THE MOONWORT AND ITS ALLIES. 63 



reaches only to the base of the fertile. The latter varies 

 in size from a short stalked division bearing one or two 

 sporangia to a spike two inches in length." Mr. Eaton 

 writes me that tenebrosum can always be distinguished 

 from its allies by the notch in the tip of the sterile portion 

 and by the spores which are nearly twice as large as 

 those of simplex. The plant's small size and variable 

 nature have caused it to be regarded as a variety of B. 

 simplex also. 



Tenebrosum grows on the borders of maple swamps. 

 Where the earth is deeply covered with leaves, many 

 specimens are never able to reach the light and air, but bear 

 fruit, nevertheless. Thus far it has been reported from 

 Vermont, New Hampshire, Massachusetts and New 

 York. It is likely to be found elsewhere within the 

 range of the other small Botrychiums. In some spots, 

 two hundred and fifty specimens have been collected in 

 an hour. Our illustration was made from specimens col- 

 lected by Mr. Eaton. 



The name of the genus is derived from a Greek word 

 meaning a bunch of grapes and was given to this family 

 in allusion to its clustered spore-cases. There are twenty- 

 five or more species, widely scattered on the globe. In 

 America, they are exceedingly variable and present some 

 puzzling questions to the student. " Judging from size 

 and external appearances alone," writes Prof. Under- 

 wood, " a regular gradation of forms might be arranged 

 from the most diminutive undivided fronds of B. simplex 

 to the largest of B. Virginianum. 



