Key to North American Sohagna 
 
ZL Chlororhyl-c11s of the branch 
le~aves ,suall, exposed - Jlittle 
iore broadly on the inner surface. 
/V Pores on the outer surface of the 
branch-leaves if :Jrcsent, never 
more than 2 per cell.     26. S. Pylaesii. 
/Y/'VPor" s on the outer surface 
of the branch-or stem-leaves 
always more than 2 
per cell.                 27. S. cyclophylum. 
A<'Hyalin(- cells of the branch-leaves 
without fibrils.                 28. S. macrophyllum. 
£AzChlrophyl-cells of the br-nch-leaves exp-se2d 
exclusively or more broadly on the inner surface; 
or, if with centr-l Iumon and qoproximately equal 
exposure, the pir cnt red. 
fStem-lcevcs ficTbriate-laccrate in the anical nart. 
Lacerate bctii at sides and anox.            29. -. fimbriatum. 
Laceratc. only acr  sc the broad truncate apex 30. S. Gircnsohnii. 
,p.Stcm-lavcs not notibl' lacerate in the apical 
part. 
Outer walls of the cortical cells of the stem 
ncres , mostly 1 ncr   er cll.              31. S. robustum. 
Outer wills of 1.r c'r-.ral c        1 rf th  stem 
not norn-'Ily rcs e. 
A1 Hyaline c, 1 s r'f L br'inch-l-nv s smaller, 
their fr   cTrv;wxi ty (n1 the ctcr svrPcc 
mostly less tht  on  -If their dia:cter. 
- Pignnt br,,r*r.                        32. S. fuscium. 
Z Piprient red. 
J Branch-iecvcs r~irlu"lly invclute-pointed 
to the apex. 
,e Outer surf- ccf thc branch-leaves with 
very srmall round strongly ringed pores 
in the anical nlrt,             33. S. Varnstorfi. 
"Outer surface (f thc branch-leaves with 
much lerger elliptic pores. 
L Stem.-luavcs largc, linsulate to lingu- 
latc-ovtc, cn,, and one-half or more 
tire s as long :s wide.      3h. S. capillaceun. 
LL Stc;u-ley v.vs small r, triangular 
'cO lingulate-tri. ngular, mostly 
a s wiC as long.            35. S. quniqucfarium. ' 
%T.Branch-Luaves abruptly involute-pointed tc 
thc 'pvx.                          36. S. meridense. 
///Hyaline cells cf th- branch-leaves larf!e in section, 
their froe c, nvoxity on the outer surfacc 
usually m, re Lhn cne h-if their dirneter. 
z Pigment brewnscmctin.cs )assinv t( 
purplish.                      37. S. olumulosum. 
2Z Pigm'nnt red. 
7 IMargin of th- branch-l aws .ntirr. 32   . t-ncrun. 
tA i.argin of th: branch-!eavcs 
d ntic'l1-..                39. S. tabulare, 
 
p. 15