CHAPTER XIX 



APPLICABILITY OF AGE AND AREA TO ANIMALS 



At an early period of my studies of Age and Area, when once 

 I had found how universally operative it was in the Vegetable 

 Kingdom, it seemed to me that in all probability it must also 

 apply to animals, though perhaps with less force on account of 

 their capacity for movement. Accordingly, I asked Professor 

 J. Stanley Gardiner, F.R.S., for help, which was given in the 

 most unstinted manner, and for which I take this opportunity 

 of expressing my most grateful thanks. By his advice I investi- 

 gatecl some groups of Land Mollusca — animals whose locomotive 

 capacity is somewhat limited — and I found that their distribu- 

 tion agreed fairly closely with what would be expected under the 

 hypothesis of Age and Area. One or two other groups that he 

 also recommended showed the same thing. The great difficulty 

 in applying Age and Area to animals rests upon the fact that 

 Professor Stanley Gardiner pointed out, that in very many 

 groups either the systematic grouping or the geographical dis- 

 tribution is but imperfectly known, and that there are com- 

 paratively few groups in which our knowledge of both is fairly 

 complete. And of coiu'sc in applying a new principle like Age 

 and Area to the Animal Kingdom one must be very sure of one's 

 facts, and not leave it possible for any one to say that a more 

 complete knowledge of the subject would yield quite different 

 results. 



At this stage I left the subject for a while, being much occupied 

 with the extension of its application to plants. At a later period 

 Professor Stanley Gardiner recommended me to apply for help 

 to Mr Edward Meyrick, F.R.S., the well-known investigator of 

 the Micro-Lepidoptera, who had at his command all the known 

 facts about the systematic grouping and geographical distribu- 

 tion of this group. Mr Meyrick was so kind as to furnish me with 

 the figures of the numbers of species that occurred upon New 

 Zealand and upon other islands, and the genera to which they 

 belonged, and from these I was able to determine that this group 

 also had closely followed Age and Area in its distribution; not 

 so closely, perhaps, as the plants, but with sufficient approxima- 

 tion for the fact to be unmistakable. 



