IV. — MAMMALIA. 29 



animals are distinguished by their having no canine teeth and 

 by having their incisors or cutting teeth large, curved and sharp. 

 The lower jaw has two of these sharp teeth ; the upper jaw in 

 some cases two and in others four. A peculiarity of these front 

 teeth is that they are not covered with enamel on the inner 

 side, so that constant use wears away the bone and maintains a 

 sharp cutting edge. Hence they are called gnawing animals. 

 Of those having two incisor teeth in the upper jaw, many speci- 

 mens are exhibited among which are : — 



SQUIRRELS— 



The Common Squirrel— (-^cmrws vulgaris). 



The Sharp-nosed Squirrel— ('S. latkaudatus) from Borneo. 

 The Bajing — (*S'. plantani) from Java. 



The Carolina Squirrel— C'S'. caroUnensis) from North America. 

 The Blackbanded Tupai— ('S'. nigrovlttatus) from Java. 



The Brazilian Squirrel— ('S^. cestivans) from Brazil. 



The Chickaree— (-S". hudsonius) from North America. 

 The Grey Squirrel— (*y. cinereus) from North America. 

 The Italian Squirrel— (-S'. italicus) from Tuscany. 



The Western Grey Squirrel — , -S*. fossor) from California. 



The Tamias — (Tamias striatus) from North America. 



Townsend's Striped Squirrel— (^am^as toionsendi) from 

 California. 



The Flying Squirrel — (Scmropterus volucella) from Canada. 



The Marmot — {Arctomys marmotta) from Switzerland. 



BEAVERS — {Castor) Northern Europe and America. 



DORMICE— 



The Dormouse — [Myoxus avellanarius) from Europe. 



RATS and MICE— 



The Common Rat— C-^iTws decumanus). 



The Common Mouse — (Mus musculus). 



The Field Mouse — {Mus sylvatkus) from Canada. 



The Alpine ArviC0le—(^ ^'vico^a nivalis) from Switzerland. 



