184 



LAND MAMMALS IN THE WESTERN HEMISPHERE 



thizon) represents it, and that is a late immigrant from the 

 south. 



It would lead us too far to attempt a description of this 

 horde of curious and interesting rodents, so only a few of the 

 more striking and characteristic forms can be mentioned. 

 There are two genera of porcupines {Coendou and Chcetomys), 

 both arboreal, which belong in the same family as the North 

 American Erethizon, but are distinguished by their long, 

 prehensile tails, which they use, as monkeys and opossums 



Fig. 105. — Chinchilla {Chinchilla laniger). — By permission of W. S. Berridge, London. 



do, for grasping and climbing. The very large family of the 

 Octodontidse has 17 Neotropical genera and four others are 

 found in Africa. The Degu (Octodon) of ChiU, Bolivia and 

 Peru has the appearance of a large rat with tufted tail ; the 

 tuco-tucos (Ctenomys) are extremely abundant burrowers in 

 Patagonia, where they honeycomb the ground over wide areas. 

 The spiny rats {Echimys and Loncheres) are so called from their 

 appearance, not because they are related to the true rats ; 

 they have numerous horny spikes through the fur of the back. 

 The Coypu (Myocastor) is a large, aquatic animal, remotely 

 like the northern Muskrat, and the Hutias (Capromys and 



