346 Wortynan — Studies of Eocene Mammalia m the 



then, again, the second finger of the hands is unlike anything 

 but a monster supernumerary member, it being slender and 

 long, half the thickness of the other fingers, and resembling a 

 piece of bent wire. Excepting the head and this finger, he 

 closely resembles a Lemur. 



" Now, as he attacked every night the woodwork of his cage, 

 which I was gradually lining with tin, I bethought myself of 

 tj^ing some sticks over the woodwork, so that he might gnaw 

 these instead. I had previously put in some large branches for 

 him to climb upon ; but the others were straight sticks to cover 

 over the woodwork of his cage, which alone he attacked. It so 

 happened that the thick sticks I now put into his cage were 

 bored in all directions by a large and destructive grub, called 

 here the Moutouk. Just at sunset the Aye-aye crept from 

 under his blanket, yawned, stretched, and betook himself to 

 his tree, where his movements are lively and graceful, though 

 by no means so quick as those of a Squirrel. Presently he came 

 to one of the worm-eaten branches, which he began to examine 

 most attentively ; and bending forward his ears, and applying 

 his nose close to the bark, he rapidly tapped the surface with 

 the curious second [third] digit, as a Woodpecker taps a tree, 

 though with much less noise, from time to time inserting the 

 end of the slender finger into the worm-holes as a surgeon would 

 a probe. At length he came to a part of the branch which 

 evidently gave out an interesting sound, for he began to tear it 

 with his strong teeth. He rapidly stripped off the bark, cut 

 into the wood, and exposed the nest of a grub, which he 

 daintily picked out of its bed with the slender tapping finger, 

 and conveyed the luscious morsel to his mouth. 



*' I watched these proceedings with intense interest, and was 

 much struck with the marvellous adaptation of the creature to 

 its habits, shown by his acute hearing, which enables him aptly 

 to distinguish the different tones emitted from the wood by 

 his gentle tapping; his evidently acute sense of smell, aiding 

 him in his search." 



I have quoted thus at length these interesting observations 

 upon the grub-eating habits of the Aye Aye, for the reason 

 that there can be no doubt, apparently, that they are directly 

 responsible for the rodent-like character of the incisors, as well 

 as for the tendency to degeneration and reduction of the 

 molars and the curious modification of the third finger of the 

 hand which is made to fulfil the functions of a })robe, plex- 

 imeter, and scoop. We shall presently see in what way these 

 modifications throw light upon some of the extinct American 

 forms of this same group. 



The chief diagnostic features of the suborder have already 

 been given, and to these should be added the lack of bony 



