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1900] Andrews, — Ferns of a deep ravine 229 
FERNS OF A DEEP RAVINE IN THETFORD, VERMONT. 
A. LEROY ANDREWS. 
A LOCALITY in the township of Thetford, Vermont, furnishes 
within a limited space such a variety of ferns, including several 
which are found very rarely, if at all, in the vicinity, that I am per- 
suaded to attempt a brief description of it. 
A deep, narrow ravine or gully cut in the side of a high hill, be- 
comes in spring the bed of a small drainage brook, which later, how- 
ever, becomes dry. Steep, rocky walls, clothed in a growth of 
forest, close out effectually the rays of the sun, producing that inde- 
scribable effect of forest twilight which we associate with the growth 
of certain species of ferns. In every available place is collected a 
thick deposit of vegetable mould. Here the ferns revel in a lux- 
uriance that, in spite of a remarkably dry season, is hardly short of 
tropical. They fringe the overhanging rocks, adorn every fissure, 
grow in immense feathery clumps of graceful fronds at the bases of 
the cliffs and along the brook-bed — a garden of ferns such as one 
seldom sees. 
But the interest is not wholly on the side of the æsthetic, — the 
botanist also comes away well rewarded. A canister of specimens 
furnishes the means for an interesting comparison and study. 
The species with their distribution are as follows: From the rocky 
pastures above straggle down large beds of Dicksonia püsiuscula, in 
varying shades of light and dark green. The other species, uniformly 
distributed on the steep slopes, are Aspidium marginale, A. acrosti- 
choides, Pteris aquilina, Phegopteris Dryopteris, P. polypodioides, with 
occasional sterile fronds of Onoclea sensibilis. Upon the flat tops of 
rocks grow little colonies of Polypodium vulgare, while delicate 
bunches of Cystopteris fragilis (apparently the season's second 
growth) cluster beneath them, rarely showing fertile fronds. In the 
accumulation of damp mould along the brook-bed grow the species 
deserving especial mention. Mixed in charming contrast of form 
and tint are large clumps of Aspidium marginale, A. spinulosum, var. 
intermedium, A. Goldianum, A, aculeatum, var. Braunii, Adiantum 
pedatum, Asplenium thelypteroides, A. angustifolium, with specimens 
of Botrychium Virginianum, while the outlet of the ravine is marked 
by a thicket of tall fronds of Onoclea Struthiopteris. 
The three species, Aspidium Goldianum, A. aculeatum, var. 
