100 
JOUKNAL OF MAMMALOGY 
On another day on the main road, I had a small male antelope come 
up to within a hundred feet to watch me ride past. As I did so, he 
squealed and stamped first one fore foot and then the other, and then 
trotted up and crossed the road in front of my horse. On another 
occasion I approached a group of twelve animals standing on a knoll. 
Most of them moved off, leaving one that permitted me to pass within 
fifty feet. After I had passed he started suddenly to run and was 
almost instantly at full speed and seemed to grow more and more 
frightened the farther he ran. 
Such occurrences are common enough almost daily; and when we are 
in camp on the prong-horn range, we so often have a single animal, or 
even a group of three or four, come up to inspect camp and stay about 
for some time, that it arouses little comment. Where blinds are built 
for photographic purposes, they usually result in attracting, sooner or 
later, most of the antelopes in the vicinity. My experience has been 
that single animals are more apt to show this inordinate curiosity, 
still I have had considerable bands come close to my blind at times. 
Naturally the broad open plains on vrhich the prong-horns live, and 
the fact that they depend more on eyesight and their sense of smell, 
make calls and sounds more or less superfluous and create the necessity 
for other signals. They have an alarm note that might be described 
as either a squeal or a bark, and they use it when curious as well as 
when alarmed. But one of the great characteristics of this animal is 
its ^‘signallings’ with its rump patch, whose dazzling white hairs can be 
erected or depressed at will. In times of excitement, alarm, and pain, 
these patches are erected, forming two “great chrysanthemum-like 
white rosettes,” as Dr. E. W. Nelson expresses it, that instantly attract 
attention and can be seen for a long distance. The prong-horn, first 
giving the signal, turns so that all his companions can see it, sometimes 
it is constant and sometimes the alternate raising and lowering gives a 
quick series of flashes. A second animal seeing the signal, repeats and 
the alarm is flashed from point to point across the plains as if from a 
series of heliograph stations. Then all the animals run together into a 
small, compact band, if it is at all possible. As they dash away, the 
white signals can be seen for a long distance; as the animals halt and 
face about, the signals disappear and the otherwise neutral color causes 
the animals to fade out as by magic. But if there is still cause for 
alarm, the white signals flash out again and again long after the rest 
of the animal has become invisible. Upon investigation it is found that 
there is a mass of muscle underlying the buttock patches and glands 
