THE MARSH FERN TRIBE. 125 
to the place in which it grows; for while Thelypteris loves 
the sunny swamps and Noveboracense, dryish shades, the 
present species demands the moisture of the one and 
the shade of the other and is to be found in deep wet 
woodlands. 
The rootstock, as might be inferred, creeps near the 
surface of the soil and sends up bipinnatifid fronds which 
are like those of Zhelypteris in general appearance but 
like those of NMoveboracense in colour, texture and the 
graceful curve of the blades. In technical language they 
may be described as lanceolate, acuminate, pinnate with 
numerous sessile, lanceolate, long-pointed, pinnatifid 
pinnez and narrow obtuse segments. 
In the vicinity of New York, the fertile fronds appear 
FRUITING PINNA, 
in July. They are slightly taller and more erect than 
the sterile and bear the medium-sized sori in a double 
row on the pinnules. The indusia are thin and rather 
more conspicuous than those of its nearest relatives. 
Although the frond may be heavily fruited, the pinnules 
appear never to become revolute as in 7helypteris. 
When seen growing in masses this fern seems almost 
identical with Moveboracense but single fronds show a 
very decided difference. While the lower pinnz may be 
slightly smaller than those in the middle of the frond, 
they are never so greatly reduced as in Moveboracense. 
The stipes are also muchlonger. The marks by which it 
may be distinguished from 7helypteris are the flat fertile 
