Eaton : Pteridophytes observed in Florida 457 



day each at Fort Myers and Fort Ogden and then returned to 

 North Easton. 



Physical and botanical features of the region 



Miami is very near the northern limit of the coral formation 

 which lies along the southeast coast of Florida from the vicinity 

 of Miami about 50 miles southward. Northward from Fort 

 Lauderdale the surface is overlaid by fine white silicious sand, 

 with its characteristic vegetation. Between this place and Miami 

 lies the borderland, where the southern calcareous rocks, of cor- 

 aline origin, dip down gradually under the sand, and where, there- 

 fore, the latter lies here and there in patches and in pockets of the 

 lime substratum. 



Below Miami, we pass into a new world of plants. The lime- 

 stone is usually bare of soil, save for a very small amount of 

 humus lodged in the interstices, is irregularly eroded and leached 

 away in the most fantastic shapes, and is for the most part exceed- 

 ingly rough and full of hollows and sharp cutting points. This 

 coastal lime formation is from 2 to 6 miles wide and is covered 

 with a growth of Pinus Elliottiana to the practical exclusion of 

 other trees. Ferns are very scarce on the higher elevations, but 

 on the borders of the so-called "prairies " — incursions of the ever- 

 glade — and hammocks, where there is more dampness, there is 

 usually an abundance of Aneimia adiantifolia and Ptcris longifolia. 

 Along the sea front there is likely to be a mangrove swamp, in- 

 habited by two species of Acrostichum. The Everglade proper is 

 an open shallow lake in summer, the water receding and leaving 

 large areas of damp marsh in winter. I found no fernwort in the 



open everglade. 



All angiospermous woods are called hammocks by the Flor- 

 idians ; and hammocks may be classed as of two kinds, those of 

 the everglades and river-borders and those of the pine woods. 

 The first are simply low, occasionally inundated islands in the 

 everglades or in the swamps bordering the rivers. The under- 

 growth is a tangle of small trees and shrubbery. I found no new 

 epiphytic ferns here, but these hammocks are the home of several 

 terrestrial species, some of them new. The pine-land hammocks 

 are simply isolated pieces of angiospermous woods in the pine 



