CHANGES IN FAUNA AND FLORA OF CALIFORNIA.— 

 ON THE POWER OF ADAPTATION IN INSECTS. 



BY H. H. BEHR. 



The power of adaptation to new circumstances plays a 

 most prominent part m the changes that take place in the 

 fauna and flora of newly settled countries. 



It is chiefly the want of this power that causes the dis- 

 appearance of types which were characteristic to districts 

 before the harmony of organic life was disturbed by the 

 interference of man. 



To illustrate the disappearance of such characteristic 

 features, it is only necessary to mention two instances, 

 which all old inhabitants will confirm as soon as their 

 attention is directed to them. 



Up to the year 1856 a considerable part of the neighbor- 

 hood of San Francisco was covered by a chaparral con- 

 sisting almost exclusively of C eanothus thyrsijiorus. Part 

 of this formerly impenetrable thicket has been removed 

 by human agency, and to a great extent has been re- 

 planted by our California Citfressits niacrocai'fa, Piniis 

 insignis, Australian Acaciae and Eucalypti. The more 

 remote part of this thicket, where human interference was 

 not directly at work, still exists, but in another shape, the 

 Ceanothus being replaced by Silybum JMariannui , a thistle 

 with large blotched leaves, originally at home in Mediter- 

 ranean Europe. 



Another instance of similar nature is the striking change 

 that has taken place in our aquatic vegetation. Our 

 brooks and pools, as far as sewerage does not disable 

 them to support phanerogamic vegetation, at present are 

 covered by the luxuriant growth of an African weed, the 

 Cotula coi'onopifolia, the round, yellow heads of which 

 are now familiar to the most superficial observer. Old 

 inhabitants will recollect the beautifully varied carpet 



2d Ser., Vol. V. August 12, 1895. 



