6 OBSTETRICAL ANATOMY. 



The summit or posterior extremity likewise offers the opening of the 

 spinal canal, and a surface for articulation with the first tail-bone. The 

 central canal is a continuation of that in the other vertebrae, for the 

 passage of the spinal cord. In this bone, however, instead of being 

 circular it is triangular, and diminishes in width posteriorly. 



The position of the sacrum is more or less inclined downwards from 

 before to behind, according to the breed of the Mare. 



3. Coccyx. 



The coccygeal or tail bones are a series of small, cylindrical, or irregu- 

 larly prismatic pieces, from fifteen to eighteen in number, behind the 



Fig. -1. 



Pelvis ov the Cow. 



A, Ilium ; B, Pubis ; C, Ischium ; D, Foramen Ovale ; E, Sciatic Spine ; F, 

 Cotyloid Cavity ; G, Tuberosity of the Ischium. 



sacrum, the first three of which may be said to belong to the pelvis. 

 They form the base of the tail. 



Differences in the Bones of the Pelvis of other Animals. 



In all the domesticated animals the coxae are nearly horizontal, and 

 the ilium has a vertical direction. 



Goio. 



In the pelvis of the Cow, the space between the coxge is no greater 

 before than behind ; they are not so solid or voluminous, comparatively, 

 as in the Mare. This is more particularly the case with the ilium, the 

 iliac concavity of which is not so wide. It is more vertical than in the 

 Mare. The ischium, though thinner than in the Mare, has a much 

 wider surface, and is more curved from before to behind and from side 

 to side ; while the ischiatic spine, or supra-cotyloid crest, is very promi- 

 nent and thin. Three tuberosities are observed on the postero-external 

 angle. 



