KEY TO THE HARPIDIOID HYPNA. 
13 
J. A. WHELDON. 
( Continued from ‘ The Naturalist ’ for Oct., 1921 , p. 346 ). 
(F) Warnstorfia Loeske. 
Stem without paraphyllia ; cortical layer not differentiated. Leaves 
normally serrate, alar cells enlarged forming more or less distinct auricles, 
or rarely the cells are uniform and auricles obsolete. Cells linear, more 
or less vermicular. Nerve single, rarely furcate above. Perichaetial 
leaves smooth. Capsule exannulate. Inflorescence dioicous or 
monoicous. 
1. Alar cells suddenly very distinct, hyaline, inflated, usually 
forming conspicuous auricles : plants dioicous, usually more or less 
rigid : leaf base often dentate (29). Alar cells only slightly enlarged, 
more obscure, shorter, and forming less distinct, scarcely inflated 
auricles : plant usually autoicous, soft and flaccid : leaf apex usually 
dentate and occasionally rhizinose (4). Alar cells obsolete as in 
Limprichtia : lower margin more or less serrate, and leaf -apex occasionally 
producing rhizoids (2). 
2. Tall and robust (10-20 cm.), brownish to yellowish -green, 
pinnate : leaves strongly falcate -flexuose throughout (habit of robust 
H. Sendtneri) : nerve single reaching above middle, 56 ju wide at base 
(W. fluitans var. scotica) . Short and weak (3-10 cm.), green, hardly 
pinnate : nerve short, single or double (3). 
3. Leaves lanceolate, distant, flexuose -spreading, nerved about 
half way (W . fluitans var. J eanbernati f. Holleri). Leaves oblong- 
lanceolate, lightly homotropous, shortly decurrent : nerve often furcate,, 
short, in rameal ones nearly obsolete (W . fluitans var. hemineuron). 
4. Usually green : leaves secund or erect below, falcate at apices 
basal cells hardly incrassate, of uniform texture, rarely coloured : nerve 
rather narrow, 45-65 fj, (5). Usually yellowish, to chestnut or purplish- 
brown, rarely green above only : basal cells incrassate, subquadrate, 
often yellow or orange : nerve rather stout, 60-120 [a (20). 
5. Simple or slightly branched, hardly pinnate : usually rather 
short (6). Pinnate, often regularly and densely: usually tall and 
robust (17). 
6. Leaves with a long or short fine subule (7) . Leaves with narrowly 
acuminate but hardly subulate points (19). 
7. Green (fawn coloured in age) : leaves flexuose below, subfalcate- 
secund above, strongly narrowed to base (8) . Green or olive-green above, 
fuscescent below, or rarely mingled green and vinous : leaves from a 
broader base, erect or patent, hardly falcate above, except in var. 
squalidum (10). 
8. Slender, lax, and elongate: leaves distant, narrow, very long (9) .. 
Densely tufted; shorter, less flaccid : leaves smaller, more closely 
imbricate, shortly subulate, their points falcate recurved (W. fluitans 
var. gracile f. abbreviata). 
9. Green, slender, slightly branched : leaves lightly curved, narrow,, 
longly acuminate, dentate above : nerve thin (W . fluitans var. gracile). 
Whitish -green, very soft, flaccid, texture delicate and translucent : 
leaves very distant, very narrow and elongate, with extremely long 
filiform twisted points : basal cells lax, angular -decurrent (W . fluitans 
var. gracile f. laxifolia ). 
10. Leaves oblong -lanceolate, rather suddenly narrowed into a 
short fine subule (1 1 ) . Leaves linear-lanceolate, very gradually narrowed 
into a long fine subule (12). 
1922 Jan. 1 
