206 COPE. [Vot. III. 
bat, or accidental contact with hard substances. The integu- 
ment would be stripped up to near the junction of the antlers 
with each other, or of the beam with the cranium, and the 
arteries would be constricted or closed at those points. It is 
near these junctions that all of the burrs are found. But as 
such lesion would be necessarily less complete at the point 
where the horn has greatest circumference, so the entire death 
of the horn might be less usual than that of the branches. 
Should such lesions have occurred for a long period at the 
breeding season, nature’s efforts to repair by redeposit of bony 
tissue might as readily become periodical as the increase in 
size and activity of the reproductive organs and other growths 
which characterize the breeding season in many animals. The 
subsequent death of the horn would be at some time followed 
by its shedding by the ordinary process of sloughing.” 
Cosoryx is not the true ancestor of the Cervida, as its teeth 
have already attained the prismatic type of the higher Bovide. 
But Blastomeryx is most probably the ancestor of the deer. 
The remains of this genus occur with those of Cosoryx, but the 
burr has not yet been observed on its horns. 
2. THE VERTEBRAL CENTRA. 
a. The Articular Faces. 
The mutual articulations of the vertebral column are these of 
the centra and of the zygapophyses. Many important modifi- 
cations in these articulations are to be seen in Vertebrata, 
the Reptilia presenting the greatest variety, excepting in the 
zygapophyses, which are tolerably uniform in that class. In 
the Mammalia modifications of the central articulations are not 
more striking than are those of the zygapophyses. 
The forms of central articulation are four ; viz.: the amphicce- 
lous, the ball-and-socket, the plane, and the saddle-shaped. The 
first type is only seen in a very imperfect degree in Mam- 
malia and in but very few vertebrze, where it is indeed but a 
modification of the plane. The ball-and-socket is chiefly found 
in the neck of long-necked Mammalia, as the higher Diplar- 
thra, and to a less degree in their lumbar regions, while the 
dorsal vertebrze present an approach to the same type in the 
same groups. The saddle-shaped centrum is only found in 
