No. 1619. HORNS OF THE AMERICAN ANTELOPE—LYON. 395 
horn, the horny tip at the apex of the core and the horny tip of the 
prong are consolidated into one solid horn. This process is repeated . 
annually, the successive horns gradually. becoming larger, until the 
maximum size is reached, which takes about five years. The fully 
mature horn has a strongly recurved and somewhat incurved tip and 
bears a well-developed prong in front. A fully developed horn is 
shown on Plate XX XVITI, fig. 5. In that specimen the tendency of 
the tip to twist backward and inward has been carried to such an 
extent that the apex has almost made a complete circle and is there 
directed forward, the horn being abnormal in this respect. There is 
no process of the bony horn-core for support of the prong in front 
nor under the extremity of the horn, both the prong and the curving 
apex being solid material. The core, however, is distinctly widened 
or marked by a very obtuse angle, corresponding to the position of 
the prong over it. The new horn, immediately after the old one has 
been cast, is very small and rests as a cap upon the tip of the blade- 
like bony horn-core. (Plate XX XVIII, fig. 3.) The remainder of 
the horn-core is covered with skin bearing long coarse hairs. ‘The 
epidermis gradually develops into horn from above downward. The 
prong begins to form before the epidermis between the tip of the horn 
and the prong has been converted into horn. (See Plate XX XVIII, 
fig. 4, where some epidermis which is being converted into horn and 
some long hairs may be seen between the prong and the tip of the 
horn above.) | 
The time of year in which the horns are shed is the autumn or early 
winter. Old bucks drop theirs earlier than do younger animals, that 
is, the oldest individuals cast their horns in the month of October, 
while younger individuals cast theirs in December or the early part of 
January. 
The mechanical factor in the dropping off of the horns appears to 
be the rapid development of a new horn on the top of the horn-core 
and beneath the old horn which is about to be shed. This newly 
growing horn pushes the old one upward, loosening it from the horn- 
core to which it has been attached by the continuity of its substance 
with that of the horny layer of the skin covering the core.“ It is also 
apparently held in position by numerous long hairs which have their 
roots in the skin covering the core, while many of their apices pene- 
trate into the substance of the horn. All observers say that when 
the horn is cast off its interior is lined with many long hairs, which 
were evidently pulled out from the skin covering the horn-core. On 
the other hand, the skin covering the core still possesses many long 
hairs whose apices once penetrated into the substance of the horn 
which has been pulled away from them. In the autumn of the year 
“Caton, The Antelope and Deer of America, 1877, p. 32, figs. 1 and 2. 
