MAMMALIA 617 



water, as in the duckbill. The oviducts in these animals do not 

 unite to form a vagina, but empty directly into the cloaca, which is 

 present in this subclass of mammals only. After hatching, the 

 young are nourished for a time on milk from the mammary glands 

 of the parent. These glands secrete their milk on to the hair of 

 the abdomen and the young either suck or lick it up from here. 

 There are two quite representative animals of this group. One is 

 the duckbill or duck mole, OrnitJiorhynchus anatinus, which is about 

 a foot and a half long; it is covered with hair, has webbed feet, 

 and a peculiar duck bill snout. It feeds on worms which it digs 

 from the mud with its bill. During the daytime it sleeps in its 

 grass-lined tunnel, the entrance of which is under water. The eggs 



Fig. 330. — The duckbill, Ornithorhynchus anatinus. The "duck mole" of Australia. 

 (From Metcalf, Textbook of Economic Zoology, published by Lea and Febiger.) 



are laid and the young reared in this underground chamber. On 

 the heels of the hind feet of the mole are some spurs which are sup- 

 plied with poison from a gland located in each thigh. 



A second representative of the order is the spiny anteater, Tachy- 

 glossus aculeatus, which is about one foot long and covered with 

 stiff spines mixed with coarse hair. It has a head and mouth drawn 

 out into a long proboscis with a long, slender tongue which is pro- 

 truded for picking up ants and other insects. This animal lives in 

 a burrow. 



Subclass Eutheria. — The group includes the true viviparous mam- 

 mals and is divided into two divisions, the marsupials or pouched 

 mammals (Didelphia) and the placental mammals, Monodelphia. 



