﻿MARSUPIALS IN GENERAL. 7 



its name, the only exceptions to this rule being the instances 

 where the pouch itself is absent. Showing at first but little 

 signs of life, the young Marsupials hang on to the nipples of 

 their parents till they have attained a state of development 

 permitting them to move and perform the other ordinary 

 functions of life ; they may, however, as among the Kan- 

 garoos, still make use of the pouch as a place of refuge till 

 they attain dimensions which prohibit their entrance. It will 

 be inferred from the above that the placenta or vascular organ 

 connecting the blood-vessels of the foetus with those of the 

 parent in the higher Mammals is totally wanting among the 

 Marsupials, whence they are often spoken of as Implacentals, 

 in contradistinction to the Placentals, or higher Mammals. 

 With the exception of the Thylacine, where they are rudi- 

 mentary, Marsupials are further characterised by the presence 

 of a pair of so-called marsupial, or epipubic bones, attached 

 to the front edge of the middle of the lower part of the pelvis. 

 It was at one time supposed that these bones bore some special 

 relation to the pouch, but, since they are present in both sexes, 

 it is obvious that such cannot be the case. 



Among other features common to all Marsupials, it may be 

 mentioned that the brain is relatively very small in proportion 

 to the size of the head and body, while its external surface 

 exhibits comparatively few foldings and convolutions ; thus 

 indicating that the brain-power and general intelligence of 

 these creatures is of a low grade. Another indication of their 

 low organisation is afforded by the structure of the uterus of 

 the female, which is double throughout its length, whence the 

 name of Didelphia has been applied to the group. Another 

 very characteristic feature is the inward inclination or inflec- 

 tion of the lower border of the angle, or hinder extremity of the 

 inferior edge, of the lower jaw. 



In all cases there are two pairs of limbs, which are normal 



