PELVIC LIMBS 671 



for the cotyloid bone, and ossifications in the tuberosity and margin 

 of the ischial ramus, the crest, and the auricular surface. Further 

 study may reveal additional centres at the symphysis or in the 

 secondary processes of the bone. 



VAEIATIONS IN THE INNOMINATE BONE. 

 VAEIATIONS IN SIZE. 



The measurements of the innominate bone are taken as follows : 



The maximum length is the distance from the crest to the tuberosity. 



The length of the ischium is the distance from the upper border of 

 the rough space in the acetabulum to the lowest point on the tuberosity. 



The length of the ilium is the distance from the highest point of 

 the crest to the upper border of the rough space in the acetabulum. 



The length of the pubes is the distance from the middle of the 

 upper border of the rough space in the acetabulum to the upper end 

 of the symphysis. 



The length of the symphysis is the length of the straight inner 

 edge of the innominate. 



The width of the ilium is the transverse diameter at the level of 

 the auricular surface. 



The width of the ischium is the transverse diameter at the level of 

 the spine. 



The long diameter of the obturator foramen is taken parallel with 

 the symphysis. 



The short diameter of the obturator foramen is taken at right 

 angles to the long diameter and through its middle point. 



The angle which the symphysis forms with the ilium is the angle 

 formed by the meeting of the straight line of the symphysis with a 

 straight line drawn from the anterior part of the crest of the ilium to 

 the inner end of the pubes. 



The angle of the ilium with the plane of the obturator foramen 

 was taken by placing the innominate on a flat surface in such manner 

 that the ventral aspects of the tuberosity and of the anterior and 

 posterior ends of the symphysis were in contact with the surface. The 

 vertical distance from the surface to the anterior superior spine of the 

 ilium was measured, and also, on the surface, the distance from the 

 tuberosity of the ischium to the lower end of the vertical line, and the 

 angle computed from a projection on paper. 



