SKINNER — THE PRONG-HORN 
87 
the nipple, is a thick velvety membrane, a special development and 
continuation of the outer skin, carrying long, bristle-like hairs with 
more of these hairs extending up the horn from the base of the core. 
This membrane and the bristly hairs gradually agglutinate into the 
nipple. The agglutinated material becomes true horn, the change 
slowly proceeding towards the base until the whole core is sheathed 
with horn in which the remaining unchanged bristly hairs are imbedded, 
even to the very tip of the prong and well up towards the main tip. 
At the time the old horn is shed in November, the new horn extends 
down from the tip from half an inch to two inches according as the 
sheath was prematurely shed or not. The horny sheath forms, and 
extends downward about two inches per month until January first, and 
then about fifty per cent faster until the first of March, when the horn, 
in normal adult bucks, is almost a foot in height, is curved back and 
inward, sometimes so as to be truly lyrate. The horns of both sexes 
are normally black, but the bucks manage to use theirs enough to 
keep the tip worn down so as to expose a bit of whitish horn material 
beneath. The prong (one is normal but occasionally an extra one 
appears or two appear beside the larger one) on the growing sheath 
starts to grow about January first, appearing as a small button just 
discernible through the hair still extending up more than half the 
length of the coming horn. The prong grows with the sheath to com- 
pletion at the same time ; as it grows it loses its bluntness and becomes 
compressed and sharp. The horns of the kids, very small and not 
easily seen the first summer, start active growth in February when the 
kid is about ten months old and gradually swell up two inches during 
the next two months, and may grow from the base for ten months 
longer to a total height of four inches. Afterwards the horn is shed and 
renewed as already described. The prong appears sometimes before 
the youngster is two years old, but is then hardly more than an indica- 
tion of what it becomes later. Horns continue to grow larger each 
year until the animaPs full growth is attained at the age of five. The 
fully developed horn is recurved and normally the tip inclines inward, 
but on a few rare occasions I have seen the tip turned forward instead 
of back. This variability in direction of the recurved tip is probably 
due to the fact that the horn core does not extend into the bend of the 
sheath and therefore cannot direct its growth. Neither does the 
prong have the benefit of any support from the core, and its tip usually 
turns in more or less. The core, however, is widened, or at least marked 
by an abrupt angle, under the prong. 
