284 Natueal History 



spiny plants. Even this, however, is not satisfactory, for the 

 female, Avho must seek her food in the same way does not 

 possess them. I should be inclined to beUeve rather that 

 these tusks were once useful, and were then worn down as 

 fast as they grew ; but that changed conditions of life have 

 rendered them unnecessary, and they now develop into a mon- 

 strous form, just as the incisors of the beaver or rabbit will 

 go on growing, if the opposite teeth do not wear them away. 

 In old animals they reach an enormous size, and are generally 

 broken off as if by fighting. 



Here again we have a resemblance to the wart-hogs of Af- 

 rica, whose upper canines grow outward and curve up so as 

 to form a transition from the usual mode of growth to that 

 of the Babirtisa. In other respects there seems no aifinity be- 

 tween these animals, and the Babir^sa stands completely iso- 

 lated, having no resemblance to the pigs of any other part of 

 the world. It is found all over Celebes and in the Sula Isl- 

 ands, and also in Bouru, the only spot beyond the Celebes 

 group to which it extends ; and which island also shows some 

 affinity to the Sula Islands in its birds, indicating, perhaps, a 

 closer connection between them at some former period than 

 now exists. 



The other terrestrial mammals of Celebes are, five species 

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

 Borneo, and mark the furthest eastward range of the genus 

 in the tropics ; and two of Eastern opossums (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 Mammaha of Celebes are no less indi- 

 vidual and remarkable than the birds, since three of the largest 

 and most interesting species have no near allies in surround- 

 ing 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 colors 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 an- 

 imals would be still more prominent in these creatures with , 

 less stable organisms. On the other hand, however, we have 



