i6o 



MARSUPIALIA 



consists of sharp -edged incisors, most fully developed near the 

 median line of the mouth, for the purpose of cropping the various 

 kinds of herbage on which they feed, and ridged and tuberculated 

 molars for crushing it, there being no tusks or canines for offensive 

 or defensive purposes. 



The number of vertebrae is in the cervical region 7, dorsal 13, 

 lumbar 6, sacral 2, caudal varying according to the length of the 

 tail, but generally from 21 to 25. In the fore limb the clavicle 

 and the radius and ulna are well developed, allowing of considerable 

 freedom of motion of the hand. The pelvis has large epipubic or 

 " marsupial " bones. The femur is short, and the tibia and fibula 



FIG. 53. The Great Gray Kangaroo (Macropus giganteus). 



are of great length, as is the foot, the whole of which is applied to 

 the ground when the animal is at rest in the upright position. 



The stomach is of large size, and very complex, its walls being 

 puckered up by longitudinal muscular bands into a great number of 

 sacculi, like those of the human colon. The alimentary canal is 

 long, and the caecum well developed. All the species have a 

 marsupium or pouch formed by a fold of the skin of the abdomen, 

 covering the mammary glands with their four nipples. In this 

 pouch the young are placed as soon as they are born ; there their 

 growth and development proceeds ; and to it they resort tempor- 

 arily for the purpose of shelter, concealment, or transport, for some 

 time after they are able to run and jump about the ground and 

 feed upon the same herbage which forms the nourishment of the 

 parent. During the early period of their sojourn in the pouch, 



