THE PELVIS. 



19 



transverse diameter of the inlet. It therefore results that the pelvis of the 

 Cow is more cylindrical and less conical than that of the Mare ; but this fea- 

 ture does not render parturition any easier, for though the outlet is a little 

 larger than in the latter animal, yet this advantage is counterbalanced by 

 the length of the pelvic cavity, the greater extent of its bony walls, and 

 the very marked curvature of the symphysis. So it is that, while it rarely 

 happens that the foal experiences any difficulty in passing through the 

 pelvis, once it has fairly cleared the inlet, it is not at all infrequent for 

 the calf to become fixed in the pelvis, and to remain there unless removed 

 by artifical means. 



It is also to be noted that the floor of the pelvic cavity is on a much 



Fig. 7. 

 Longitudinal Section of the Cow's Pelvis. 



higher level than thaj of the abdomen ; so that a kind of steep step has 

 to be ascended by the calf before it can enter this passage ; consequently, 

 it often remains fixed against this upper level at the inlet. 



Sheep and Goat. 



With these animals the pelvis does not differ to any notable extent — 

 except, of course, in size — from that of the Cow. The symphysis is nearly 

 rectilinear in its direction, and its ossification occurs at a very much later 

 period than in the Cow or Mare ; this allows the diameters of the pelvic 

 cavity to be increased during parturition, and accounts for the rarity of 

 difficult births in the Sheep and Goat. 



Pig. 



The general conformation of the pelvis in the Pig is not unlike that of 

 ruminants, except that the sacro-vertebral angle, or "promontory of the 

 sacrum," is more salient, the canal longer, the plane of its anterior cir- 

 cumference more oblique, and the direction of the ischio-pubic symphysis 

 perfectly rectilinear. The /<?/z;zV ^r.a'z///); is very large in proportion to the 

 size of the young at birth ; therefore it is that accidents are very rare 

 during the act of parturition. 



Bitch and Cat. 



In these creatures the sacro-vertebral angle is still more marked, and 

 diminishes the inlet of the pelvis to a notable extent ; the direction of 

 the symphysis is rectilinear, and the general outline of the pelvic cavity 



