ORDER RODENTIA. 117 



The subgenus Echimys, or Spiney Rats, (Loncheres, Uli- 

 ger,) was established by M. Geoffroy St. Hilaire, principally 

 on the character from which it is named, the back being fur- 

 nished with spines as well as hair. Their teeth offer some 

 slight variation from their congeners, as may be seen in the 

 text. Their general form approaches that of the Rats ; the 

 body elongated ; the tail varying in length in the different 

 species, but always round and generally scaly ; the anterior 

 paws have four toes and the rudiment of a thumb, those 

 behind have five, and all of them are armed, with bent, dig- 

 ging claws. It does not appear that all the Spiny Rats 

 are included in this subdivision, as the Perchal and the 

 Mus Cahirinus of Geoffroy are referred to the Rats proper. 



M. d'Azara has furnished us with some particulars of 

 the Red Echimys, and as all that is published of the re- 

 maining species of this subdivision is confined to their phy- 

 sicalities, it may be sufficient to refer to the Table for a brief 

 account of their specific characters. 



This animal is about eight inches long, with a tail not 

 exceeding three. On the head, sides, body, and flanks? the 

 colour is a mixture of dark brown and reddish ; the under 

 parts are white, and the tail covered with short hair, thick 

 and soft, through which the scaly skin cannot be seen, is of 

 a dark brown colour. The longest spines are about nine 

 lines in length, formed like a double-edged sword ; they are 

 whitish for about two-thirds their length ; whitish-brown 

 toward the point. 



In general, the head, neck, and body, are thicker than in 

 the common Rat. The male is rather larger than the female. 

 The Red Echimys is found at Cayenne, Paraguay, and espe- 

 cially between the town of Neemboucon and the river Plate. 

 They dig their burrows in dry and sandy soils, and they are 

 dug so close to each other as to make much precaution 

 necessary in walking over them ; they are about four or five 

 feet long, and about eight inches under the surface. 



