408 



ORDERS OF MAMMALIA. 



of living Rodents which are principally South American and 

 African (Ododon, Echimys, Ctenomys, &c.) 



The most important extinct type of this family is the 

 Theridomys of the Eocene and Miocene of Europe, and of the 

 Eocene of South America (fig. 683, b), which is allied to the 

 living Spiny Rats {Echimys), and also has points of relation- 

 ship with the Beavers. The Megamys of the South American 

 Eocene and the Palamnys of the Miocene of Europe are, fur- 

 ther, believed to be related to the living Capromys of the 

 West Indies. Lastly, the genus Ctenomys occurs in the 

 Pliocene of South America ; and the bone-caves of Brazil 

 have yielded remains of Echimys, together with a species of 

 Coypu {Myopotamus). 



Eam. 7. ChincMllidcc. — This family includes some South 

 American Rodents, of which the true Chinchillas (Chinchilla) 

 are the best known. Tliey are small nocturnal animals, 

 strictly terrestrial in their habits, and liaving the hind-legs 

 considerably longer than the fore-legs. 



We may, perhaps, place in this family the extinct genus 

 Archceomys (fig. 683, a) from the Miocene of France. 



& B 



Fig. 683. ^A, Lower molars of Archceomys rhinchiUoUhs — Mioeene, France ; b, Upper 

 molars of Theridomys Lembronica — Miocene, France ; c, Lower molars of Chalicomys Jcpgcri — 

 Miocene, Germany ; d, Left ramus of lower jaw of Titanomys Visenoviensis — Mioeene, France ; 

 E, Two lower molars of the living Lemming (Lcmm.vs Norvegiciis) ; f, Lower molars of the 

 living Paca (Cwlogenys paca) ; o, One of the lower molars of the li\'ing Beaver (Castor fiber). 



Species of Viscacha (Lagostomus) have also been found in 

 the Pliocene and Post-Pliocene deposits of South America ; 

 and the cave-deposits of Anguilla in the West Indies have 

 yielded the remains of the extinct genera Amhlyrhiza and 

 Loxomylus. 



