214 
The Ohio Naturalist. 
[Vol. XIV, No. 2 , 
II. Archegonia situated at the tip of the main stem or of 
ordinary branches; frond usually of erect habit. 
1. Peristome single or double or sometimes absent, 
developed in the amphitheeium from thickened parts 
of the cell walls; teeth always transversely barred. 
Bryales. 
a. Peristome single, seldom wanting. 
Dieranaceae, Leucobryaceas, Fissidentaceae, 
Calymperaceae, Pottiaceae, Grimmiaceae. 
b. Peristome double at least in its inception, 
rarely wanting, the endostome thin and 
membranous. 
(a.) Teeth of the endostome alternating with 
those of the exostome. 
Orthotrichaceae, Mitteniaceae, 
Drepanophy 11 aceae, Schistostegaceae, 
Calomniaceae, Rhizogoniaceae, 
Bartramiaceae, Timmiaceae, 
Catoscopiaceae, Aulacomniaceae, 
Meeseaceas, Mniaceae, Leptostomaceae, 
Bry aceae. 
(b). Teeth of the endostome, when present, 
opposite those of the exostome, either free 
or united with the outer set. 
Funeriaceae, Disceliaceae, Oedipodiaceae, 
Voitiaceae, Splachnaceae. 
2. Peristome single or double, developed from two tissue 
layers of the sporangium; teeth consisting of entire 
cells, not transversely barred, or if developed from 
thickened parts of cell walls then the sporangium 
decidedly dorsiventral and zygomorphic. 
Polytrichales. 
a. Peristome of 4-6 teeth; sporangium actinomor- 
phic. Georgi aceae. Georgia. 
b. Peristome with numerous teeth; sporangium 
actinomorphic or zygomorphic. 
(a) . Sporangium strongly zygomorphic and 
dorsiventral. Buxbaumiaceae. 
Buxbaumia, Webera, Dawsonia. 
(b) . Sporangium actinomorphic, usually pris¬ 
matic. Polytrichaceae. Catharina, 
Atrichum, Polytrichum, etc. 
