62 



MAMMALIAN DESC'EN'I'. 



[Lkct. til. 



sac, as ill some Sharks, grow into more than a tem- 

 porary union with the oviduct, or uterus, so as to cleriA'e 

 nourishment from its walls. Hence the small size of 

 the young of these creatures at hirth, the food-yolk 

 being so soon exhausted, and no other pre-natal supply 

 beino; at hand. 



Two newly-born young of the large Kangaroo 

 [Macropus major) sent to me b}^ Dr Bennett of Sydney, 

 were not so large as new-born Rats, i.e., they were, 

 about an inch long. Yet these small -Kangaroos, whose 



Fig. 8.--Ne\v-Loru youug from the poucli of Kangaroo {Macro]Jus Major), 

 magnified 2s diameters. 



parents are the size of Sheep, like the sedentary Oyster 

 "attend at ease moist nutriment," being attached to 

 the teats, and there abiding. The endnyo of the 

 Marsupial is comparable in some degree to that of 

 many fishes, in which the food-yolk is soon exhausted. 



