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THE AMERICAN MUSEUM JOURNAL 



Gulf Stream. These are the Uj)per 

 Florida Keys (coral) and the Lower 

 Florida Keys (limestone). The Upper 

 Keys are for the most part long and 

 narroAv ridges of coral rock and are 

 clothed with hardwood forests which 

 harbor two species of ferns not yet 

 known to occur on the Everglade Keys. 

 The Lower Keys are more spread out, 

 and rather less elevated above the sea. 

 They are clothed both with hardwood 

 forests and, in the case of a half dozen 

 islands, with pine woods at least in 

 part. The Lower Keys have as yet dis- 

 closed no ferns not already known on 

 the Everglade Keys. In fact, the 

 Florida Keys have a much smaller fern 

 flora than the Everglade Keys. Only 

 about one fifth of the species of the 

 Everglade Keys have been found there. 

 No doubt in their past the fern flora 

 was larger than it is now. It may have 

 rivaled or excelled that of the Ever- 

 glade Keys, for the Florida Keys con- 

 sist of two areas of different ages, 

 coral and limestone; but this region 

 has been for a long time decidedly on 

 the wane. 



In addition to the leaching process of 

 erosion that has reduced the surface of 

 the Everglade Keys, the Florida Keys 

 have had the mechanical and chemical 



action of the sea to contend with, and 

 the evidences of reduction are not hard 

 to observe. Compared with the Florida 

 Keys the Everglade Keys have had a 

 very peaceful existence. The latter have 

 been sheltered by their inland position, 

 while the Florida Keys have received 

 the hard knocks. These islands not only 

 have been worn down and washed away 

 l)y the never ceasing action of the sea, 

 but also by the hurricanes of ages. This 

 is quite evident. The rock surface, par- 

 ticularly in the case of the Lower Keys 

 whose limestone corresponds to that of 

 the Everglade Keys, is polished off and 

 platelike, instead of merely leached out 

 and honeycombed. What the former 

 fern flora consisted of we cannot even 

 imagine, but we are safe in assuming 

 that it was more extensive than that 

 which we find there now. 



About two score years ago a writer on 

 ferns, judging from a few collections 

 that had reached him from southern 

 Florida, predicted that more tropical 

 American ferns would be discovered in 

 that region. Since the beginning of this 

 century his prophecy has been fulfilled 

 by the discovery of about a score and a 

 half of ferns and fern allies before 

 know^n only from insular and continen- 

 tal tropical America. 



This creeping wood fern is a "walking fern." The long tips rest on the surface of the rock, take 

 root, and form new plants, which in turn repeat the process. The fern is reproduced also by spores 

 which are borne in round spore cases on the lower surface of the leaves. This colony of walking fern 

 was found growing on the perpendicular walls of a lime sink in a high pineland hammock 



