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 amphithecium from thickened parts 

 ■ of the cell walls; teeth always transversely barred. 



Bryales. 



a. Peristome single, seldom wanting. 



Dicranaceae, Leucobryacese, 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. 

 Orthotrichacese, Mitteniaceae, 

 Drepanophyllacese, Schistostegaceae, 

 Calomniacea?, Rhizogoniacese, 

 Bartramiace^, Timmiaceae, 

 Catoscopiaceae, Aulacomniaceae, 

 Meeseaceae, Mniaceas, LeptostomaceEe, 

 BryacejE. 



(b). Teeth of the endostome, when present, 

 opposite those of the exostome, either free 

 or united with the outer set. 

 Funcriaceae, Disceliace^, Oedipodiacese, 

 Voitiacete, vSplachnaceae. 



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 dorsi ventral and zygomorphic. 



Polytrichales. 



a. Peristoine of 4-6 teeth; sporangium actinomor- 



phic. Georgiaceae. Georgia. 



b. Peristome with numerous teeth; sporangium 



actinomorphic or zygomorphic. 



(a). vSporangium strongly zygomorphic and 

 dorsiventral. Buxbaumiaccffi. 

 Buxbaumia, Webera, Dawsonia. 



(b). Sporangium actinomorphic, usually pris- 

 matic. Polytrichaceae. Catharina, 

 Atrichum, Polytrichum, etc. 



