CH. XV] ENDEMISM AND DISTRIBUTION: SPECIES 163 



endemic genera of the Sandwich Islands, and compare them with 

 the endemic species in the non-endemic genera, one gets : 



Table showing the numbers and proportions of species of endemic 

 and of non-endemic genera that occur on all the Hawaiian Islands, 

 or 071 four to six islands, etc. Thus on all islands there occur 3-1 per 

 cent, of the species of endemic, 9-5 per cent, of the endemic species 

 of non-endemic genera. 



Species of Endemic species of 



endemic genera non-endemic genera 



Thus the species of the endemic genera are dispersed on the 

 average some 25 per cent, less than those of the non-endemic 

 genera. This proves on examination to be a general rule, and is 

 a powerful argument against local adaptation. It shows with 

 equal clearness in New Zealand and in Ceylon (123. p. 324.). 



If one go on to Ranunculus in New Zealand, which has " wides " 

 as well as endemics, while Olearia (above) has not, one finds 1/1, 

 1/2, 5/3, 7/4, and 14/5, taking only five classes instead of ten. 

 If one take at random in Vol. iv of Hooker's Indian Flora a few 

 genera, one finds in Exacum one species with large, six with inter- 

 mediate, and nine with small areas. In Chrisiisonia, where there 

 is no single widely ranging species, there are 4 with moderate 

 areas, and 6 with small. In Ebermaiera 1 has a very large, 6 an 

 intermediate, and 21 a small area. Or, finally, take Cyrtandra 

 (above); there are, roughly, 2 with very large areas, about 20 

 with fairly large, and about 145 with small, these latter again 

 showing gradations down to the smallest, as we have just seen 

 (p. 160). 



It is clear that the distribution of endemics is only a sppoi.nl 

 case of a vdde general phenomenon — that there are, in any family 

 or genus of reasonable size, a few species of wide dispersal, and 

 others of less and less dispersal in increasing numbers, the in- 

 crease being more rapid as one descends the scale, so that the 

 curve produced is hollow. When, as in very many genera, there 



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