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Anomodon rostratus (Hedw.) Schimp.* 
Leskea obscura Hedw. 
Pylaisia Schimperi Card. (P. intricata Bryol. Eur.) 
2. Acer saccharum-Fagus grandifolia. Maple-Beech Forest. 
This forest occurs locally in the old pre-glacial valley floors at the present 
altitude of about one thousand feet above the sea, and it probably once pre- 
vailed in this habitat. It extends up the bases of the gentle slopes to meet the 
slightly intermingling White Oak forest of the hill-tops and upper slopes. Most 
of the Maple-Beech forest has been cleared away, the soil being generally fertile 
and fairly well drained. So far as determined this forest has practically the 
same mosses as occur in the forest of the shaded slopes, mentioned below under 
“5,” but not quite so well developed, probably because of less dense shade and 
less moisture. 
3. Tsuga canadensis Association. Hemlock Forest. 
This forest occupies the dark, damp, cool, rocky ravine or gorge where the 
stream is now actively deepening its channel, and usually is best developed in 
the Pittsburgh district in the upper third of the smaller “runs,” at an altitude 
of about 950-975 feet above sea-level. The flora of this habitat is rather limited, 
where best developed the Hemlock being the only tree, and the lower herbaceous 
plants being very few. The moss flora is fairly large, although it would undoubt- 
edly be considerably larger were the walls of the gorge of other than the usual 
crumbling clay shales and soft sandstones. 
A. On dripping rock faces of gorge or at falls. 
Dicranella heteromalla [Dill] Schimp. Not common in this habitat. 
Hymenostylium curvirostre [Ehrh.] Lindb. ( Gymnostomum curvirostre [ Ehrh.] 
Hedw.*) 
Philonotis Muhlenbergii (Schwaegr.) Brid.* 
B. Damp shaly cliff of gorge. 
Barbula ungUiculata [Huds.] Hedw. 
Grimmia apocarpa [L.] Hedw. 
Webera nutans [Schreb.] Hedw. ( Pohlia nutans Lindb.) 
C. Calcareous rock cliff in gorge; very limited in extent. 
Fissidens minutulus Sull. 
D. Narrow non-calcareous rock ledges in gorge. 
Brachythecium flagellar e (Hedw.) Jenn. 
E. Stones in bottom of ravines and gorge. 
Amblystegium Juratzkanum Schimp. 
Amblystegium varium (Hedw.) Lindb. 
Brachythecium flagellar e (Hedw.) Jenn. 
Fissidens exiguus Sull. 
Fissidens minutulus Sull. 
4. Quercus velutina—Q. coccinea Association. Black Oak— Scarlet Oak Forest. 
On the remnants of the flood-plains and terraces of the main streams of the 
Old Monongahela System the soil is a deep rather rich gravelly or sandy alluvium 
