SKELETON OF THE WILD DUCK. PELVIC GIRDLE. 325 



The ilium (figs. 58 and 61, 1) is the largest bone of the 

 pelvis. It forms a long flattened plate extending for a con- 

 siderable distance both in front of and behind the acetabulum, 

 and is fused along its whole length with the transverse pro- 

 cesses and neural spines of the sacral and pseudosacral verte- 

 brae. It forms more than half the acetabulum, above and 



FIG. 61. LATERAL VIEW OF THE PELVIS AND SACRUM OF A DUCK (Anas 



boschas) x 



1. ilium. 



2. ischium. 



3. pubis. 



4. pectineal process. 



5. acetabulum. 



6. ilio-sciatic foramen. 



7. fused vertebrae. 



8. antitrochanter. 



behind which it is produced to form a process, the antitro- 

 chanter (fig 61, 8), with which the great trochanter of the 

 femur articulates. 



The ischium (figs. 58 and 61, 2) is a flattened bone which 

 forms about one-third of the acetabulum, and lies ventral to the 

 posterior part of the ilium. Its anterior portion is separated 

 from the ilium by the large oval ilio-sciatic foramen (fig. 

 61, 6), while behind this the two bones are completely fused. 



The pubis (figs. 58 and 61, 3) is a very long slender bar 

 of bone which forms only a very small part of the acetabulum 

 and runs back parallel to the ventral surface of the ischium 

 with which it is loosely connected at its posterior end. For 

 the greater part of their length the two bones are separated by 



