HYPNODENDRACEAE. 343 
If the arcuate seta which occasionally occurs were constant in 
certain plants, it would probably _be correct to make it a variety, 
as is held by several authors. Comparison of a large number 
specimens, however, shows that the curving of the seta is a very 
slight and inconstant character; both straight and more or less 
eurved setae are often found on the same plar it — occasionally a 
Consequently Hedwig’s name must be retained for the species. 
2. Hypnodendron marginatum (H. f. & W.) Jaeg. Adumbr. ii, 624. 
Syn. Hypnum marginatum H. f. & W. in Lond. Journ. Bot. 
iii, sue (1844). Isothecium marginatum H. f. & W., 
FI. ii, 106 (1855 M4 Han ess ae Hl, pe 466. 
Ay fv limbatum Sull. m Pro r. Acad. iii, 183 
(1854). Scraromium eR are ei Aanee ii, "556. 
A taller, more distinetly peat plant bese 4 in ay Rhee 
forms) than the previous spec the stipes chin 
the frond, which is more distinctly iinBellats: with ie. Dare ee 
and often drooping branches, up to 7 em. across. The colour of 
nal i eral rows much longer, Lame incrassate, forming a very 
distinet, prin ed | arcs The is ve thes similar, but the setae 
are very numerous on a single — Nod er. 
The aquatic forms which entnie: occur are very remarkable 
in habit, being non-dendroid, soft and flaccid, sometimes with the 
in herbaria as F , and ras. Structurally, however, 
they agree quite well with the typical plant, usually d only 
in the less strongly toothed margin ery he characteristic 
areolation is constant. Hypnum limbatum Sull. is one of these forms, 
differing however from most in having ths leaves decidedly narrower, 
lanceolate and more acute; it was gathered on stones at the bottom 
of streams. 
Sciaromium Bellii differs from these forms in the much less 
marked border, almost entire leaves, and longer and narrower 
interior cells. 
Mnriopenpron Lindb. e Broth. in Engl. & Prantl, Pflanzenfam., 
. Muscei, ii, 1170 (1909). (Hypnum, les Hyp eget ay 
Subsect. Comatulina C.M., Syn. ii, 503 pp. Lindb. in Oef 
Sv. Vet.-Akad. Foerh. XViii, 375, nomen ta sere 
p Selpetigp between Hypnodendron and Mniodendron is by 
arly d 
considered the cnt genus to be allied to Thamnium, while he 
referred Mniodendron to the Bartramiaceae. As understood by 
Brotherus, indeed, they appear peculiarly ill defined, since the main 
