THE VOYAGE OF THE BEAGLE 61 



gallop with the greatest impetuosity, and emitted at the 

 same time their bark. After diving a short distance they 

 came again to the surface, but only just showed the upper 

 part of their heads. When the female is swimming in the 

 water, and has young ones, they are said to sit on her back. 

 These animals are easily killed in numbers ; but their skins 

 are of trifling value, and the meat is very indifferent. On 

 the islands in the Rio Parana they are exceedingly abundant, 

 and afford the ordinary prey to the Jaguar. 



The Tucutuco (Ctenomys Brasiliensis) is a curious small 

 animal, which may be briefly described as a Gnawer, with 

 the habits of a mole. It is extremely numerous in some 

 parts of the country, but it is difficult to be procured, and 

 never, I believe, comes out of the ground. It throws up at 

 the mouth of its burrows hillocks of earth like those of the 

 mole, but smaller. Considerable tracts of country are so 

 completely undermined by these animals, that horses in pass- 

 ing over, sink above their fetlocks. The tucutucos appear, 

 to a certain degree, to be gregarious : the man who pro- 

 cured the specimens for me had caught six together, and he 

 said this was a common occurrence. They are nocturnal in 

 their habits; and their principal food is the roots of plants, 

 which are the object of their extensive and superficial bur- 

 rows. This animal is universally known by a very peculiar 

 noise which it makes when beneath the ground. A person, 

 the first time he hears it, is much surprised; for it is not 

 easy to tell whence it comes, nor is it possible to guess what 

 kind of creature utters it. The noise consists in a short, but 

 not rough, nasal grunt, which is monotonously repeated 

 about four times in quick succession : 8 the name Tucutuco is 

 given in imitation of the sound. Where this animal is 

 abundant, it may be heard at all times of the day, and some- 

 times directly beneath one's feet. When kept in a room, the 

 tucutucos move both slowly and clumsily, which appears 

 owing to the outward action of their hind legs ; and they are 



At the R. Negro, in Northern Patagonia, there is an animal of the 

 same habits, and probably a closely allied species, but which I never saw. 

 Its noise is different from that of the Maldonado kind; it is repeated only 

 twice instead of three or four times, and is more distinct and sonorous; 

 when heard from a distance it so closely resembles the sound made in cut- 

 ting down a small tree with an axe, that I have sometimes remained in 

 doubt concerning it. 



