MAMMALIA. 



83 



These little animals are exceedingly numerous in the central parts of Chile. 

 They frequent by hundreds the hedge-rows and thickets, where they make bur- 

 rows close together, leading one into another. They feed by day in a fearless 

 manner ; and are very destructive to fields of young corn ; when disturbed, they 

 all run together towards their burrows in the same manner that rabbits in England 

 do when feeding outside a covert. When running they carry their tails high up, 

 more like squirrels than rats ; and they often remain seated on their haunches, 

 like the former animals. According to Molina* they lay up a store of food for 

 the winter, but do not become dormant. The Octodon is the " degu" of that 

 author : he says that the Indians in past times used to eat them with much relish. 

 These animals appear to be very subject to be piebald and albinos ; as if partly 

 under the influence of domestication. 



Genus— ABROCOMA.1 



Dentes primores f acuti, eradicati, antice laves : molares utrinque ± subaquales, illis 

 maxillce superioris in areas duas transversales ob plicas vitreas acute indebitatus 

 divisis ; plicis utriusque lateris vix ceque profundis ; illis mandibulce inferioris in 

 tres partes divisis, plicis vitreis his interne, semel externe indentatis, area prima 

 sagittce cuspidemjingente, cceteris acute triangularibus. 



Artus subcequales. 



Antipedes 4-dactyli, externo brevissimo, intermediis longissimis etfere cequalibus. 



Pedes postici 5-dactyli; digito interno brevissimo. Ungues breves et debiles, Mo 

 digiti secundi lato et lamellari; omnibus setis rigidis obtectis. 



Caput mediocre, auribus magnis, membranaceis ; oculis mediocribus. 



Cauda breviuscula. 



Vellus perlongum, et molle. 



The genus Abrocoma is evidently allied on the one hand to the genera Octo- 

 don, Poephagomys, and Ctenomys, and on the other to the family C hinchillidce . 

 The four genera just mentioned possess so many characters in common, that it 

 would be well to unite them, and the name Octodontidce may be used to designate 

 the group. 



The Octodontidce appear to bear the same relations to Echimys, as the Arvi- 

 colw do to the Muridce. 



* Compendio de la Hist. Nat. del Eeyno de Chile, vol. i. p. 343. 

 t 'Aj3pos, soft ; K.o/xri, hair. 



