MAJUMALIA 



457 



Order Rodentia (gnawing animals). — Rodents are small 

 mammals with clawed digits. They have no canine teeth, 

 but have well-developed chisel-shaped incisors which continue 

 to grow as they are worn at the extremity. The chisel edge is 

 preserved by the fact that the enamel is chiefly in front, and 



Fig. 240. 



Fig. 240. The Fox Squirrel {Sciurtts iii^cr rufivmilcr). Photographed by Folsora. 



Fig. 241. 



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Fig. 241. Porcupine (Erethizon). By Dr. J. W. Folsom. 



Questions on the figure. — To what order of mammals does the porcupine 

 belong? What are its peculiarities of habit and structure? 



the exposed, softer dentine behind is worn away more rapidly 

 by being used. The brain is smooth. The mammae are ab- 

 dominal. Rodents have world-wide distribution, and are 



