Mode of Generation of the Kangaroo. 231 
muscles, and adheres firmly to each of the mammae ; this 
muscle, when the young is sucking, will prevent the mamma 
being dragged from its natural situation. 
The two bones which lie behind the mammae deserve a par- 
ticular description, as they are peculiar to the opossum tribe, 
and belong to the mammae, and false belly, having no other 
apparent use but what is connected with the motion of these 
parts. 
They are about two inches and an half long, are flattened, 
and at their broadest part measure nearly half an inch ; they 
are attached to a projecting part of the os pubis, fitted for that 
purpose,just before the insertion of the recti abdominis muscles ; 
this attachment to the pubis is by a very small surface, and 
admits of considerable motion ; they have likewise a connec- 
tion by a ligament half an inch in breadth, to the ramus of 
the pubis, which joins the ilium. From their base, which is 
united to the pubis in these different ways, they become nar- 
rower till they terminate in a blunted point. These bones 
have a pair of muscles inserted into their base, to bring them 
downwards and outwards ; another pair into their blunted ex- 
tremities to bring them forwards ; a pair of broad flat muscles 
fill up the whole space between them, arising from their inner 
edge through its whole length ; they serve as a sling to support 
the mammae, and also to bring the bones towards each other. 
Besides these additional bones, and the projection to which 
they are attached, there is another peculiarity in the structure 
of the pelvis of the female kanguroo ; the two rami of the os 
ischium which join the pubis, have no notch between them as 
in other quadrupeds, but form a rounded convex surface of 
some breadth, projecting considerably forwards ; the surface 
H h 2 
