ANATOMY OF THE HORSE. 
363 
forming the substratum and basis of the entire structure. 2. A 
cuticular covering , so called from its resemblance in texture to 
the cutis. 3. A network of bloodvessels, reposing upon the for¬ 
mer, and covered by the latter. The cartilaginous structure, 
freed from its valcular connexions, is found to be wrought in the 
form of a coarse, open, irregular network, and appears designed 
mainly for the purpose of affording a bed for the lodgment and 
ramification of the bloodvessels destined to produce the wall. 
The looseness of its connexion, added to its own elasticity, ren¬ 
ders this substance peculiarly adapted to accommodate itself to the 
motions of the coffin-joint, and thus preventing those movements 
from operating prejudicially to the superimposed glandular struc¬ 
ture. 
Organization. —The coronary substance may be ranked among 
the most vascular parts of the body: no gland even possesses, 
for its magnitude, a greater abundance of bloodvessels, or of 
bloodvessels (taking them generally) of larger size; nor does 
there exist any part in which greater care appears to have been 
taken to arrange its vessels so as to insure an uninterrupted 
supply of blood. These vessels it is that produce the wall; and 
there is every reason to believe that they perform this office 
without any assistance from the vessels of the laminae. 
The Cartilages 
O 
Are two broad, scabrous, concavo-convex, cartilaginous plates, 
erected upon the sides and wings of the coffin-bone. Professor 
Coleman calls them “ the lateral cartilages,” in contradistinc- 
tion to two others he has named “ the inferior cartilages.” 
Situation. —The cartilages form the postero-lateral parts of the 
sensitive foot, extending the surface considerably in both these 
directions. 
Attachment. —The cartilages are fixed into fossae excavated in 
the supero-lateral borders of the coffin-bone. Their anterior 
parts become united, on each side, with descending lateral ex¬ 
pansions from the extensor tendon, and are also attached to the 
coronet bone by cellular membrane. Their posterior parts sur¬ 
mount the alw or wings of the bone, to which they are firmly 
fixed, and from which they project backwards, beyond the bone, 
giving form and substance to the heel. Supposing one of the car¬ 
tilages to be divided into two equal parts by a line drawn horizon¬ 
tally across its middle, the superior half, which extends as high as 
the pastern-joint, is covered by skin only; and on that account 
is quite perceptible to the feel, and even to the sight, as the 
animal stands with his side towards us. The lower half is covered. 
