CH. l] AREA INHABITED BY CHIMPANZEE. 13 



tending itself by actual or passive migration right and left 

 and in every possible direction from this focus. Gradually 

 the form will be modified, or by competition or for some 

 other reason become extinct, leaving perhaps descendants 

 scattered here and there to tell the tale of a formerly wide 

 range. A guess can be made as to the comparative age of 

 a species or a genus by comparing such facts. 



In all probability these instances of a restricted distri- 

 bution are to be explained in one of two ways ; either the 

 form is a new one or it is an ancient one. A new species 

 recently come into existence would naturally, at least on 

 any theory of evolution, have a limited range because it 

 would have come into being at one locality and not have 

 had time to extend its range, supposing an extension to 

 be possible and not barred by impassable barriers. 



The former alternative applies probably to most of the 

 examples that have been used, particularly perhaps to the 

 peculiar species often found upon oceanic islands. There 

 are however numerous species, as limited in their range, 

 which are in some cases certainly vestiges of races once 

 universally or widely distributed. 



The Chimpanzee tribe is at present limited to the 

 forest region of central Africa. Its utmost range is nearly 

 across that continent. But the palseontological records of 

 India contain a description and figures of a portion of a 

 skull evidently belonging to a chimpanzee which at one 

 time existed in India. Probably that indicated the high- 

 water mark of the extension of the chimpanzee, which has 

 since retired to more restricted boundaries. We know 

 from historical records that the lion used to occur in 



