1865.] MR. A.D, BARTLETT ON THE AMERICAN PRONGBUCK. 723 
will be found in the growth and formation of the horns of the 
Prongbuck ; it will be seen that the bony core is much smaller, when 
compared with the cavity or hollow space in the horny casing, than 
in any other hollow-horned Ruminant that I am acquainted with. 
This fact, I think, will show that the space admits of the growth and 
formation of the new horn, the bone being thickly covered with vas- 
cular integument ; and the hairs appear to grow upon the surface of 
this, beneath the old horn; the extreme point appears first to put 
on the horny matter (see fig. 4, p. 724); this increase of growth, 
acting like a wedge, forces the old horns upwards and outwards until 
they fall off. _ 
An examination of the cast horn from the living specimen at the 
Gardens, shows clearly the structure and the singular manner in which 
the hairs pass through the horny substance; that they do so is 
clearly to be seen by the casts now on the table. Being a little 
puzzled, on looking into the cavity of the cast horns, at the small 
size of the hollow, I determined to take a cast of the interior ; for 
this purpose I melted some gutta-percha and filled up the hollow 
Space, and as soon as it had become hard, I withdrew the specimen 
before you, covered, as you see, with the hairs in the same manner 
as the new horns on the head of the living animal: the roots of these 
hairs having become fixed in the gutta-percha, were drawn through 
the minute openings in the horn. This can be done easily upon any 
of the specimens of the shed horns of this animal. 
Fig. 3. 
With reference to the frequency of the shedding of the horns of 
this animal, I can only offer a surmise. Judging from the rapidity 
of the growth of the young horn, I reasonably conclude that it occurs 
annually. In support of this, it may be remembered that our ani- 
mal’s horns in January last were barely 3 inches in length, while by 
June of the same year they were fully formed, and measured 8 inches ; 
they were cast the first week in November—that is, on the 7th; the 
new horns on that day (see fig. 3) were about 4 inches long; they 
are now, this day, 6 inches long, having grown 2 inches in twenty- 
one days (see fig. 4). 
Besides this, we have the testimony of Messrs. Audubon and 
Bachman, as previously quoted, that in the month of November they 
found in the buck killed by them the soft space between the horn 
