distinct 
from neck; eye large; mouth deeply cleft. Rostral shield much broader than high, 
very obtuse above, just reaching the surface of the head ; anterior frontals short, much 
broader behind than in front; posterior ones much larger; vertical five-sided, very 
broad in front, with an obtuse angle behind, and convergent, very concave lateral 
edges; superciliaries very broad posteriorly; occipitals short, small, obtuse behind. 
Anterior ocular large, raised to the surface of the head, but not reaching the vertical ; 
two posterior oculars; one loreal; two large nasals, nostril between; eight or nine 
upper labials; scales in twenty-one or twenty-three rows, those of the dorsal rows 
keeled; keels of the three medial rows excessively strong. Scales rather elongate, much 
imbricate, especially on the neck; ventral plates raised on the sides, 202-208; anal 
entire ; subcaudals 126-132. Above uniform brown, except some scales of the 
medial row, which are yellow with black tip ; head yellow and brown variegated ; belly 
anteriorly uniform yellowish, ventral plates black-edged about the middle of body, 
posteriorly entirely black. 
Length of cleft of mouth 13 inch, length of tail 18 inches; total length 5 feet 3 inches. 
The number of upper labials, as well as their disposition, varies. One specimen has 
nine on both sides, the fourth, fifth, and sixth entering the orbit ; a second shows the 
same arrangement on one side, but has eight labials only on the other, the fourth and — 
fifth entering the orbit; the third specimen has eight labials on both sides, but on one 
the third, fourth, and fifth enter the orbit, on the other the fourth and fifth only. 
If I am right in referring 7. lunulatus, Cope, to this species, the young would have a 
more variegated coloration with darker cross-bands, which is, in fact, most likely the case. 
4. Spilotes argus. (Tab. XLIV.) 
Spilotes argus, Bocourt, Miss. Sc. Mex., Rept. p. 692, t. 48. figg. 10, 10 a-f. 
Hab. Mexico (Mus. Brussels), Atoyac in Vera Cruz (H. H. Smith). 
Body and tail moderately elongate; head rounded in front ; eye large, three-fifths of 
the length of the snout. Rostral shield rather broader than high, obtusely rounded 
above, just reaching the upper surface of the head. Anterior frontals half the size of 
posterior; vertical broad, with the lateral margin slightly concave, as long as the 
occipitals, which are obtusely rounded behind. Loreal longer than high; the single 
preocular large, raised to the surface of the head, but not reaching the vertical ; two 
postoculars; ten upper labials, the fifth, sixth, and seventh, or the sixth and seventh 
only, entering the orbit. Temporals rather irregular, 2+2, but one only is in contact 
with the postoculars. Scales much imbricate, those of the median rows faintly keeled, 
in twenty-three series. Ventrals 213; anal entire; subcaudals 88+. The teeth of 
this species increase so slightly in size behind, that the dentition may well be described 
as isodont, ‘The upper and lateral parts are black, each scale being provided with a 
yellow spot; on the scales near the head the yellow spot is small, but farther behind 
