CHAPTER XXII. 



MARSUPIALS AND MONOTREMES. 



liV W. SAVILLE-KENT, F.L.S., F.Z.S. 



MARSUPIALS. 



WITH the order of the Pouched Mammals we arrive— with the exception of the Echidna 

 and Platyiius, next described — at the most simply organised representatives of the 

 Mammalian Class. In the two forms above named, egg-production, after the manner 

 of birds and reptiles, constitutes the only method of propagation. Although among marsupials 

 so rudimentary a method of reproduction is not met with, the young are brought into the 

 world in a far more embryonic condition than occurs among any of the mammalian groups 

 previously enumerated. There is, as a matter of fact, an entire absence of that vascular or blood 

 connection betwixt the })arent and young previous to birth, known as placentation, common 

 to all the higher mammals, though certain of the more generalised forms have been recently 

 found to possess a rudiment of such development. In correlation with their abnormally 

 premature l)irth, it may be observed that a special provision commonly exists for the early 

 nurture of the infant marsuj^ials. In such a form as the Kangaroo, for example, the young 

 one is placed, through the instrumentality of its parent's lips, in contact with the food-supplying 

 teat, and to which for some considerable period it then becomes inseparably attached. SiDecial 

 muscles exist in connection with the parent's mammary 

 glands for controlling the supply of milk to the young 

 animal, while the respiratory organs of the little creature 

 are temporarily modified m order to ensure unimpeded 

 respiration. The fact of the young in their early life being 

 commordy found tluis inseparably adhering to the parent's 

 nipple lias given rise to the falacious but still very widely 

 virevalent idea among the Australian settlers that the 

 embrj'o marsupial is ushered into the world as a direct 

 outgrowth from the mammary region. 



At tlie present day, with the exception of 

 the small group of the American Opossums and 

 the Selvas, the entire assemblage of marsupials, 

 comprising some 36 genera and 150 species, 

 are, singularly to relate, exclusively 



found in Australia, New Guinea, and 

 the few neighbouring islands recog- 

 nised l)y systematic zoologists as 

 pertaining to the Australasian 

 region. \\'hat is more, this region 

 of Australasia produces, with some 

 few insignificant exceptions, chiefly 

 rodents, no other indigenous 



o 



mammals. 



It is interesting to note that 

 within the limits of this isolated 



riiiilnh,/ hill, n/tun] 



STL^ ER r,EI \ 



ll^iui^dsland. 



Ii] f^erier;i] form the k.angarno..; iire s 

 ?A4 



like nne iinother that uno fiL:tiro woulil almost serve 

 for all. 



