Ferns oF DutcHess County, NEw York 3 
3. PTERIDIUM AQUILINUM (L.) Kuhn. Abundant on 
hillsides and in open mountain meadows. 
4, ASPLENIUM TRICHOMANES L. This was found in 
but one or two localities and only a few small plants 
were found each time, growing on moist cliffs in the woods. 
5. ASPLENIUM PLATYNEURON (L.) Oakes. The ebony 
spleenwort, frequently so abundant, is apparently far 
from common here, being seen in only a few places. It 
was noticed in one locality upon a stone wall along a lane. 
Thriving individuals were also observed on the rocks 
lining an old well. 
6. ATHYRIUM THELYPTEROIDES (Michx.) Desv. Very 
abundant in rich woods, and one of the most common 
ferns of the region. 
7. ATHYRIUM Finrx-remMina (L.) Roth. Not very 
common, apparently, but some atypical, much reduced 
plants were collected. 
8. CAMPTOSORUS RHIZOPHYLLUS (L.) Link. The walk- 
ing leaf is as local here as elsewhere. A fine colony was 
observed on some boulders lying among hemlocks on an 
eastward slope. A few plants were found in another 
locality on a small mossy boulder lying in a brook. 
9. PotysticHuM AcROSTICHOIDES (Michx.) Schott. 
The common form of the Christmas fern is abundant. 
The writer collected plants, however, which afford an 
excellent example of entropic homoeosis, as defined by 
Mr. R. G. Leavitt.!. In these plants the pinnae have 
all been variously modified. In some of the fronds they 
are merely deeply toothed; in others they are pinnately 
cleft nearly to the midvein, and in some the two basal 
auricles have developed into pinnules, while the rest 
of the pinna is toothed. In a few fronds the sterile 
basal pinnae are truly pinnate, reproducing exactly 
the form of a normal frond. Even more striking are 
1R. G. Leavitt. A vegetation mutant, and the principle of homoeosis in 
Plants. Bot. Gaz. 47: 30-68. 1909. 
