88 PROFESSOR OWEN ON THE AYE-AYE. 



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 mandibles. How safe from bills of birds or jaws of beasts 

 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 number, size, shape, 

 implantation, 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 further retreat. Such labour, however, 

 would have been too much for the reproductive power of even its strong-built, wide- 

 based, deep-planted, pulp-retaining incisors: in most instances we may well conceive 

 such labour of complete exposure of the burrow to be disproportionate to the morsel 

 so obtained. Another part of the frame of the Aye-aye is, accordingly, modified in a 

 singular and, as it seems, anomalous way, to meet this exigency. We m_ay suppose 

 that the larva retracts its head so far from the opening gnawed into its burrow as to 

 be out of reach of the lips, teeth, or tongue of the Aye-aye. One finger, however, on 

 each hand of that animal has been ordained to grow in length, but not in thickness, 

 with the other digits : it remains slender as a probe, and is provided at the end with a 

 small pad and a hook-like claw. By the doubtless rapid insertion and delicate appli- 

 cation of this digit, the grub is felt, seized, and drawn out. But, for this delicate 

 manoeuvre the Aye-aye needs a free command of its upper or fore limbs ; and, to give 

 it that power, one of the digits of the hind foot is so modified and directed that it can 

 be applied, thumb-wise, to the other toes, and the foot is made a prehensile hand. 

 Hereby the body is steadied by the firm grasp of these hinder hands during all the 

 operations of the head, jaws, teeth, and fore paws, required for the discovery and 

 capture of the common and favourite food of the nocturnal animal. 



Thus we have not only obvious, direct, and perfect adaptations of particular 

 mechanical instruments to particular functions, — of feet to grasp, of teeth to erode, of 

 a digit to feel and to extract, — but we discern a correlation of these several modifica- 

 tions with each other, and with modifications of the nervous system and sense-organs — ■ 

 of eyes to catch the least glimmer of light, and of ears to detect the feeblest grating of 

 sound, — the whole determining a compound mechanism to the perfect performance of 

 a particular kind of work'. 



' The Superintendent of the Zoological Gardens communicated to the Zoological Section of the British 

 Association at Cambridge, October 3rd, the fact that the Aye-aye then living in the Zoological Gardens refused 

 the mealworms, weevils, and other insects which had been offered to it for food. A repudiator of the principle 



