CLASS mammals: order eodentia. 



95 



up hedgehog into the water ; when the frightened animal, 

 unrolling itself for an instant, will be caught by its crafty 

 enemy before it can close up again. 



Mg. 155. 



ORDER RODENTIA. 



General Characteristics. — The Eodents (gnawers) lack 

 canine teeth, but have two upper and lower incisors fitted to 

 gnaw bark, roots, woody stems, 

 nuts, etc. These are long, slightly 

 curved, chisel-edged, and deeply 

 rooted in the jaw. Friction upon 

 each other and constant growth at 

 the base keep the edges sharp.* 

 The molars are generally ridged 

 transversely and the lower jaw 

 moves backward and forward to 

 aid in mastication. Most of the order have clavicles, and 

 hence rotary motion of the fore paws, between which they 

 hold their food while gnawing. 



Skull of a Eodent. 



Q 

 O 



With 

 clavicles 



MOLAR TEETH 

 WITH HOOTS ; 



TAIL LONG, It i- i 



THINLY HAIRED. J 



Tail varying, 



SCALY. 



Tail long, 

 partially naked. 



Tail flattened, 



SCALY. 



Tail long, 

 BUSHY. 



Tail short, 



BRISTLY. 



Jumping Monte. 



Moiue, 



Without 

 clavicles ; 



MOLAR TEETH 

 WITHOUT BOOTS ; 



,f 



i GeorayidaB, GopJier. 



y CastoridEB, Beaver. 



\ SciuridE, Squirrel. 



i HystricjdEB, Porcupine. 

 Caviidse, Guinea Pig. 



[ 



Tail short, 



FURRY. 



■ Leporidie, 



Giiiti' 

 Bate. 



Jaculidae. — Jumping Mice are remarkable for their cheek- 

 pouches and long, zigzag leaps. There is but a single species 

 In N"orth America. 



* If one of the incisors be brolcen off, its opposite continues to grow, some- 

 times curving, in wliicti case at lengtti it loclis the jaw, and the wretched animal 

 etarves to death. 



5 



