460 J. LeConte — Flora of Coast Islands of California. 



Readers of Mr. Wallace's "Island Life" will at once see the 

 analogy between this explanation of the flora of our coast islands 

 and Mr.Wallace's explanation of the mammalian fauna of Mada- 

 gascar. The mammalian fauna of Africa, south of Sahara, 

 consists of two very distinct groups — -the one indigenous or de- 

 scendants of Tertiary indigenes, and remotely resembling that of 

 Madagascar, the other evidently foreign and resembling that of 

 Eurasia in Miocene and Pliocene times. During Tertiary times 

 Africa was isolated from Eurasia, but united with Madagascar, 

 and the whole -inhabited by a peculiar fauna, characterized by 

 lemurs, insectivores, etc., which we have called indigenes. 

 About middle Tertiary times, Madagascar was separated, and 

 immediately divergence between the two faunas commenced. 

 In the later Tertiary and early Quaternary, the barrier which 

 separated Africa from Eurasia was removed, and the great 

 Eurasian animals invaded Africa, and immediately became the 

 dominant type. In the struggle which ensued, many species, 

 especially of the weaker indigenes, were destroyed, and all on 

 both sides modified. The result is the African fauna of to-day. 

 Madagascar was saved from this invasion by isolation. The 

 fauna there consists of the greatly modified descendants of the 

 African Tertiary indigenes, lout far less modified than their con- 

 geners in Africa. In the fauna of Madagascar, therefore, we 

 have the nearest approach to the Tertiary indigenes of both. 



The difference between the two cases is this : In the case of 

 Madagascar the separation has been very long. The extreme 

 peculiarity of its fauna is the result partly of progressive diver- 

 gence and partly of many forms saved by isolation. In the case 

 of the coast islands of California, the separation is compara- 

 tively recent — there has not been time enough for very great 

 divergence by modification. The peculiar^ of its flora is due 

 almost wholly to species saved by isolation. 



In conclusion I would say, that this short paper is intended 

 merely as an incentive to future investigation and pointing in 

 the direction which it ought to take. Before the views above 

 presented can be definitely established, there must be further 

 investigations, first, on the relation of the island flora to that 

 of the mainland ; second, on the relation of the flora of Cali- 

 fornia to that of adjacent parts from which it may have been 

 originally colonized ; third, and especially, must we have fuller 

 knowledge of the indigenous flora of California in Pliocene 

 times. 



