io2 THE WORLD'S LUMBER ROOM. 



Worms are found in all moderately damp countries, and 

 wherever they are they help to wear away the rocks and 

 make " dust," not only in the ways already mentioned, but 

 also by swallowing a large amount of earth and even small 

 stones, the latter of which are ground and reduced in size 

 by the process of digestion, while the former is rendered so 

 fine as to be more easily washed away by the rain. 



In some countries ants, also, do an amount of excavation 

 which may well be called enormous considering the size of 

 the workers. At Rio de Janeiro, for instance, a species 01 

 the Saiiba ant has made a tunnel under the bed of the 

 river Parahyba, where it is as wide as the Thames at London 

 Bridge ; at the Magoary rice mills, near Para, they once 

 pierced the embankment of a large reservoir; and upon 

 fumes of sulphur being blown down some of the main 

 entrances to their colonies, the smoke was seen to issue 

 from a great many outlets, one of which was seventy yards 

 away. 



Among the larger burrowers may be mentioned rabbits, 

 moles, marmots, sand-martins and other birds. In some 

 parts of Tartary, the rocks are perfectly riddled by the holes 

 of marmots, and in South America there is a small bird, 

 called by the Spaniards Casarita, or Little Householder, 

 which makes a narrow cylindrical hole nearly six feet under 

 ground, at the bottom of which it builds its nest. The holes 

 are made in any low bank of firm sandy soil, by the side of 

 a stream or road, but occasionally the birds make the 

 mistake of choosing a mud wall, and at Bahia Blanca Mr. 

 Darwin saw one which they had pierced in twenty places, 

 to the great annoyance of its owner. The wall was a low 



