The Aye- Aye. 133 



hinder hand has a powerful grasping thumb, and resembles 

 closely that of the lemur, and other nocturnal quadrumanous 

 animals. 



The teeth of this animal, however, offer a remarkable depar- 

 ture from the monkey type. The fore teeth, as shown in the 

 views of the skull, are truly those of a rodent or gnawing animal, 

 having sharp, cutting edges, and are furnished with a layer of 

 enamel on the front surface, which, like the steel facing of an iron 

 chisel, keeps them constantly keen and in cutting order. Like 

 the teeth of a rodent, they are continually growing during 

 the life of the owner. They differ, however, somewhat from the 

 incisors of our common gnawing animals, in being very narrow 

 in proportion to their great depth from front to back. 



The grinding teeth are much more vertical in their position 

 than those of rodents, and instead of being formed of alternate 

 transverse vertical ridges of bone and enamel are capped with 

 smooth crowns of enamel, as in man and the quadrumana gener- 

 ally ; their number is unequal, being, as shown in our engrav- 

 ings, four in the upper, and three in the lower jaw. The skull 

 compared with that of the squirrel, is larger, the brain-case 

 being well developed, and the brain itself resembles that of a 

 lemur, and not that of a rodent. This wonderful combination 

 of the structure of two groups of animals, so widely removed as 

 are the quadrumana and the rodentia, has hitherto proved exceed- 

 ingly puzzling, especially to those naturalists who imagine that 

 all animals should be constituted with reference to some given 

 type. To those, however, who are intent upon tracing the 

 intimate relation that exists between structural peculiarities 

 and habits, the aye-aye is one of the most interesting of all 

 animals, but until the exact nature of its habits were made 

 known by the communication of Dr. Sandwith, this relation 

 could not be accurately traced. 



The aye-aye is a nocturnal animal, sleeping during the day 

 and becoming active at night, as might be inferred from its 

 large circular eyes, wide iris, and great expanse of pupil. Its 

 food, as indicated by its simple molars, consists in great part of 

 fruits and soft vegetable substances, such as dates ; that it is a 

 climber is evidenced by the grasping character of its ex- 

 tremities. It was not until Dr. Sandwith accidentally placed 

 some branches for the living animal to climb, that the true 

 co-relation of its organs to its habits was noticed. These 

 branches had been perforated by some wood-boring larvae. On 

 being placed in the cage of the aye-aye, the animal was observed 

 to direct the large expansive ears towards them; when its 

 acute sense of hearing gave evidence of the working of some 

 concealed insect in a larval state. The long attenuated finger, 

 that even Buffon himself could now no longer regard as a defor- 

 VOL. i. — NO, II. L 



