72 POUCHED ANIMALS. 



83. The chief use of these tusks seems to be to aid the Morse 

 to detach from the ground and rocks the substances upon which 

 he feeds. They also serve to secure him to the rocks before he 

 trusts himself to sleep. 



84. In other respects the Morse resembles the seal, the only 

 species known inhaoits the icy ocean, and is sometimes twenty- 

 feet in length. 



LESSON VII. 



ORDER OF MARSUPIALIA. Zoological Characters. Peculiarities 

 of Organization. Habit*, (Opossums, Phalangera, Kangaroos.) 



ORDER OF RODENTIA Zoological Characters. Peculiarities of 

 their Organization. Organization and Habits of the Genus of 

 Squirrels. Squirrels properly so called, (Common Squirrel, 

 Flying Squirrel.) Organization and Habits of the Genus of 

 Hats. Marmots.- Habits. Hibernation. Dormousp. Rats 

 properly so called, (Mouse, Rat.) Hamsters. Field-mice.- 

 Jerboa. Genus of Cantors. Organization and Habits of Cas- 

 tors properly so called. Genus of Porcupines. Organization 

 and Habits o/ Porcupines properly so called. Genus of Hares. 

 Organization and Habits of Hares properly so cal'cd; (Com- 

 mon Hare, Rabbit.) Genus of Guinea-pigs. Chinchilla. 

 General remarks on Peltries. The use of Hair in the manu- 

 facture of Felt. Glue. 



1. The Marsupialia are unguiculate mammals whose different 

 organs, at the time of birth, are very imperfectly formed ; and 

 they adhere by some means to the teat of the mother until their 

 developement is accomplished. In the majority of these animals, 

 the skin of the belly forms, in front of the teats, a pouch which 

 serves to lodge the young while they are suckled ; it is from this 

 peculiarity of organization, they have obtained the name of Mar- 

 tupialia, or pouched-animals. 



2. The young, incapable of motion and almost without a dis- 

 tinct form, remain, for a certain time, fixed to the teats of the 

 mother, and concealed in the mammary pouch of which we have 

 just spoken. They do not detach themselves until they are 



83. What use does the Morse make of its tusks ? 



84. Where is the Morse found ? 



1. What are Marsupialia? What is the peculiarity of their organization 

 from which their name is derived ? 



2. During what period do the young of the Marsupials make use of the 

 mammary pouch ? How are the young of those Marsupialia that have no 

 pouch enabled to cling to their mothers ? 



