1911] Bryant: Horned Lizards of California and Nevada 61 
SUMMARY 
1. The bases for generic and specific distinction among the 
horned lizards have not as yet been generally accepted owing to 
the diffieulty experienced in finding dependable characters. This 
study of the horned lizards of California and Nevada shows that 
there are diagnostic osteological characters which in addition 
to the characters now separating the species might, by the work- 
ing out of a key from a complete set of specimens of all the 
species, furnish the necessary characters for a revision of the 
genus. 
2. A study of the osteology of the different species inhabiting 
California and Nevada was productive of at least four inter- 
esting features. (a) The closure of the supratemporal openings 
by the meeting of the postorbital, supratemporal, and parietal 
elements in Anota maccalli, a character heretofore unknown 
among the Lacertilia. (b) The attachment of the third sternal 
ribs to the xiphoid rods, a peculiarity of Phrynosoma platyrhinos. 
(c) A supporting of epidermal sublabial spines by bony processes 
from the lower mandibles in Phrynosoma platyrhinos and Anota 
maccalli. (d) The presence in all of the species of a well-devel- 
oped postischial symphysial cartilage which, in some species, 
showed a tendeney to ossify. 
3. A contribution to the slight knowledge of the ‘‘ejection of 
blood’? by horned lizards was afforded by certain experiments 
carried on by the writer. A few notes on the hibernation of a 
horned lizard adds something to the limited knowledge of this 
habit. 
4. Five species and subspecies of horned lizards inhabit the 
states of California and Nevada, each species and subspecies 
occupying an area fairly well defined. An overlapping of these 
areas of distribution takes place in at least three localities. 
5. The species known as Phrynosoma blainvillec and Phry- 
nosoma frontale are separated by very subordinate characters 
(characters much less diagnostic than those separating other 
species of horned lizards) and show an intergradation at the 
line of contact of their areas of distribution. They are there- 
fore but geographical races and are reduced to subspecific rank 
