When one considers the poverty of the new world in bovine ruminants, it seems strange that three such anomalous forms should have fallen to its share as the prong-horn, the white goat and the musk-ox, of none of which have we the complete history; two of the number being entirely isolated species, sometimes regarded as the types of separate families.

The prong-horn is a curious compound.  It resembles sheep in the minute structure of its hair, in its hairy muzzle, and in having interdigital glands on all its feet.  Like goats, it has no sub-orbital gland nor distinct pit.  Like the chamois, it has a gland below and behind the ear, the secretion of which has a caprine odor.  It has also glands on the rump.  It is like the giraffe in total absence of the accessory hoofs, even to the metapodials which support them.  It differs from all hollow horned ungulates in having deciduous horns with a fork or anterior branch.  There is not the least similarity, however, between these horns and the bony deciduous antlers of deer, for, like those of all bovines, they are composed of agglutinated hairs, set on a bony core projecting from the frontal region of the skull.

It is well known that these horn sheaths are at times shed and reproduced, but the exact regularity with which the process takes place is by no means certain, although such direct evidence as there is goes to prove that it occurs annually in the autumn.  Prong-bucks have shed on eight occasions in the Zoological Gardens at Philadelphia, five times by the same animal, which reached the gardens in October, 1899, and has shed each year early in November, the last time on October 22, 1903,[1] and the writer has seen one fine head killed about November 5 in a wild state, on which the horn-sheaths were loose and ready to drop off.

[Footnote 1:  It is interesting to note that the first pair shed measured 7-1/4 inches, on the anterior curve; the second pair 9-1/2, and the last three 11 inches each.  The largest horns ever measured by the writer were those of a buck killed late in November, 1892, near Marathon, Texas, and were 15-3/4 inches in vertical height and 21 along the curve.]

But few of these delicate animals have lived long enough in captivity to permit study of the same individual through a course of years, and the scarcity of observations made upon them in a wild state is remarkable.  That irregularity in the process would not be without analogy, is shown by the case of the Indian sambur deer, of which there is evidence from such authority as that king of sportsmen, Sir Samuel Baker, and others, that the shedding does not always occur at the same season, nor is it always annual in the same buck; and by Pore David’s deer, which has been known to shed twice in one year.