110 HABITS AND INSTINCTS OF ANIMALS. CHAP. IV. 



motion almost unique among animals. In the con- 

 struction of its remarkable dwelling, it was necessary 

 that the soft mud and clay which it employs should be 

 rendered compact : hence it is supplied with a broad 

 and powerful tail, which is used in the same manner, 

 to accomplish this object, as is a trowel in the hands 

 of a bricklayer. As we shall have to mention other 

 singularities of this interesting animal in another place, 

 it will be sufficient to allude, at present, to its power of 

 swimming with the greatest facility. The hedge- 

 hog, and a few other quadrupeds of the same type, 

 present us with a sort of motion only to be found 

 among them, and certain insects which they represent. 

 As they have but little speed to escape from their 

 enemies, they are not only covered with defensive 

 spines, but have the power of rolling themselves up 

 like a ball ; and, by erecting the bristles with which they 

 are covered, present themselves, armed at all points, to 

 their enemies. 



(131.) The only quadrupeds, however, which really 

 fly, are the bats ; they compose a large family, scat- 

 tered over all temperate and tropical countries, and 

 varying, according to the species, from the size of a 

 kitten to less than a harvest mouse. We have already 

 had occasion, under the head of Instinct, to speak of 

 the astonishing powers they possess in directing their 

 course through the most perplexing windings ; while 

 their flight, when pursued without such impediments, 

 is well known to be as swift, if not more so, than 

 swallows. A popular belief was long held, that these 

 animals could not mount into the air, if once they 

 came upon a flat surface ; but this error was long 

 ago refuted by White of Selborne, who says that one 

 he had in confinement " rose with great ease from the 

 floor," and " ran with more despatch than I was aware 

 of, but in a most ridiculous and grotesque manner." * 

 We can confirm the latter, but not the former, state- 

 ment. Two bats, of the common species, which we 

 Nat. Hist, of Selborne, voL i. p. 57. 



