200 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
forma obliquum (Muhl.) Fernald. — (B. ohJiquum Man. ed. 7 and 
111. Fl. ed. 2; vid. Rhodora, 23: 151, 1921.) 
Fields, hillsides, pastures and open woods; frequent. 
B. ramosum (Roth) Asehers. — (B. neghctum 111. Fl. ed. 2.) 
Rich leaf mould, chiefly under deciduous trees, often associated 
with B. angusfiscrimcntum; frequent. 
B. simplex E. Hitchcock. — New Ashford, in pastures not far from 
brook (Andrews); Washington (C. S. Lewis); rich woods, Stock- 
bridge; Sheffield (Churchill). 
B. ternatum (Thunb.) Sw., var. intermedium D. C. Eaton. — 
(B. sihifoliuvi 111. Fl. ed. 2.) 
Pastures and open woods; frequent. 
B. virginianum (L.) Sw. Rattlesnake Fern. — Rich woods; 
common. A plant from Florida has the fertile segment divided into 
two full-sized divisions. 
var. intermedium Butters. — {B. virginianum Man. ed. 7 in part.) 
Dry, rocky upland woods. North Adams (Fernald and Long). 
Boirychhim virginianum, var. intermedium has lately been dis- 
tinguished from the type {md. Rhodora, 19: 207, 1917). 
Ripe sporangia straw-colored, opening but slightly in detiiscence, their walla 
composed of regular cells; pinnules of the sterile frond ovate to lance-ovate, 
their ultimate segments spatulate B. virginianum, var. intermedium. 
Ripe sporangia brown, opening rather widety in dehiscence, their walls 
composed, at least in part, of irregular cells with sinuous walls; pinnules of the 
sterile frond much dissected, lanceolate, deeply pinnatifid or nearly pinnate, 
and the ultimate segments oblong or cuneate or decurrent at the base, lanceo- 
late and scarcely or not at all spatulate B. virginianum. 
OPHIOGLOSSUM. Adder's Tongue. 
O. vulgatum L. Adder's Tongue. — Mucky pockets in low 
meadows; frequent. In thin soil on a limestone outcrop in Great 
Barrington. 
f 
MARSILEACEAE. 
MARSILSA. 
M. QUADRIFOLIA L. — A small colony in the inlet to Prospect Pond, 
Egremont. An interesting European aquatic often cultivated and 
probably introduced, perhaps accidentally, at the above station. 
