Io VETERINARY OBSTETRICS. 
into two faces, three borders, and three angles. The 
superior face is smooth and concave; the inferior has 
a large groove for the pubio-femoral ligament. The 
anterior border is thin and rough, the posterior thick 
and concave, and assists in forming the obturator 
foramen; the internal border is thick and articular. 
The external or cotyloid angle forms the bottom of the 
cotyloid cavity; the internal and posterior angles are 
articular. 
The sacrum results from the fusion of five verte- 
bre into a single, voluminous, pyramidal or triangular 
mass. It may be said to terminate the vertebral spine 
posteriorly. It encloses the pelvic cavity above, and 
articulates in front with the last lumbar vertebra, 
behind with the first coccygeal, and laterally with the. 
ossa tnnominata. It is divided into two faces, two. 
borders, a base, an apex, and a central canal. The 
superior face presents the spinous processes forming 
the sacral spine, bent backwards and diminishing in 
length posteriorly; it offers on each side the four 
supra-sacral foramina. The inferior face is smooth 
and shows the lines of separation of the vertebre, and 
on each side the four sub-sacral foramina. The borders. 
are thick and concave, rough posteriorly, having forward 
a broad, rough auricular surface to articulate with the 
ossa tnnominata.. The base offers, on the median line, 
the anterior orifice of the sacral canal, and the anterior 
articular head of the body of the first sacral vertebra ; 
on the sides, the articular processes and the anterior 
notches of that vertebra, and the outside, the two large 
facets for articulation with the last lumbar vertebra. 
