CROCODILIANS, LIZARDS, AND SNAKES. 649 



tlie prefreuals. In the former there is one prefrenal oa both sides, and 

 a postnasal on one side. In No. 2 there is a postnasal on each side, 

 and two prefreaals, one above tbe other, on one side only. In No. 3 

 the postnasal plate is elevate<l and is in contact above with the inter 

 frontonasal. On one side of the head it is divided by a horizontal 

 fissure into two scuta, one above the other; the other side is undivided. 

 The liinder leg measures one-third the distance from its base to the end 

 of the muzzle. When extended along the side, the fore and hinder limbs 

 just touch the extremities of each other's claws. The second and fifth 

 posterior toes are of equal length. Color pale ashen, with a bluish or 

 greenish tinge. The external edges of the scales of the second row 

 from the median line are brown, forming a longitudinal line on each 

 side. In the same way the edges of the scales of the oblique lateral 

 rows of scales are brown. These oblique brown lines are each six or 

 seven scales long ; anteriorly they become more longitudinal, two paral- 

 lel lines running backwards from above the superior border of the ear. 

 Superior labial plates brown-edged. Scales of posterior faces of limbs 

 brown edged. 



Measurements. — Length to vent, 101 mm.; length to axilla, 38 mm.; 

 length to meatus of ear, 20 mm. ; length of hind leg, 32 mm. 



No. 1 is colored like No. 3, omitting the dorsal lines; No. 2 is like No. 

 1, except that the lateral brown forms a loose band. 



This species is characteristic of the Central region of the Nearctic 

 Eealm, not occurring in the Eastern, Austroriparian, or Pacific regions. 

 It overruns a little into the borders of the Texan district and the Sono 

 ran region. It ranges from the Platte Eiver, Nebraska, on the north 

 to the city of Chihuahua on the south. Mr. Marnock obtained this 

 species near Helotes, Texas, where it is rare. I saw, but did not suc- 

 ceed in capturing, a lizard which I suppose to belong to this species, 

 near the head waters of the Medina River. It was of dark tints, with 

 light spots on the sides of the head, like the younger stages described 

 by Professor Baird. It was concealed beneath the bark of a log, and, 

 evading for a considerable time my attempts to take it, finally escaped. 



