APPENDIX F. REPTILES. 195 



dark brown, thus, in fact, constituting a fifth lateral series of blotches, 

 alternating with the lowest already mentioned. The throat and chin 

 are unspotted. The head is light brown, with a narrow whitish line 

 finely margined before and behind with black, which crosses in front of 

 the centre of the vertical, and through the middle of the superciliaries : 

 a second similar but more indistinct line runs parallel to this just behind 

 the rostral, and extending down in front of the eye. A third equally 

 indistinct and similar line crosses the posterior angle of the vertical, and 

 runs back on the side of the fleck, behind the labials and temporal 

 shields. There is a broad brown patch from the back part of the eye to 

 the angle of the mouth, across the penultimate and last labial. The 

 coloration is thus very different from that of H. simus, where there is 

 a distinct narrow black band across the forehead scarcely involving the 

 vertical, and passing through the eye to the angle of the mouth across 

 the last labial. Behind this a much broader yellowish band, continued 

 without interruption into the neck behind the angle of the mouth. In 

 H. nasicus the most conspicuous feature is a narrow white band, much 

 narrower than the darker patch before and behind it. The dark patch, 

 to the angle of the mouth, is much broader, continuous as it were, with 

 the broad bar between the middle and anterior light lines, which corre- 

 sponds with the narrow black line of H. simus. The other distinguish- 

 ing features are evident. The three dark patches behind the head are 

 much as in H. simus. 



In large specimens from Sonora and the Copper Mines of the Gila, 

 (Fort Webster,) the ground-color is yellowish gray, each scale minutely 

 punctate with brown. The blotches are all obsolete, only one dorsal 

 and two lateral on each side being defined by darker shades. The 

 blotches on the sides of the abdomen are wanting, but the black in the 

 middle is strongly marked. The other characters, however, are preserved, 

 except that the exterior row of dorsal scales is more or less carinated. 



Specimens of this species vary in the number of small postrostral 

 plates. In some there are only three or four, in others a larger number. 

 Sometimes, instead of a single series of median dorsal spots, there -are 

 two, in close contact, and* more or less confluent. The narrow light 

 line across the middle of the superciliaries and the high labials are 

 always highly characteristic. 



The specimen figured of natural size on Plate IV, is much smaller 

 than those alluded to from Sonora and the Copper Mines,-and upon 

 which the foregoing description has been based. 



