1847.] JStotes on J^atural History. 253 



their burrows in the clayey portion of the soil, near those spots 

 where thrive most luxuriantly the giant thistle of the plains, upon 

 the roots of which they are supposed chiefly to exist. In general 

 appearance these animals much resemble the common rabbit, but 

 (litFer considerably in their zoological structure, and what is a re- 

 markable circumstance in their habits, is that they are universally 

 found associated with the same little burrowing owl [Athene cu- 

 niculata,) so commonly met with among the Prairie dog villages 

 in the western portion of the United States. These animals are 

 endowed with the curious propensity of picking up all hard and 

 loose substances that they occasionally meet with in their peram- 

 bulations over the plain, and conveying them to their dwellings, 

 where they may usually be seen piled up in considerable sized 

 conical heaps before their entrances. For what essential purpo- 

 ses these mounds are constructed, remains yet a subject of conjec- 

 ture, but the Indians profiting by the circumstance, frequently de- 

 stroy their symmetry in searching for small articles which at any 

 time may have been lost on the plain near their dwellings, and 

 sometimes as it was stated with complete success. 



The Agouti [Cavia Patagonica) found here, belong to the fam- 

 ily of the Guinea pigs, and greatly exceeds them all in size, be- 

 ing nearly twice the magnitude of the common hare, and w^hich 

 it much resembles when seen at a short distance peaceably hop- 

 ping over the surface of the plain in small numbers together. 

 Their legs are remarkably long, which enables them when alarm- 

 ed to make extraordinary leaps. They are exceedingly numer- 

 ous, inhabiting the burrows in common with the biscacha and 

 little owl, but when these animals do not exist in their immediete 

 neighborhood the agouti readily forms for itself habitations of a 

 very similar nature. This is likewise the case with the little 

 owl. When properly dressed these animals form an excellent 

 article of food, but is held in little repute by the wandering tribes. 



There is also a small species of armadillo found quite common 

 at this place, which is so remarkably rapid in its movements that 

 when discovered it immediately buries itself beneath the earth so 

 quickly, as to render it almost a matter of impossibility to obtain 

 them. When attacked by a dog or other animal, they roll them- 

 selves up into a ball, similar to the wood-louse, and their shells 

 being impervious to the teeth, it slips from the mouth and rolls 

 for some considerable distance over the plain. Two other spe- 

 cies are likewise found here, which differ some in their habits, 

 one at least being nocturnal. Their food consists of reptiles, in- 

 sects and vegetables. When roasted in the shell, this animal 

 furnishes a delicious repast. 



The most characteristic and interesting bird frequenting these 

 plains is the South American ostrich (Struthio rhea.) It is fre- 



