Order 1. =Weisiaceæ.= Peristome, with 16 teeth arranged in
one series, rarely wanting. Leaf with midrib. _Campylopus_,
_Dicranum_ (_D. scoparium_, common in forests), _Dicranella_,
_Cynodontium_.--_Weisia_, _Gymnostomum_ (no peristome),
_Systegium_.
Order 2. =Leucobryaceæ.= Peristome with 16 teeth. Leaves with
three or more layers of cells, of which the external ones are
air-conducting and perforated (as in the Sphagneæ), the middle
one containing chlorophyll. _Leucobryum._
Order 3. =Fissidentaceæ.= Peristome as in the preceding ones.
The leaves are arranged in two rows on the plagiotropic shoots;
in _Fissidens_ the midrib of the leaf bears wing-shaped
outgrowths. _Conomitrium, Fissidens._
Order 4. =Seligeriaceæ.= Peristome with 16 undivided teeth. Very
small Rock-mosses. _Seligeria.--Blindia._
Order 5. =Pottiaceæ.= Peristome with 16 teeth, which are
divided almost to the base, or with 32 teeth. Calyptra
hood-like.--_Barbula (B. muralis, B. ruralis), Trichostomum,
Leptotrichum.--Ceratodon purpureus.--Distichium.--Pottia._
Order 6. =Grimmiaceæ.= The leaf-cells are often papillose;
in the upper portion of the leaf, small, and of roundish
shape. The calyptra is most frequently hood-like or conical.
_Eucalypta._--_Orthotrichum_, often with short-stalked capsule,
is found on trees.--_Coscinodon._--_Hedwigia._--_Grimmia_,
_Racomitrium_.--_Cinclidotus._
Order 7. =Schistostegaceæ.= The stems are of two kinds (see
above); _Schistostega osmundacea_, in caves, has a bright
emerald protonema.
Order 8. =Splachnaceæ.= The capsule has a large, collar-like
neck (see above). _Splachnum_ (especially on manure).
Order 9. =Funariaceæ.= Capsule pear-shaped. _Funaria_ (_F.
hygrometrica_ has a very hygroscopic seta, becoming twisted
when dry, and straightening with moisture); _Physcomitrium_;
_Discelium_.
Order 10. =Bryaceæ.= The capsule is thicker towards
the apex; most frequently pendulous. _Philonotis_,
_Bartramia_.--_Aulacomnium._--_Paludella
Meesea._--_Mnium._--_Bryum_, _Webera_, _Leptobryum_.
Order 11. =Polytrichaceæ.= Single peristome, formed by 16,
32, or 64 teeth. Leaves with longitudinal lamellæ on upper
surface.--_Polytrichum_ has long, hairy calyptra. _Catharinea_
(_C. undulata_, in forests).
Order 12. =Georgiaceæ.= Peristome with 4 teeth (see above).
_Tetraphis_ (_T. pellucida_ has gemmæ).
Order 13. =Buxbaumiaceæ.= Capsule asymmetrical; double
peristome: the interior one conical, with 16 or 32 longitudinal
folds.--_Buxbaumia_ (_B. aphylla_); _Diphyscium_.