HERPETOLOGY OF LOWER CALIFORNIA. 89 



compressed. The tail is conical except at its base, where 

 it is almost square in section. The limbs and head are 

 large, the latter sharply triangular and with flattened top 

 and almost vertical sides. The large nostril is in a round 

 plate, whose posterior edge is nearer to the orbit than to 

 the end of the snout. The rostral and symphysial plates 

 are very broad and low. There are ten labials. There 

 is a very large plate below the eye, and a series of large 

 superciliaries. The entire top and sides of the head are 

 covered with small irregularly hexagonal plates, which 

 are convex, except on the snout and lores. The very 

 large ear opening is almost vertical and without denticu- 

 lation. Several series of large sublabial plates pass 

 gradually into the gulars. The dorsal crest begins some 

 distance behind the shielded part of the head, is composed 

 of high spines on the nape, and gradually diminishes in 

 height posteriorly. It is continued on the middle third of 

 the vertebral line as a series of enlarged flat plates, but is 

 not traceable on the posterior third. The back and sides 

 are covered with small, smooth, subquadrate scales, which 

 pass gradually into the larger ventrals. The gular regions 

 are covered with smooth scales which become gradually 

 larger posteriorly. The smallest gulars are larger than 

 the dorsals, the largest are smaller than the ventrals. The 

 scales on the limbs are all smooth. The tail bears whorls 

 of spinose scales. The first three of these whorls are 

 separated from one another by three series of smaller 

 smooth scales; the fourth, fifth and sixth spiny whorls 

 are each preceded by two series of smooth scales, and 

 the more distal whorls by single series which gradually 

 become spinose. 



The top and sides of the head are dull pea green. The 

 back, sides, and hind limbs are pale straw color, heavily 

 washed with pale olive, and spotted and reticulated with 



