1890.] Certain Peculiarities in the Flora. ae 
It may, on the other hand, happen, when islands preserve uni- 
formly the past conditions of the mainland for a longer time than 
the continents, that their fauna and flora resemble an older 
assemblage of life of the land of which they are a part, and with 
which they were formerly connected. 
It is believed that the Santa Barbara islands illustrate this latter 
statement. Climatic changes have, it is thought, taken place on 
the mainland which have changed the enviroment’ to that extent 
that animals and plants once found there have succumbed and 
disappeared, while these conditions have remained more constant 
on the islands, where, as a consequence, the destruction of certain 
organisms has not been so rapid. 
It may be borne in mind, however, that the causes which have 
led to the restriction of certain plants or animals to circumscribed 
localities in other parts of the world are not all understood. This 
restriction or local distribution may be due to general or to local 
causes, yet the former may at times be called to aid when the 
latter are insufficient. In New England, for instance, a local 
distribution of certain plants in limited areas often occurs and no 
explanation can be discovered for their limitation. It must, there- 
fore, be with diffidence that one finding peculiarities in the flora 
of certain islands ascribes those characteristics to far-reaching 
rather than local influences. Especially must one use caution in 
the study of phenomena in which more facts are necessary. The 
following paper, however, uses the data given by others, but with 
this precaution, knowing that such speculations may be over- 
turned by new observations and more extended studies bearing 
on the pecularities of the flora of the islands. 
Of the later geologic phenomena which have been called in 
to account for the present distribution of animals and plants, the 
glacial period is one of the most important. Possibly too great 
influence has been ascribed to it on account of the nearness of 
this period to the present, which it might be expected to most 
1 In environment are included organic as well as climatic changes. The o) 
vironment makes itself felt in a struggle for existence, which counts for as much as, if not 
more climatic chang: 
