Art. VI.] ¥iY.Rmc}L-T'EKKY-}:{^KRiCK., New Mexico Lizards. 13 1 
Nevada and will doubtless be encountered in the northwestern 
parts of New Mexico, 
After careful comparison of descriptions by various authors 
we incline to believe that this but a smaller mountain-loving 
race of S. consobrinus. One of our specimens of the latter 
species is but 130 mm. but otherwise resembles the types. 
Genus. Phrynosoma. 
The horned toads are among the most characteristic of liz- 
ards and form a rather compact American group which are not 
to be confused with any other. Their bizaire spiny, disc-like 
bodies and short horned heads which they know well how to 
use in the defensive and even in offensive struggles are eminent- 
ly characteristic. The plates of the head and body are hetero- 
geneous and tend to assume the spinous form while the exist- 
ence of strong bony spines from the back of the head is a uni- 
versal character. The tympanum is distinct and may or may 
not be covered with scales. There is a transverse gular fold 
and usually a series of peripheral spines along the lateral mar- 
gins of the body. PTmoral pores are present. The tail is short 
as are the legs. The digits have keeled lamellae below. Lateral 
teeth subcoincal or indistinctly tricuspid ; no pterygoid teeth. 
No abdominal ribs. A large sternal fontanelle. Other osteo- 
logical characters may be gathered from the figures. 
In our region (eastern New Mexico) we have been able to 
distinguish but three species though there is a considerable 
range of variation which may serve to invalidate some so-called 
species. These animals are essentially insectivorous and slug- 
gish and rely upon their spinous armature for protection as well 
as upon their very considerable power of modifying the color 
of the skin to conform to the color of the station. This power 
is due to the capacity of the chromatophores to alter their form 
in obedience to nervous stimuli of varying kinds. 
They protect themselves from the extremes of heat and 
cold by burying themselves in the earth. We have never been 
able to observe that they construct burrows but they sink into 
the sand in such a way as to completely cover the body and 
