THE MIGRATIONS OF MAMMALS. 



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migrate during their waking time, namely, the bats. Defective as 

 the wing of a bat must appear when compared with that of a bird, 

 it is nevertheless of such assistance in flight, that it makes journeys 

 possible which seem out of all proportion to the size of the animal. 

 Another fact makes travelling easier to the restless bat; it is not 

 tied down by its offspring to any particular spot, for the young one 



Fig. 38. Flying Foxes. 



attaches itself directly after birth to the breast of the mother, and 

 is borne by her through the air till it is capable of independent life. 

 The bat is thus one of the best -adapted of migratory mammals, 

 and, under some circumstances, it makes full use of its advantages. 

 As a general rule, the wanderings of the different species of bat are 

 to be regarded simply as excursions made with a view to taking 

 advantage of any district which is, for the time being, particularly 

 rich in food; but they do sometimes become really long journeys, 

 which lead some species to far distant lands, and they are then not 



