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of the caves of this section, has its entrance from above. At the 

 bottom of a large "sink" is an opening of about twenty feet wide 

 by an hundred long, with perpendicular walls of rock which 

 drop thirty to seventy feet, beneath which lies a large chamber 

 200 by 400 feet and 200 feet deep. The great uniformity of tem- 

 perature (about 60 deg.) and moisture in this sunken glen, 

 make the conditions perfect and these cliffs are densely covered 

 with mosses and ferns, some of which attain a wonderful de- 

 velopment, and all are practically "evergreen." Here I have 

 found Aspidium acrostichoidcs, Asplenium ebeneum, A. ebeneum 

 incisum, A. parvulum, A. trichomanes, Camptosorus rhizophyllus, 

 Cystopteris bulbifcra, C. fragilis, Pellaea atropurpurea, and 

 Woodsia obtusa. In all cave openings Pellaea atropurpurea 

 and Camptosorus are apt to be found, and often one or several 

 of the others. Sometimes the Woodsia and Cystopteris bulbifcra 

 will be found far back in the dim light, but there is a temperature 

 line which fern life seems to be unable to cross, 49 degrees. 

 Woodsia and Cystopteris are commonly found together; Camp- 

 tosorus is cosmopolitan. 



A number of ferns are as truly evergreen here as the Christ- 

 mas fern. In cave entrances where moisture and temperature 

 vary little during the year, many ferns keep up a continuous 

 growth, and specimens from prothallia to mature frond may be 

 obtained at any time. But even under more ordinary conditions 

 a number of species can be found with like habits. Except in 

 the dryest, most exposed places Pellaea atropurpurea carries its 

 fronds over until the next year's growth is mature, and in moist, 

 protected places can often be found in all stages of growth at 

 any time. The ebony and little ebony spleenworts, and maiden- 

 hair spleenwort, are evergreen like the Christmas fern. 



The maidenhair, rattlesnake fern, bladder ferns, Onoclea, 

 oak fern, the bracken and woodsia, lose their foliage in winter, 

 and send up new fronds in spring. Otherwise our ferns seem 

 to take a short rest during the hot, dry mid-summer season, and 



