60 CHARLES DARWIN 



north of Scotland treat the rank carcasses of the fish-eating 

 birds in the same manner. 



The order Rodentia is here very numerous in species: 

 of mice alone I obtained no less than eight kinds.* The 

 largest gnawing animal in the world, the Hydrochserus capy- 

 bara (the water-hog), is here also common. One which I 

 shot at Monte Video weighed ninety-eight pounds: its 

 length, from the end of the snout to the stump-like tail, was 

 three feet two inches; and its girth three feet eight. These 

 great Rodents occasionally frequent the islands in the mouth 

 of the Plata, where the water is quite salt, but are far more 

 abundant on the borders of fresh-water lakes and rivers. 

 Near Maldonado three or four generally live together. In 

 the daytime they either lie among the aquatic plants, or 

 openly feed on the turf plain. 6 When viewed at a distance, 

 from their manner of walking and colour they resemble pigs : 

 but when seated on their haunches, and attentively watch- 

 ing any object with one eye, they reassume the appearance 

 of their congeners, cavies and rabbits. Both the front and 

 side view of their head has quite a ludicrous aspect, from 

 the great depth of their jaw. These animals, at Maldonado, 

 were very tame ; by cautiously walking, I approached within 

 three yards of four old ones. This tameness may probably 

 be accounted for, by the Jaguar having been banished for 

 some years, and by the Gaucho not thinking it worth his 

 while to hunt them. As I approached nearer and nearer 

 they frequently made their peculiar noise, which is a low 

 abrupt grunt, not having much actual sound, but rather aris- 

 ing from the sudden expulsion of air : the only noise I know 

 at all like it, is the first hoarse bark of a large dog. Having 

 watched the four from almost within arm's length (and they 

 me) for several minutes, they rushed into the water at full 



* In South America I collected altogether twenty-seven species of mice, 

 and thirteen more are known from the works of Azara ana other authors. 

 Those collected by myself have been named and described by Mr. Water- 

 house at the meetings of the Zoological Society. I must be allowed to take 

 this opportunity of returning my cordial thanks to Mr. Waterhouse, and 

 to the other gentlemen attached to that Society, for their kind and most 

 liberal assistance on all occasions. 



B In the stomach and duodenum of a capybara which I opened I found 

 a very large quantity of a thin yellowish fluid, in which scarcely a fibre 

 could be distinguished. Mr. Owen informs me that a part of the oesophagus 

 is so constructed that nothing much larger than a crowquill can be passed 

 down. Certainly the broad teeth and strong jaws of this animal are well 

 fitted to grind into pulp the aquatic plants on which it feeds. 



