CHAPTER XXII 

 MARSUPIALS AND MONOTREMES 



BY W. b>AVILLE-KENT, F.L.S., F.Z.S. 



MARSUPIALS 



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

 and Platypus, 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 nut 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 parent 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 birth, it may be observed that a special provision commonly exists fir the early 

 nurture of the infant marsupials. In such a firm as the Kangaroo, for example, the young 

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

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

 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 in order to ensure unimpeded 

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

 commonly found thus inseparably adhering to the parent's 

 nipple has given rise to the fallacious but still very widely 

 prevalent idea among the Australian settlers that the 

 embryo marsupial is ushered into the world as a direct 

 outgrowth from the mammary region. 



At the 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 by systematic zoologists as 



lining to the Australasian 



on. What is mine, this region 



of Australasia produces, with some 



few insignificant exceptions, chiefly 



rodents, no other indigenous 



mammals n "° b *"""/*•»] 



' .' . . SILVER-GREY KANGAROO 



It is interesting to note that , , , ,. . 



Jn general form the kangaroo* are to like one another that one pgurc would almost serve 



within the limits of this isolated for all 



308 



