128 PRIMITIVE ANIMALS 



undeveloped state while they are still exceedingly 

 small ; thus the newly born young of a kangaroo, 

 which when adult measures upward of six feet high, 

 is less than half-an-inch in length when first delivered 

 by the mother, and it is still in the developmental 

 stage of a very early foetus of OTO of the higher 

 Mammals. After delivery, the mother picks up the 

 tiny foetus with her lips and transfers it to her pouch, 

 placing the lips of the foetus on to one of the nipples 

 which are enclosed in the pouch. The lips of the 

 foetus become firmly fixed to the nipple, and here it 

 is suckled by the mother for a very long period until 

 it is about a quarter full grown. The discovery of the 

 minute foetus attached to the nipple of the mother 

 led to the idea, which is still current among the 

 settlers in Australia, that the young are actually 

 born in this situation, a supposition so grotesquely 

 at variance with all the facts of Mammalian anatomy 

 and physiology as hardly to deserve the minute and 

 circumstantial refutation it has naturally received. 



The birth of the Marsupial young in so small, 

 helpless and undeveloped a condition, as compared 

 with the young of an ordinary Mammal, is due to 

 the comparatively inferior nutrition of the embryo 

 while still in the uterus of the mother. The Mar- 

 supial embryo is in fact half-way between the 

 condition of the Monotreme, where the embryo is 

 delivered as an egg and is entirely dependent on 



