14 AMERICAN FERN JOURNAL 
the mountains of eastern Pennsylvania, though growing, 
like the species, on limestone, and evidently to be classed 
as indifferent also. The var. americana (formerly known 
as dilatata)has been tested near Lake Willoughby, Ver- 
mont, and there appears to favor slightly acid soils. 
Two of the hybrids of species of Dryopteris have been 
studied as to soil acidity, the so called Boott’s fern, 
D. Boottii, in Vermont, Pennsylvania, and Maryland, 
and the well-marked hybrid between D. marginalis and 
D. cristata in Pennsylvania and New Jersey. The for- 
mer grows on everything from sphagnum hummocks 
to limestone ledges, and is evidently indifferent. The 
latter, however, has not been observed in soil of greater 
acidity than subacid, and may provisionally be classed 
as a circumneutral soil plant. 
In the article on rock ferns already referred to, it was 
remarked that further study would no doubt result in 
extending somewhat some of the ranges of reaction re- 
corded; and it seems of interest to record here one in- 
stance of this. The ebony spleenwort, Aspleniwm 
platyneuron, was classified as a ecaleareous soil plant 
rather tolerant of acidity, but stated not to have been 
observed in typically mediacid soils. It has since been 
found to grow with remarkable luxuriance in mediacid 
decaying wood in the Dismal Swamp, Virginia. A capi- 
tal X, if not a bold-face one, should accordingly be placed 
in the 300 column in the table on page 17 of that article. 
This species thus becomes the widest-ranging rock-fern 
thus far recognized, (though really a woods-fern at the 
most acid extreme). The class should be changed, to 
indifferent. 
From the foregoing discussion it will be seen that the 
ferns of woods and swamps are on the whole less parti- 
cular than the rock ferns as to their soil reactions; and 
in but a single case, Dryopteris Goldiana and its variety 
celsa, are closely related plants sharply contrasted in 
