264 A COURSE ON ZOOLOGY. 



The dugongs attain a length of about ten feet ; the mana- 

 tees are somewhat longer. In both families the female 

 displays a remarkable affection for her young, carrying 

 it around under the nippers, with the head out of water. 

 The tail of the manatee is rounded at the end ; that of 

 the dugong is fluked. The manatee partly leaves the 

 water, even feeding on shore plants ; the dugong keeps 

 to the water, grazing on algae. 



CHAPTER XXVTII. 

 Marsupials Monotremes. 



THE females of the marsupials have the mammae placed 

 in a sac or pocket (Latin marsupium), in which the young 

 are placed after birth. This organization is necessary, 

 because the young are born in a very imperfect condition, 

 and must remain suspended at the mammae during a 

 certain term. The sac is supported by special bones, 

 called marsupial bones, which are processes from the 

 anterior portion of the pelvis ; they exist in the male as 

 well as in the female. The only species that we need 

 study are the kangaroos and opossums. 



The kangaroos live in herds on the borders of the great 

 forests of Australia. There are several species of diifer- 

 ent sizes, the largest sometimes attaining a height of 

 eight feet. The fore limbs are much shorter than the 

 posterior, and the latter, protected by a sort of hoof, are 

 the only ones used in locomotion, which in these animals 

 is very curious, consisting of a series of jumps. The long 

 tail, whose bones are very strong, acts as a sort of spring 



