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ance is not everything. The so-called B. ternatum dis- 

 section differs from B. ternatum obliquum only in a lack 

 of leaf substance between the ultimate veins. I have 

 recently described a form of Dicksonia pilosiuscula based 

 upon this very particular. No one would call it a species, 

 and I fail to see how the many recently described species 

 of Botrychium can be so considered, when all are based 

 simply on the mere minor cutting of the sterile part of 

 the leaf. It is especially hazardous to describe species 

 based upon such characters in the genus Botrychium, 

 which is noted for its great diversity of cutting. Prof. 

 Underwood has rightly written : " Judging from size 

 and external appearances alone, a regular gradation of 

 forms might be arranged from the most diminutive undi- 

 vided fronds of B. simplex to the largest of B. Virginia- 

 nu m." Equally groundless, it seems to me, are the rea- 

 sons for giving a new name to the Jamaican specimens of 

 Botrychium Virgiuianum, because they have two fronds. 

 Jenman long ago noted the two fronds, but did not con- 

 sider the two species distinct, although if the Jamaican 

 form habitually produced two fronds and was otherwise 

 like the species, it would be entitled to rank as a sub- 

 species. It turns out, however, as I have shown, that 

 the second " sterile frond " is merely that of the preced- 

 ing year, which the mild climate allows to live through 

 the winter, and which bears the scar left by the fertile 

 part. Remove the plant to New York, and it would 

 promptly produce but a single frond a year. The differ- 

 ence between these forms, then, is eighteen hundred 

 miles ! 



It may be seriously doubted whether a plant differing 

 in all of these minor characters from another form, but 

 resembling it in all the characters which I have noted as 

 essential, would be entitled to specific rank. On the 

 other hand, so well known are the essential characters 

 that if one form differed from another in but one of them 

 it would certainly be called a sub-species, and possibly 

 a species. No doubt the matter I have outlined may be 

 modified in some particulars, but I believe, until some 



