32 
Wisconsin Academy of Sciences , Arts and Letters. 
II. Dioicous, stems sub-radiculose above, costa flat , equalling or broader 
than the 2—4 -stratose lamina whose superficial cells are without 
chlorophyll, capsule erect, regular. 
Costa not furrowed at back, smooth . . . . D. albicans, 11. 
Costa furrowed and toothed at back . . . D. longifolium, 10. 
III. Dioicous, stems radiculose {often densely), costa with median guides. 
A. Capsule cernuous, more or less arcuate. 
1. Leaf cells pitted. 
a. Costa not reaching the apex, leaves transversely undulate. 
Leaf cells above elongated, smooth. 
Costa serrate on back, not lamellose. 
Capsules solitary (rarely 2), annulus 0 . . D. palustre, 19. 
Capsules clustered, annulus large, simple . D. Druminondii, 22. 
Costa with serrate lamellae. 
Capsules clustered, perichaetial leaves differentiated D. undulatum, 23. 
Capsules solitary (?), perichaetial leaves like others I). dipteroneuron. 1 
Leaf cells above isodiametric, irregular. 
Smooth at back. D. Schraderi, 20. 
Papillose at back. D. spurium, 21. 
b. Costa per current or excurrent , leaves not undulate. 
[D. palustre may be sought here.] 
Guides in two rows .D. niajus, 18. 
Guides in one row. 
Perichaetial leaves abruptly subulate . . . D. scoparium, 17. 
Perichaetial leaves gradually subulate . . . .3). Howellii. 2 
2. Leaf cells not pitted or faintly so. 
a. Capsules cernuous, curved. 
i. Leaves quite entire, subulate. 
Points very brittle and mostly broken . . . 1). fragilifolium, 16. 
Points not broken ........ B. elongatum, 12. 
ii. Leaves entire, upper obtuse . D. Groenlandicum, Brid. 3 
Lower cells rectangular (1:2-3) .... D. Miquelonense. 4 
1 Muller: Flora, 1887. 221. 
2 Renauld & Cardot: Bot. Gaz. xiv (1889) 93, pi. XII. 
3 S.yn. D. tenuinerve, Zett.—Renauld & Cardot: FI. Miq. 42 (1888); Bot. Gaz. xiv. 
<1889) 99. 
* Renauld & Cardot: FI. Miq. 42 (1888); Bot. Gaz. xiv. (1889) 93, pi. XII. 
