28 Trans. Acad. Sci. of St. Lowis 
anal plates not a reliable criterion of sex in this species; 
extremities well developed. 
Coloration always dull; ventral parts white or ashy 
gray, usually with a smattering of blackish spots; dorsal 
eolor slate, brown, or blackish; vertebral stripe always 
pale or whitish, extending from occiput to base of tail; 
three pairs of dark spots along sides, these usually emar- 
ginated by pale whitish outlines; a dark spot on each 
side of neck; tail usually barred. 
Measurements taken upon 96 Kansas specimens of 
this species are summarized as follows: length of body, 
21-109 (51-60) ; length of tail, 7-44 (21-30) ; total length, 
28-148 (76-90); width of head, 6-22 (12-14); length of 
tail as percentage of total length, 21.9-34.9 (28-30) ; 
width of head as percentage of body length, 13.5-37.5 
(20-24). 
In contrast to what has been shown in other species, 
this summary indicates that there is a greater variation 
in the length of body than in the length of tail, which 
is to be expected since the tail is relatively short in 
P. cornutum. The width of the head was measured just 
back of the angle of the jaw and did not include the 
temporal spines. 
Hurter (1911) listed the total length as 110 mm., tail 
46 mm., and body 64 mm., giving a tail percentage of 
41.8, which is much larger than any noted on Kansas 
specimens by the writer. The measurements given by 
other workers for this species, so far as known, agree 
with those of the author. 
Habitat and Habits—tThere has not been a great deal 
written about the habitat and habits of this species. 
Winton (1914) and others have described the ejection 
of blood from the eye of certain specimens, but the 
writer has not been fortunate enough to observe this 
