THE PELVIS. 28 



Chauveau, in his measurements of the Horse's pelvis, gives these four 

 measurements for the inlet (mean vertical, 8^ inches ; transverse, 8A 

 inches; oblique, 8^ inches); but for the outlet only the vertical and 

 transverse (mean vertical, Oi inches ; transverse, 7 inches). Eainard, 

 for the inlet, j^ives three diameters ; (1) a supcro-inferior, from the sacro- 

 lumbar articulation to the anterior border of the ischio-pubic sympliysis; 

 (2) a tranavcrse, from the inner surface of the cotyloid angle on one side 

 to the same point on the opposite side ; (3) a vertical, from the middle 

 of the sacrum to the ischio-pubic symphysis in the larger animals, and 

 to the sacro-coccygeal articulation in the smaller. But for the outlet he 

 lias only two diameters: (1) a vertical, from the posterior part of the 

 ischio-pubic symphysis perpendicularly to the sacrum or its prolonga- 

 tion, the coccyx ; (2) a transverse, from one ischial tuberosity to the 

 other. 



The most important diameter is certainly that between the middle of 

 the sacrum and the ischio-pubic symphysis in the larger animals, and 

 the sacro-coccygeal articulation and ischio-pubic symphysis in the 

 smaller creatures. For it must be remembered that the pelvis of the 

 domesticated animals oilers a very inclined plane, and if, placing it in 

 the position of the human pelvis, we draw a horizontal line from the 

 symphysis towards tlie spine, it will be found that this line does not 

 touch the sacro-lumbar articulation, but the middle of the sacrum in the 

 large, and the sacro-coccygeal articulation in the smaller animals. This 

 point is the nanrowest through which the fatus has to pass, and in 

 which it will meet most resistance ; for while the top of its shoulder is 

 towards the sacrum, its chest is resting on the pubis. So that it may 

 be said that this is really the first solid resistance to be overcome in 

 parturition. 



Considering the variations in size in some species, it is not possible to 

 give general measurements for all ; but we may follow the example of 

 Eainard, and give average diameters for different-sized animals. These 

 are tabulated as follows; the last column, headed ' Symphysis,' gives 

 the length of the floor of the pelvis. 



