284 ANNUAL OP SCIENTIFIC DISCOVERY. 



THE AYE-AYE (Chiromys Madagascariensis). 



This curious animal, which has recently been brought anew to the 

 attention of naturalists, by a monograph by Prof. Owen, of England, 

 was first noticed jn Madagascar by Souverat, in 1 780, and owes its 

 name to an exclamation of astonishment uttered by the natives of the 

 east coast, to whom, it is said, he exhibited it for the first time. Sou- 

 verat brought home with him a stuffed skin and a cranium, which have 

 since remained in the museum of the Garden of Plants, the only rep- 

 resentatives of the species in European cabinets. Zoologists have been 

 puzzled as to the true affinities of the Aye- Aye,' some placing it among 

 the Rodents, and others among the Quadrumana. A specimen pre- 

 served in spirits, recently forwarded by Dr. Sandwith to Prof. Owen, 

 has, however, enabled him to determine definitely its position among 

 the Lemuridse. But remarkable as the mingling of Rodent and Quad- 

 rumanous characters may be in the Aye-Aye, they are surpassed in the 

 correlations of physical structure and strange habits. " The wide open- 

 ings of the eyelids, the large cornea and expansile iris, the subglobular 

 lens and tapetum, are arrangements for admittting to the retina and 

 absorbing the utmost amount of light which may pervade the forest, at 

 sunset, dawn, or moonlight. Thus the Aye- Aye is able to guide itself 

 among the branches in quest of its hidden food. To detect this, how- 

 ever, "another sense had need to be developed to great perfection. The 

 large ears are to catch and concentrate, and the large acoustic nerve 

 and its ministering ' flocculus ' 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 jnandibles." The 

 food of this nocturnal animal, to whose strange physiognomy the eyes 

 and ears add so much, consists mostly of wood-boring grubs. To ex- 

 tract these, there are, united with the common Lemurine characters, 

 chisel-shaped incisors, resembling those of Rodents, and a most remark- 

 able modification of the middle finger, which is not only used for elicit- 

 ing by percussion the hollow sound from the bored limb, but as a hook 

 for extracting the grub. All the fingers are of somewhat unusual 

 length, but the middle one " 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." The 

 use made of this part will be best learned from the very interesting 

 letter to Prof. Owen by Dr. Sandwith, in which his own observations 

 on the habits of the Aye- Aye are recorded. 



" In a cage where a fine male healthy adult Aye- Aye was confined, 

 were placed a large number of branches, bored in all directions, by a 

 large and destructive grub, called the Montouk. 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 atten- 

 tively ; and bending forward his ears and applying his nose close to 

 the bark, he rapidly tapped the surface with the curious second 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 



