BATS. 13 



the amount of earth-movements which it must necessarily have 

 entailed. Although we are averse to calling in such movements 

 unnecessarily, we confess that, in our opinion, his theory does 

 not account for the poverty of the Mammalian fauna of Ireland 

 as compared with that of the rest of Britain in the perfect 

 manner in which that of Mr. Wallace does; and until this 

 is done we prefer to incline towards the latter, which, it must 

 be remembered, is to a considerable extent supported by the 

 submerged forests and ancient deserted river-channels of Eng- 

 land. 



Whether, however, the one theory or the other of the re- 

 population of England be adopted, we have to remember that 

 the present impoverished Mammalian fauna of Britain, as com- 

 pared with the Continent, is due to the direct or indirect 

 action of the Glacial period, the effects of which have been so 

 far-reaching both on inanimate and animate nature in the 

 Northern Hemisphere. 



THE BATS. ORDER CHIROPTERA. 



The special modification of the bones of the fore-limb for 

 the purpose of flight, coupled with the presence of a leathery 

 flying-membrane extending from the front of the fore-limb, 

 connecting together the toes, or fingers, of the same, then 

 joining the hind-limbs, and likewise connecting together the 

 two latter, with or without the intervention of the tail, at once 

 serves to distinguish sharply the Bats from all other members 

 of the Mammalian class. They are likewise the only Mammals 

 endowed with the power of true flight, like birds; the long 

 flying leaps of the Flying Squirrels and the Flying Phalangers 

 being nothing more than a prolongation of an ordinary leap by 

 the aid of a parachute-like expansion of the skin of the flanks, 

 without any special modification or elongation of the bones of 

 the fore-limbs. 



Referring in some detail to the structure of the fere-limb, 



