84 
JOTJKNAL OF MAMMALOGY 
brownish black in the male. There are white areas around the horns 
and at the base of the ears. The blackish markings are much more 
noticeable on the old males than on the does and younger animals. 
In typical americana the black sometimes occupies the whole face 
below a line connecting the horns, but usually this area is T-shaped 
with the horizontal line between the horns and the vertical line down 
the nose. In mexicana and peninsularis, the blackish area becomes 
dark brown, and is more restricted. In all forms, the eyelashes are jet 
black. There is a black edge to the ear, and a black line, in the male, 
outlines the edge of the lower jaw, starting just below the ear and 
extending down for several inches, less on younger bucks than on 
older animals. This latter is a sex mark, distinguishing the male at 
all ages, and even appearing on some fetal specimens. The tail is 
white, or nearly so. The small pointed hoofs are double and black; 
the two small rudimentary hoofs, usually seen on ruminant animals 
on the rear legs above the genuine hoofs, are absent.^ 
The amounts of black, brown, and white differ in this animal according 
to season, sex, and age. 
Young prong-horns, until a month or two old, are paler than their 
parents, and the rump patch is tinged with pale russet and is not 
distinct — but it is interesting to observe that the rump can be erected 
by a kid but a few hours old — indeed all of the pattern is obscure, the 
white areas are stained with dull buff, and the blackish parts are only 
faintly indicated. Little curls of dusky hair mark the location of the 
coming horns of the male. 
A full-grown prong-horn is about four and a half feet long and 
between three and four feet high at the withers. A few weights are 
recorded by Mearns: an adult male weighed 112 pounds as killed, after 
bleeding; an adult female weighed 109 pounds as killed, after bleeding; 
three adult males weighed 64, 56, and 67 pounds, respectively, after 
removal of head, feet, skin, and viscera. 
The ear stands erect when the prong-horn is at ease, giving the animal 
an alert and striking appearance. When he becomes excited, the ears, 
which are wonderfully acute, are projected forward to catch the slightest 
sound. They are five inches high, three inches broad at the widest 
place, terminate in a point, and are covered inside and out with hair. 
The eyes are black, lustrous, very expressive, and so large that taxi- 
dermists find them to exceed those of the horse and ox in size, and to be 
very nearly equal to those of the elephant. 
2 Adapted from Mearns, Bull. XT. S. Nat. Miis., No. 56, pp. 221-222, 1907. 
