32 EQUINE ANATOMY. 



is rough, the external thick and concave, the internal thin and 

 concave, forming the great sciatic notch. 



The extei-nal angle, or anterior superior spinous process is thick, 

 wide and flat, and called the angle of the haunch. The internal, 

 ox posterior superior spine, curving backward and upward, is called 

 the angle of the croup. The posterior angle forms part of the 

 cotyloid cavity ; above this cavity is the supi-a-cotyloid crest, two 

 rough points for origin of the rectus, and ilio-pectineal eminence 

 at the junction with the pubes. 



THE PUBIS. 



The pubis is flattened from above down, elongated transversely, 

 and has tivo surfaces, three borders and three angles. It lies in- 

 side the ilium and in front of the ischium. 



The superior or pelvic siciface forms the pelvic floor, and is 

 smooth and concave. 



The inferior surface is rough and convex and shows a groove 

 for the pubio-femoral ligament. 



The anterior boi'der is rough, the internal is united with the 

 opposite to form the symphysis, and the posterior forms the an- 

 terior boundary of the obturator foramen. 



The external or cotyloid angle forms the bottom of the cotyloid 

 cavity. 



The internal unites with the opposite. 



The posterior is united with the ischium. 



THE ISCHIUM. 



The ischium hes behind the pubes and ilium, and is the smallest 

 of the three portions. 



It has two surfaces, a superior or pelvic, smooth, and an in- 

 ferior, rough, fot/r borders and four angles. 



The anterior border bounds the obturator foramen, the posterior 

 diverging forms the sciatic arch, and shows the ischiatic spine. 



The external is concave, forming the lesser sciatic notch. 



The internal unites with the opposite to form the ischial 

 symphysis. 



The antero-external angle forms part of the cotyloid cavity ; the 

 antero-internal unites v\'ith the pubis ; the postero-external forms 

 an enlargement, the tuberosity ; the postero-internal unites with 

 the opposite. 



The cotyloid cavity (or acetabulum) is a deep excavation, at the 



