436 NATURAL HISTORY [chap, xviii. 



of squirrels, which are all distinct from those of Java and 

 Borneo, and mark the furthest eastward range of the genus 

 in the tropics; and two of Eastern opossnms (Cuscus), 

 which are different from those of the Moluccas, and mark 

 the furthest westward extension of this genus and of the 

 Marsupial order. Thus we see that the Mammalia of 

 Celebes are no less individual and remarkable than the 

 birds, since three of the largest and most interesting 

 species have no near allies in surrounding countries, 

 but seem vaguely to indicate a relation to the African 

 continent. 



Many groups of insects appear to be especially subject 

 to local influences, their forms and colours changing with 

 each change of conditions, or even with a change of locality 

 where the conditions seem almost identical. We should 

 therefore anticipate that the individuality manifested in 

 the higher animals would be still more prominent in these 

 creatures with less stable organisms. On the other hand, 

 however, we have to consider that the dispersion and 

 migration of insects is much more easdy effected than 

 that of mammals or even of birds. They are much more 

 likely to be carried away by violent winds ; their eggs 

 may be carried on leaves either by storms of wind or by 

 floating trees, and their larvae and pupae, often buried in 

 trunks of trees or enclosed in waterproof cocoons, may be 

 floated for days or weeks uninjured over the ocean. These 



