MONKEYS. 43 



method of increase making ample provision for their use as gnawing 

 instruments. Like the front teeth of the Rodents, those of the Aye- 

 Aye are covered on their front surfaces with enamel, which being 

 harder than the hinder ivory of which the bulk of the tooth is com- 

 posed, provides for a sharp edge being continuously kept up on these 

 teeth. As in the Rodents also, no " eye-teeth" are found in the Aye- 

 Aye. The thumb is scarcely opposable to the other fingers, and it 

 has a claw-like nail. The middle is the longest finger, and appears 

 to be specially adapted for picking insect food from beneath the 

 bark of trees. The ears are prominent, and the tail is bushy ; the 

 Aye-Aye thus resembling a squirrel in appearance. In its entire 

 structure, we witness a series of modifications adapting it for a life 

 amongst trees, and for an insect-dietary. Its affinities relate it deci- 

 dedly to the Rodents or rat-tribe and separate it from the lemurs ; 

 and the mere existence of this curious form serves to show how 

 the work of modification may proceed apace when the surroundings 

 of an animal favour its departure from the type of its race. 



The second great subdivision of the monkey-order is known as 

 that of the Platyrhini, or " broad-nosed " monkeys, which, without 

 a single exception, inhabit the New World. In the dense forests of 

 South America these monkeys are thoroughly at home. They are 

 eminently fitted for an arboreal life, and their whole organisation 

 indicates that the modifications to which their race has been subjected 

 have been chiefly directed towards their adaptation for a habitation 

 among the trees. Included within the limits of the " broad-nosed " 

 tribe we find such monkeys as the well-known Marmosets, the Spider 

 Monkeys, the Howlers, and the little Capuchins, whose tricks and 

 gentle ways endear them to all lovers of animals. In many respects 

 the marmosets stand alone amongst the New World forms. Their 

 fur is thick and woolly ; they are typically " four-legged '"' as regards 

 their walking movements ; and their tail is long and not adapted for 

 grasping. No cheek-pouches exist, nor are any " callosities " developed. 

 The ears are very prominent and are covered with hairs, whilst the 

 nostrils, as in all American monkeys, are broad and possess a wide 

 " septum," or partition, from the presence of which conformation 

 their " Platyrhine " cognomen is derived. The marmosets possess 

 short front limbs when these members are compared with the hind 

 limbs ; but their thumbs are not " opposable " to the other digits, 

 and the essential character of a " hand " is therefore hardly repre- 

 sented in these animals. The thumb, in fact, cannot be separated from 

 the other fingers, and to the great-toe much the same remark applies. 

 The sole of the foot in the marmosets is disproportionately long ; 

 and the great-toe is small and provided with a flat nail, whilst the 

 nails of the other toes are curved. The marmosets, as has been 



