1886.] SO-CALLED PELVISTERNUM. 16S 



millim. 



Length of ilium 140 



Crest 20 



Breadth opposite the acetabulum 35 



Length of pubis 55 



Interpubic bone, antero-posterior diameter .... 15 



„ ,, breadth of one side 35 



In Phacochcerus the bone occupies the position of the triangular 

 ligament in man, and is three-cornered and wedge-hke. The following 

 measurements were made : — 



millim. 



Length of os innominatum 250 



Crest .. 120 



Breadth of ilium above acetabulum 32 



„ „ at acetabulum 70 



,, „ below acetabulum 34 



Arch of pubis 75 



Interpubic bone, breadth 24 



„ „ superior depth .. 15 



„ „ inferior depth 30 



„ ,, thickness at base 20 



In the skeleton of the Beaver the bone is not so distinct as in 

 Phacochcerus. The following are the measurements : — 



millim. 



Length of os innominatum 160 



Crest 30 



Breadth opposite acetabulum 35 



Arch of pubis 75 



Depth of pubic bone 9 



Breadth of one half 25 



I do not find the bone present in any other mammalian skeletons 

 that I have examined. The bone occupies the position of the 

 triangular ligament and the os cloacse of Lacertilians. Ligaments and 

 fasciae are so often the seat of ossifications, and bones in one set of 

 animals are so often represented by hgaments in another set, that 

 one is almost tempted to regard the bones above referred to as, in 

 whole or in part, homologous with the triangular hgament of the 

 urethra found in the higher animals. 



The interpubic bone in Bradypus is mentioned by Prof. Flower in 

 his 'Osteology.' 



