CH. xiii] D. GEOGRAPHICAL DISTRIBUTION 159 



island was occupied, so far as a given genus was concerned, by 

 one or more widely ranging species, usually very variable, such for 

 example as Metrosideros j^olymorpha. Then the wide-ranger was 

 accompanied by one or more local endemics, allied to it, and 

 finallv there were onlv the endemics. He thousrht that the wide- 

 ranger had given rise to the endemics, and might, or even did, 

 ultimately disappear (swamped, cf. 66, p. 95) (cf. 74, pp. 611- 

 13). 



It is the general experience of systematists that it is only in 

 numerous and widely ranging forms that this variability occurs 

 (cf. p. 132 for axioms). Linnaeus (12th ed., ii, 324) gives a list of 

 thirty such polymorphous genera, including willow and saxifrage 

 in Europe, oak and Aster in North America, Cactus in South 

 America, heather and everlastings at the Cape. 



Another way to bring out this point is to look at the synonyms 

 in generic indices like the Index Kewensis. The first forty-five 

 generic synonyms at the beginning of C are referred to genera of 

 an average size of 94, the mean for all genera being 14-15. The 

 first seventy in de Dalla Torre's Indea; are merged in genera with 

 an average of 70, or in both cases definitely large genera. 



Let us begin with the Indian Anemones, which show 



A. rivularis All mountains of India and Ceylon 



rupicola Kashmir to Sikkim 



vitifolia Himalaya, Mishmi Hills 



Griffithii Sikkim, B ho tan, Mishmi 



Falconeri W. temperate Himalaya 



ohtusiloha Temp, and alpine, Kashmir to Sikkim 



rupestris Alpine, Kashmir to Sikkim 



trulUfolia Sikkim to Bhotan 



demissa Alpine, Sikkim 



polyanthes Kashmir to Sikkim 



tetrasepala Western Himalaya 



elongata Garhwal, Nepal, Khasias 



Or take Clematis, § Cheiropsis; C. montana is common all along 

 the Himalaya, while C. napaulensis, C. barbellafa and C. acut- 

 angula are confined to particular sections. These two genera are 

 simply the first that occur in the flora, and almost any Himalayan 

 genus will show the same thing, whilst it is also shown by the 

 genera of lower levels, e.g. Portulaca: 



P. oleracea All India and Ceylon, and all warm countries 



quadrifida All India and Ceylon, and palaeotropical 



WighUafia Carnatic to Ceylon. Endemic 



tuherosa Behar to Ceylon. Endemic 



siijfruticosa W. Peninsula, Ceylon. Endemic 



