PATAGONIAN CAVY. 151 



line, over plains of gravel thinly clothed with a few 

 thorny dreary bushes and a withered herbage. 



According to Azara, this cavy does not range higher 

 north than latitude 35° : but in this statement he appears 

 to be mistaken, for Mr. Darwin observed that near the 

 coast of the Atlantic its northern limit is formed by the 

 Sierra Tapalguen, in latitude 37° 30', where the plains 

 rather suddenly become greener and more humid ; and 

 he remarks that its limit there certainly depends on this 

 change, since near Mendoza, 33° 30', four degrees far- 

 ther northward, where the country is very sterile, this 

 animal again occurs. Azara states that this cavy never 

 excavates its own burrow, but always uses that of the 

 viscacha or biscacha ; and Mr. Darwin considers that 

 where that animal is present Azara's statement is doubt- 

 less correct, but that on the sandy plains of Bahia Blanca, 

 where the biscacha is not found, this cavy, as the Spa- 

 niards maintain, is its own workman. The same thing, 

 he adds, occurs with the little owls of the Pampas (noctua 

 cunicularid) ^ which have been described by travellers as 

 standing like sentinels at the mouth of almost every 

 burrow; for in Banda Oriental, owing to the absence 

 of the biscacha, these birds are obliged to hollow out 

 their own habitations. Azara moreover states that, 

 except when pressed by danger, this cavy does not have 

 recourse to its burrow for safety, but crouches on the 

 plains, or trusts to its speed ; adding, however, that it is 

 soon run down. On the contrary, Mr. Darwin asserts 

 that at Bahia Blanca he repeatedly saw two or three 

 animals sitting on their haunches by the mouths of their 

 holes, which they quietly entered as he passed by at a 

 distance. He remarks, however, that, different from 

 most burrowing animals, they wander, commonly two or 

 three together, to miles or even leagues from their home, 

 and he was not able to ascertain whether or not they re- 

 turned at night. This species is diurnal in its habits, 

 roaming about by day. It is very shy and watchful, 

 seldom squats after the manner of a hare, and cannot run 

 fast, so that indifferent dogs easily overtake it. The 

 female breeds in her burrow, generally producing two 



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