240 GEOGRAPHICAL ZOOLOGY. [PART iv. 



Canada and as far south as Northern Pennsylvania, and west to 

 the Mississippi (Plate XX., vol. ii. p. 135); an allied species in- 

 habiting the west coast from California to Alaska, and inland to 

 the head of the Missouri Eiver ; while a third is found in the 

 north-western part of South America ; Cercolabes (12 sp.), ranges 

 from Mexico and Guatemala to Paraguay, on the eastern side of 

 the Andes ; Chcetomys (1 sp.), North Brazil. 



Extinct Cercoldbidce. A large species of Cercolabes has been 

 found in the Brazilian caves, 'but none have been discovered in 

 North America or Europe. We may conclude therefore that 

 this is probably a South American type, which lias thence spread 

 into North America at a comparatively recent epoch. The 

 peculiar distribution of jlefaolabes may be explained by suppos- 

 ing it to have migrated northwards along the west coast by means 

 of the wooded slopes of the Rocky Mountains. It could then 

 only reach the Eastern States by way of the forest region of the 

 great lakes, and then move southward. This it may be now 

 doing, but it has not yet reached the Southern States of Eastern 

 North America. 



FAMILY 67. HYSTEICIDJi:. (3 Genera, 12 Species.) 

 GENERAL DISTRIBUTION. 



The true Porcupines have a very compact and well-marked 

 distribution, over the whole of the Oriental and Ethiopian regions 

 (except Madagascar), and the second PalaBarctic sub-region. 

 There is some confusion as to their sub-division into genera, but 

 the following are those most usually admitted : Hystrix (5 sp.), 

 South Europe to the Cape of Good Hope, all India, Ceylon, and 

 South China; Atherura (5 sp.), "brush-tailed porcupines," in- 

 habit West Africa, India, to Siam, Sumatra, and Borneo ; Acan- 

 thion (2 sp.), Nepal and Malacca, to Sumatra, Borneo, and Java. 



Extinct HystmcidpL Several extinct species of Hystrix have 



