42 KEY TO THE GENERA AND SPECIES OF BRITISH MOSSES. 
170 Leave arcuato-incurved when dry ......c..sssesscsseeeees Trichostomum 
Leaves more or less crisped when dry Barbula 
N. excurrent in a mucro; one opaque.. SR i og Weissia, &e. 
171} Ls. variate ose, n. usu. vanishing ; cells dotte i oe arma Zygodon 
Ls. spreading; n. vane. pl. in dense cushio 172 
172 vo compat bright green me 1S. 2. GAGE fission, aegeiearene 
So and narrow, usu. dulle paler green 73 
173 Ls. te, te, linear- Cys cells m shocks opaque 174 
poake mg lanc.; subacute, or acute w. pellucid cells ...Gymnostomum 
174! Ls. curled up, or merely flexuose when dry ............ Amphoridium 
(Ls. erisped and twisted when dry Didymodon 
[Pievrocarrous Mossss, wir CLADOCARPOUS.] 
175 { Ls: searenieys oormplansts fe 176 
(Ls. planate 182 
176! U* ater or two. nerved 177 
(Ls. singly nerve 180 
177! (Ls. aS ME sie nerved more than half-way............s:se0 Hookeria 
(Ls. not bordered; nerveless, or vy. shortly two-nerved ...........0+0+ 178 
178 (Ls. v. obtuse, SUDERO ERENT 5. sells Ve LBS. sii pipsecrciens ...Pterygophyllum 
(Ls. or succulent: cells a 
179 (Branches pin le ls, usu. gar 
: | Brs. not pinnate; ls. flat (exc. P. undulatum).......4. {Pisin 
80 (Ls. distichous, with sheathing lamina at base Fisside 
‘ | Ls. not distichous, without shi eathing lamina 181 
(Ls. obtuse, or v. shortly apiculat Homalia 
= (Ls. acute or subacute (usu. net oe only) 214 
182 (Ls. strongly and uniformly. party secund Hypnum 
(Ls. not faleato-secunc 183 
* 
(Stem clothed Sees or w. numerous (usu. branched) villi eure? 
183) st em not obvi usly villot 
casita at back, nerved; 8 mar. meelty ——— Ecibeideem 
{| Ls. v. 
184; (Ls. smooth; stem ir regular arly or searcely pi 
(St. usu. red; . or l. widely ov oe usu. ape RR 2 memes 
APE a: not red; ls. anally ovate-lanc., w. long acumen...... btychodium 
(Ls. w. white hyaline a Geevilois or 2-nerved) ......... Hedwigia 
186; (Ls. without hyaline point 187 
% 
(Ls. w. long, curved, spinulose papille at back ...... Pterigynandrum 
187; | Ls. smooth, or m. or 1. finely papiliose 188 
189 
al we 
* 
(Ls. ee or pt geieierd two-nerved 
(Ls. singly n 
189 | (Pl. robust, st. it ls, scarions, acumin.; cells linear... Hylocomium 
(Stem not red (exe. in No. 202, with obtuse ls.) 190 
188 - 
+ Including Rhyncostegium depressum ; see under Plagiothecium. 
