16 IN LOWER FLORIDA WILDS 



more than 140 species of tropical plants common 

 to this mainland and the Lower Keys which do not 

 occur on the Upper Keys at all! I can conceive of 

 no better evidence that the Miami coast and the 

 Lower Keys (which are likely of the same geo- 

 logical formation), though they were perhaps never 

 actually connected, were above the sea and were 

 receiving life drifted from the American tropics 

 a long time before the Upper Keys had become 

 dry land. If I am correct the Lower Keys should 

 be far richer in tropical life than the upper ones. 

 This is in fact the case for 440 such species of plants 

 have been reported from the former area as against 

 265 from the latter. Yet there is but little dif- 

 ference in the extent and surface features of the 

 two groups of islands. It is doubtful that they 

 have ever been connected by dry land. The 

 Moser Channel lying west of Knight's Key (of 

 the upper chain) and eastward of the lower chain 

 carries through a full nine feet of water from the 

 Gulf of Mexico to the Florida Strait, and this 

 channel has probably separated the two groups 

 of islands or keys from the time when the present 

 tropical flora and fauna first began to arrive. 

 The distribution of the animals of Lower 



