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largely taken upon faith. This faith, in some cases, it 

 seems to me, has been somewhat misplaced, and while 

 the subject is fresh in mind I purpose pointing out what 

 appear to be some incorrect conclusions. 



The points depended upon for determining species in 

 the genus Isoctcs are about as follows : lobing of the 

 trunk, number, color and length of the leaves, number 

 of bast-bundles, presence of stomata, width of the velum 

 or indusium. character of the sporangia, size and marking 

 of the spores and habitat. It may be well to take a look 

 at these items, separately. 



Habitat. — For purposes of classification the Isoctacea 

 are usually divided into the four sections Aquaticae, Sub- 

 Aquatica?. Amphibia? and Terrestres, which contain re- 

 spectively species of deep water, species of shallow water, 

 species often exposed to the air and species normally 

 exposed to the air. This is at best a most arbitrary 

 division since plants are unable to choose their location 

 and must often be found in habitats that are far from 

 representative. Take the case of /. echinospora Braunii. 

 In the glacial lakes of Northern Pennsylvania, this 

 species, so far as I have observed, invariably grows too 

 deep in the water to be exposed even in the driest seasons. 

 Dodge's " Ferns and Fern Allies of New England," 

 however, says that the plants grow on the muddy shores 

 of streams. Now is this plant an aquatic or amphibious 

 species ? Baker says aquatic ; so does Underwood ; Dodge 

 and Eaton say amphibious ; I say, " when Doctors dis- 

 agree, who shall decide?" Again, Underwood's "Our 

 Native Ferns," 6th edition, names five terrestrial species 

 in North America. Of these, not a single species grows 

 in dry ground. They are found in regions subjected to 

 alternate drouth and flood. During the rainy seasons 

 they spring up in the temporary pools, and when the 

 moisture vanishes the leaves decay and the plant goes 

 into a state of aestivation. Sometimes, as in the case 

 of /. Orcutti, there is not enough rain for two or three 

 years in succession to form even temporary pools. Then 

 the plants do not appear at all ! Can such be properly 



