THE VOYAGE OF THE BEAGLE 305 



occurs: but in the Chonos Islands, three degrees farther 

 southward, we have seen that it is abundant. On the eastern 

 coast in La Plata (lat. 35) I was told by a Spanish resident 

 who had visited Ireland, that he had often sought for this 

 substance, but had never been able to find any. He showed 

 me, as the nearest approach to it which he had discovered, a 

 black peaty soil, so penetrated with roots as to allow of an 

 extremely slow and imperfect combustion. 



The zoology of these broken islets of the Chonos Archi- 

 pelago is, as might have been expected, very poor. Of quad- 

 rupeds two aquatic kinds are common. The Myopotamus 

 Coypus (like a beaver, but with a round tail) is well known 

 from its fine fur, which is an object of trade throughout the 

 tributaries of La Plata. It here, however, exclusively fre- 

 quents salt water; which same circumstance has been men- 

 tioned as sometimes occurring with the great rodent, the 

 Capybara. A small sea-otter is very numerous; this animal 

 does not feed exclusively on fish, but, like the seals, draws a 

 large supply from a small red crab, which swims in shoals 

 near the surface of the water. Mr. Bynoe saw one in Tierra 

 del Fuego eating a cuttle-fish ; and at Low's Harbour, another 

 was killed in the act of carrying to its hole a large volute 

 shell. At one place I caught in a trap a singular little mouse 

 (M. brachiotis) ; it appeared common on several of the islets, 

 but the Chilotans at Low's Harbour said that it was not found 

 in all. What a succession of chances,* or what changes of 

 level must have been brought into play, thus to spread these 

 small animals throughout this broken archipelago ! 



In all parts of Chiloe and Chonos, two very strange birds 

 occur, which are allied to, and replace, the Turco and Tapa- 

 colo of central Chile. One is called by the inhabitants 

 "Cheucau" (Pteroptochos rubecula) : it frequents the most 

 gloomy and retired spots within the damp forests. Some- 

 times, although its cry may be heard close at hand, let a per- 

 son watch ever so attentively he will not see the cheucau ; at 



* It is said that some rapacious birds bring their prey alive to their 

 nests. If so, in the course of centuries, every now and then, one might 

 .escape from the young birds. Some such agency is necessary, to account 

 for the distribution of the smaller gnawing animals on islands not very 

 near each other. 



