The American Antelope 
17 
Inside of a week these knobs are again covered with a small 
cap of horn. This horn increases in size from the base, for a 
year, attaining a length of nearly six inches. The character- 
istic prong is not present at this age. In the early winter 
these horns drop off, leaving horn-cores about an inch and 
a half in length, covered, as in the first year, with a hairy 
FIG. 9. PRONGHORN. AnUlocapra americana 
City Park, Denver, Colo., Rob't B. Rockwell, Photographer 
skin. Horns immediately form on their tips, and in addition, 
at the base and in front of the horn-core another point of 
horn forms, which becomes the prong. By a gradual con- 
version of the skin covering the horn-core into 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 
2 
