XVII.] 



MARSUPIALIA. 



325 



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 curved 



bones (Fig. 116, m\ movably articu- 

 lated by one extremity to the anterior 



edge of the pubis, near the symphysis, 



and, passing forwards, diverging from * symphysis: m -mar- 



supial bone. 



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 the 



ti 



FIG. 116 Ventral surface 

 of innominate bone of 

 Kangaroo (Mncropus 

 major), J. si supra- 

 iliac border ; ss sacral 

 surface ; is iliac sur- 

 face ; al> acetabular bor- 

 der ; pb pubic border of 

 ilium ; // pectineal tu- 

 bercle ; a acetabulum ; 

 ////"thyroid foramen ; //' 

 tuberosity of ischium ; 



