xii PHYLUM CHORDATA 519 



most of the sutures remaining distinguishable throughout 

 life ; the coracoid is represented by vestiges, and an epis- 

 ternum is absent as a distinct bone. The early development 

 of the young takes place in the uterus. 



Of the Theria again, there are two sections, the Metatheria 

 or Marsupialia and the Eutheria. 



The section Metatheria comprises all the pouch-bearing 

 Mammals or Marsupials, such as the Opossums, the 

 Dasyures, the Bandicoots, the Wombats, the Phalangers, 

 and the Kangaroos nearly all, with the exception of the 

 Opossums, confined to the Australian region. They are 

 characterised by the possession of a pouch or marsupium 

 within which the young, born in a rudimentary and helpless 

 condition, are sheltered. They also, like the Prototheria, 

 possess a pair of peculiar bones, the epipubic or marsupial 

 bones, attached to the pubes. 



In the Eutheria marsupium and marsupial bones are 

 absent. This section comprises the great majority of 

 Mammals, which, when the fossil forms are left out of 

 account, are capable of being arranged in nine orders : 



1. Edentata, comprising the Sloths, Ant-eaters and 

 Armadillos. 



2. Cetacea, including the Whales, Porpoises, and Dolphins. 



3. Sirem'a, or Dugongs and Manatees. 



4. Ungulata : a very large order, comprising among 

 others, the Horser, Tapirs, and Rhinoceroses, the Ruminants 

 (Camels, Oxen, Sheep, Goats, Antelopes, Giraffes, and Deer), 

 the Pigs and Hippopotami, the Hyraxes, and the Elephants. 



5. Carnivora, or the Cats, Dogs, Bears, Weasels, and 

 Otters, and the Seals and Walruses. 



6. Rodentia : a large order, including, among many 

 others, the Rats and Mice, Hares and Rabbits, Squirrels, 

 Beavers, and Porcupines. 



