ANATOMY. 15: 



sacrum and first two or three coccygeal vertebrae; 

 inferiorly, to the superior ischiatic spine and tuberosity 

 of the ischium. 



The Mare's pelvis represents a somewhat cone- 

 shaped cavity at the posterior part of the trunk, 

 continuing the abdominal cavity. It has an internal, 

 and an external surface, and two openings. 



The anterior opening is termed the inlet of the^ 

 pelvis, by which the foetus enters the pelvic cavity. 

 The posterior is known as the outlet or recto-urethral; 

 opening. 



Fig. 6. 



Diagram of the Mare's Pelvic Axis. 



A, Inlet ; B, Outlet. 



The diameters of the inlet are generally recognized; 

 as two : The supero-inferior or sacro-pubic, which is 

 the width between the sacro-vertebral angle and the 

 symphysis pubis. It varies with the size of the animal, 

 'but is usually between eight and ten inches. The 

 transverse or bis-iliac diameter is the distance between 

 one ilio-pectineal crest and the other. From seven to^ 

 nine inches. 



