HYSTRICIDA: 



485 



(E. dorsatus), a stout heavily -built animal, with long hairs almost 

 or quite hiding the spines ; four anterior and five posterior toes ; 

 and a short stumpy tail. It is a native of the greater part of 

 Canada and the United States where there is any remnant of the 

 original forest left. Eemains of Erethizon occur in cavern-deposits 

 in Pennsylvania. 



Synetheres. 1 This genus contains some eight or ten species, 

 known as Tree Porcupines (Fig. 2 1 4), found throughout the tropical 



FIG. 214. The Tree Porcupine (Synetheres prehensilis). 



parts of South America, and one of them extending northwards into 

 Mexico. They are of a lighter build than the Ground Porcupines, 

 are covered with short, close, many-coloured spines, often mixed with 

 hairs, and their tails are always prehensile. Their hind feet have 

 only four toes, owing to the suppression of the hallux ; but they 

 have a peculiar fleshy pad on the inner side of the foot, between 

 which and the toes boughs and other objects can be firmly grasped 

 as with a hand. Vertebrae : C 7, D 17, L 5, S 3, C 36. An extinct 

 species of this genus has been described from the cavern-deposits of 

 Brazil. 



1 F. Cuvier, Mem. du Museum, vol. ix. p. 413 (1822). "Sinethere." 



