320 ANIMAL DEFENCES 



the action of heredity through a long series of ages. In very- 

 hot cHmates, too, the question of temperature has to be taken 

 into consideration. And even where we may suppose the habit 

 to be protective it can only be partially effectual, for many 

 predaceous animals are notoriously nocturnal, and some of them, 

 at any rate, have become so because their prey took to feeding 

 at night as a protective measure. We may feel sure that every 

 new life-preserving device that has been evolved among animals 

 which are preyed upon results in some counter-move among the 

 aggressors. 



Some few monkeys are nocturnal in habit, and among these 

 may be particularly mentioned the Owl -faced Night- Monkeys 

 (species of Nydipithecus), widely distributed in South America. 

 The time at which these small animals feed is indicated, as in 

 many other cases, by their large eyes, around which the hair 

 is arrang-ed in a radiating manner, the two features combined 

 giving a very owl-like appearance. The chief enemies of the 

 inhabitants of South American forests are climbine snakes and 

 carnivores, and probably the attacks of these are to some ex- 

 tent avoided by the practice of feeding at night. But it must 

 be borne in mind that these night-monkeys themselves feed upon 

 insects and birds, which are more easy to surprise in the dark, so 

 that in this case the nocturnal habit would appear to serve a 

 double purpose. 



Primitive groups of animals often include a number of noc- 

 turnal members, and this is well seen in the order of Lemurs, 

 many of the smaller kinds of which are endowed with laree 

 staring eyes. Examples are the Aye-aye (Chiromys) of Mada- 

 gascar, and the Pottos {Perodicticus and Arctocebus) and Galagos 

 (Otolicmts) of Continental Africa, together with the Loris {^Nyc- 

 ticebus) and Spectre-Tarsiers {Tarsiiis) of the East Indies. As, 

 however, most of these live largely or mainly upon insects and 

 small vertebrates, the night-feeding habit is probably useful in 

 two ways, as in the case of the owl-faced night-monkeys already 

 described. If, as has been asserted, the West African Galagos 

 subsist only upon fruit and gum, the nocturnal arrangement may 

 possibly be purely protective. 



Bats are perhaps the most thorough-going night-forms among 

 Mammals, but as the great majority prey at dusk upon insects 

 which fly at that time, the habit is probably in relation to this. 



