CHAP. XVIL] MAMMALIA. 239 



of Panama. The genera are as follows: Dactylomys (2 sp.), 

 Guiana and Brazil ; Cercomys (1 sp.), Central Brazil ; Lasiuromys 

 (1 sp.), San Paulo, Brazil; Petromys (1 sp.), South Africa; Myopo- 

 tamus (1 sp.), the coypu, on the East side of the Andes from 

 Peru to 42 S. lat., on the West side from 33 to 48 S. lat. ; 

 Carterodon (1 sp.), Minaes Geraes, Brazil ; Aulacodes (1. sp.), 

 West and South Africa ; Mesomys (1 sp.), Borba on the Amazon ; 

 EcJiimys (11 sp.), from Guiana and the Ecuadorian Andes to 

 Paraguay ; Loncheres (10 sp.), New Granada to Brazil. 



Fossil and Extinct Echimyido3. The genus Carterodon was 

 established on bones found in the Brazilian caves, and it was 

 several years afterwards that specimens were obtained showing 

 the animal to be a living species. Extinct species of Myopo- 

 tamus and Loncheres have also been found in these caves, with 

 the extinct genera Lonchophorus and Phyllomys. 



No remains of this family have been discovered in North 

 America ; but in the Miocene and Upper Eocene deposits of 

 France there are many species of an extinct genus Theridomys, 

 which is said to be allied to this group or to the next (Cercola- 

 bidse). Aulacodon, from the Upper Miocene of Germany, is 

 allied to the West African Aulacodes ; and some other remains 

 from the lower Miocene of Auvergne, are supposed to belong to 

 Echimys. 



FAMILY 66. OERCOLABTD^. (3 -Genera, 13-15 Specips.) 

 GENERAL DISTRIBUTION. 



The Cercolabidse, or arboreal porcupines, are a group of rodents 

 entirely confined to America, where they range from the northern 

 limit of trees on the Mackenzie Eiver, to the southern limit of 

 forests in Paraguay. There is however an intervening district, 

 the Southern United States, from which they are absent. Ere- 

 tliizon (3 sp.), the Canadian porcupine, is found throughout 



