304 



ZOOLOGY. 



424. The order marsupialia is chiefly characterized by 

 the presence of a sort of pouch, destined to hold the young 

 whilst attached to the nipple, and during the early period of 

 their growth. A description of this pouch, with a drawing 

 of the form of the marsupial bones, will be found in Fig. 194. 

 The food of the marsupialia is various, some being insectivo- 

 rous, others herbivorous, others carnivorous, whilst some 

 strongly resemble the class rodents. They nearly all belong to 

 Australia and Tasmania. The opossums (Fig. 194), the 

 phalangers, and the kangaroos (Fig. 280), chiefly represent 

 the group. 



--^rrsit / 



Fig. 281. The Oniithorynchus. 



425. Finally, the order called monotremes seems to 

 connect the mammal with the oviparous vertebrata. The 

 intestine terminates, as in birds, in a cloaca, and the repro- 

 ductive organs present many anomalies. The dental system 

 is rudimentary, and in some a horny covering of the jaws 

 gives to them the appearance of a duck's bill. As yet only 

 two genera of this singular class is known ; the ornitho- 

 rynchus (Platypus, or duck-billed animal) (Fig. 281), and 

 the echidna. 



