438 MAMMALIA. 



are no teeth in Echidna, whilst the duck-bill has four horny 

 pads in their place. The pectoral arch is like that of Saurop- 

 sids — namely, the coracoid hones reach the sternum, and an 

 interclaviole is present. The pelvis is furnished with special 

 tendinous ossifications, forming the peculiar " marsupial hones,'' 

 although the female carries no pouch as in the marsupial animal. 

 The Monotremes come from Australia, Tasmania, and New 

 Guinea. The females have no nipples to the mammae, and lay 

 eggs covered by a flexible shell. These are the only oviparous 

 mammals. 



B. DIDELPHIA 



= METATHERIA. 



Order— MARSUPIALIA or POUCH-BEARERS. 



No marsupial animals exist in Europe. Their present 

 geographical distribution is very limited : the majority are 

 found in Australia and the adjacent islands, where the entire 

 indigenous fauna is marsupial. A few species (Opossums) are 

 found in America and others in the Indian Archipelago (Mac- 

 ropus, Cuscus, &c.) The "Pouch-Bearers" have distinct teeth 

 placed in sockets, and the angle of the lower jaw is nearly 

 always inflected. A "marsupial bone" is always present 

 attached to the edge of the pelvis : its function in the female 

 is to act as a support for the pouch and to aid the action of the 

 mammae. In the males, which have no pouch, it may he in 

 some way connected with the testes. The " marsupium " or 

 " pouch '' is always present in the female, and has the nipples of 

 the mammae inside it : in this pouch the young, which are born 

 in an immature state, are carried for some time by the mother. 

 The long mammae force their way into the young marsupial's 

 mouth without its aid ; as soon as they can suck naturally, they 

 leave the pouch and return to it for nourishment whenever they 

 require it. A peculiarity in the male is that the testes, which 

 are in a scrotum, are situated in front of the penis and not 



