138 PROFESSOR OWEN ch. v. 



utmost amount of light which may pervade the 

 forests at sunset, dawn, or moonlight. Thus the 

 aye-aye is able to guide itself among the branches 

 in quest of its hidden food. To discern this, 

 however, another sense had need to be developed 

 to great perfection. The large ears are directed 

 to catch and concentrate, and the large acoustic 

 nerve and other structures of the organ seem 

 designed to appreciate any feeble vibration that 

 might reach the tympanum from the recess in the 

 hard timber, through which the wood-boring larva 

 may be tunnelling its way, by repeated scoopings 

 and scrapings of its hard mandible. How safe 

 might seem such a grub in its teak or ebony-cased 

 burrow ! Here, however, is a quadrumanous 

 quadruped in which the front teeth, by their great 

 size, strong shape, chisel structure, deep implanta- 

 tion and provision for perpetual renovation of 

 substance, are especially fitted to enable their 

 possessor to gnaw down with gouge-like scoops to 

 the very spot where the ear indicates the grub to 

 be at work. The instincts of the insect, however, 

 warn it to withdraw from the part of the burrow 

 that may be thus exposed. Had the aye-aye 

 possessed no other instrument — were no other 

 part of its frame specially modified to meet this 

 exigency — it must have proceeded to apply the 

 incisive scoops in order to lay bare the whole of 

 the larval tunnel, to the extent at least which 

 would leave no further room for the retracted grub's 



