XVII.] 



MARSUPIALIA. 



r-s 



In. the Kangaroo (Macropus, Fig. 116), the three surfaces 

 of the ilium are also well marked and nearly equal : but the 

 whole bone is curved outwards at the upper end. 



In the Thylacine and Dasyures the ilia are compressed 



laterally, the acetabular and pubic 



borders meeting above in front, so that 



the iliac surface is (as in the Carnivora) 



very narrow, and disappears in the 



upper half of the bone, the "crest' 



being formed by the united edges of 



the sacral and gluteal surfaces ; where- 

 as in the wide, depressed pelvis of the 



Wombat (Phascolomys\ the flattening 



has taken place in the contrary direc- 

 tion, and the iliac surface spreads out 



to form with the gluteal surface behind 



a wide, arching, supra-iliac border and 



crest. 



The ischia and pubes are always 



largely developed, and the symphysis 



is long and generally ossified. In the 

 Kangaroos the pectineal tubercle (//) 

 of the pubis is strongly developed. 



Nearly all Marsupials have a pair of 

 elongated, flattened, slightly carved 

 bones (Fig. 116, ;/v), movably articu- 

 lated by one extremity to the anterior 

 edge of the pubis, near the symphysis, 

 and, passing forwards, diverging from 

 each other, within the layers of the 

 abdominal parietes. They are, in fact, ossifications in, or 

 intimately connected with, the inner tendon or "pillar" of 

 the external oblique muscle, and therefore come under tie 



ti 



FIG. 116 Ventral surface 

 of innominate bone of 

 Kangaroo (Macropus 

 major), . si supra- 

 iliac border ; w sacral 

 surface ; is iliac sur- 

 face ; ab acetabular bor- 

 der ; pb pubic border of 

 ilium ; pt pectineal tu- 

 bercle ; a acetabulum ; 

 M/ thyroid foramen ; ti 

 tuberosity of ischium ; 

 5 symphysis ; m " mar- 

 supial " bone. 



