204 COPE. (Vou. IID.. 
motherium, a median osseous horn, since postero-lateral angles 
of the skull are wanting. In the Dinocerata and the Artiodac- 
tyla, where the temporal crests are lateral, leaving a wide fronto- 
parietal plane with posterior lateral angles, horns are devel- 
oped. In members of both groups horns have been developed 
over the orbits also (Fig. 43), and in the Dinocerata on the ex- 
tremities of the nasal bones as well. These growths are all on 
parts which are subject to especial irritation by contact with 
other bodies, animate and inanimate. 
Among Artiodactyla, the deer (Cervide) are especially dis- 
tinguished by the periodical shedding of all but the bases of 
their horns. Extinct forms found in the Upper Miocene of the 
United States and France (the Loup Fork series) furnish the 
explanation of the origin of this remarkable peculiarity. In the 
genus Cosoryx we find that the horns may or may not possess 
a burr near the base of the beam, like that of the deer; the 
same species being indifferently with it or without it. This 
observation has been made on three species, —the C. necatus, 
C. furcatus, and C. ramosus. The following explanation of these 
facts has been proposed by myself.! “From the facts of the 
case the followmg inference may be derived, premising that it 
is very probable that a genus allied to the present one has given 
origin to the family of the deer. It is obvious that the horns 
of (Dicrocerus) Cosoryx did not possess a horny sheath as in 
the Bovide, from the fact of their being branched. As the 
sheath grows by addition at the base, the presence of branches 
which necessarily obstruct its forward movement, would be 
fatal to the process. There is much to be said in favor of the 
view that the horns were covered with an integument, probably 
furred, as in the giraffe and young stage in the deer. Thus 
there are grooves in the surface of the beam for superficial 
blood-vessels, which must have been protected by skin (I do 
not observe these grooves on the beam of C. ¢eres). The reten- 
tion of the broken extremity of an antler, so as to be reunited, 
as described (Fig. 43, 3), could not have been accomplished 
without an integument. The presence of the burrs cannot be 
accounted for on any other supposition, as there are no foramina 
to give exit to nutrient vessels at the point where they exist ; 
LU. S. G. G. Survey west of the 100th Mer., G. M. Wheeler: iv., Paleontology, 
1877, p. 348. 
