A REMARKABLE MAMMAL 185 



wood till it opens up the tunnel of the burrowing 

 larva. As soon as the tunnel is reached the attenuated 

 middle finger is thrust in, either to act as a probe to 

 determine the position of the larva, or to drag it out from 

 its hiding-place, or perhaps for both purposes. Some un- 

 certainty still obtains as to the exact details of these and 

 other operations of a like nature, for our information on 

 these points appears to be mainly, if not exclusively, based 

 on native accounts. There is, however, little doubt that 

 the modus operandi is in the main as described above. 



We thus have a sufficient and satisfactory explanation 

 of the reason why the aye-aye differs so remarkably in its 

 dentition and in the structure of its hand from all its living 

 kindred. If, however, we attempt to account for the gradual 

 development of these peculiarities by what is commonly called 

 natural selection, we encounter considerable difficulty. It is 

 easy to conceive how the ancestors of the horse lost their 

 lateral toes by disuse, but how an ancestral aye-aye gradually 

 reduced the size of its middle finger till it assumed the 

 attenuated proportions of its existing representative is very 

 hard to understand, seeing that a slight diminution in the 

 calibre of this digit would be of little or no advantage. 

 Some much more potent cause than " natural selection " 

 seems necessary in this, as in many other instances. 



As regards its general mode of life, the aye-aye wanders 

 through the silent forest at night in pairs, and never appears 

 to associate with others of its fellows than its partner. Pro- 

 bably the partnership is for life, but on this point we have 

 no definite information. The aye-aye is one of the com- 

 paratively few mammals which build a regular nest ; this 

 being constructed, according to Mr. Baron, of the carefully 

 rolled up leaves of one particular kind of tree, and lined 

 with small twigs and dry leaves ; the whole structure having 



