184 MOSTLY MAMMALS 
the members of that group. Still, the whole character 
of the dentition is so essentially rodent-like that there is 
little wonder the old naturalists regarded the aye-aye as 
a near relative of the squirrels. 
The general anatomy of the aye-aye, especially the 
structure of its skull, shows, however, that it is certainly 
a near relative of the lemurs, which are themselves distant 
cousins of the monkeys, from which, among many other 
peculiarities, they differ by their expressionless, fox-like 
faces. The aye-aye is therefore classed as a lemuroid ; of 
which group, owing to the peculiarity of its dentition and 
its attenuated middle finger, it must be regarded as a highly 
aberrant and specialised member. 
Unfortunately, in spite of recent explorations in the 
superficial deposits of Madagascar, where bones of huge 
extinct lemuroids have been disinterred, nothing whatever 
is known as to the ancestry of the aye-aye. Evidently, 
however, it must be a comparatively ancient type, for, if 
we may judge from the analogy of other groups, a long 
period of time must have been required to allow of the 
gradual evolution and development of its characteristic 
peculiarities of dental and manual structure. 
Evidently these peculiarities must be connected with its 
mode of life. And we learn from those who have observed 
the creature in its native forests or in captivity, that the 
aye-aye, unlike the true lemurs, subsists largely upon wood- 
boring insect larvae, especially on the larva of a beetle known 
to the Malagasy by the name of andraitra. Apparently the 
aye-aye possesses a sense of hearing so acute that when 
on a bough it can hear the faint rasping sound made by 
the jaws of the andraita as it bores its way through the 
wood in the interior. Thereupon it at once sets to work 
with its powerful front teeth to chisel away the intervening 
