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often beautifully marked with transverse bars. Itis highly hygro- 
metric, but not equally so on both sides, so that the teeth close over 
the mouth of the capsule, when damp and spread out when dry. 
Their office, no doubt, is toaid in the dispersion of the spores and the 
provision made for this purpose is certainly remarkable. The teeth, 
in some genera are long, in others, short,—in some, obtuse, in others, 
acute,—in some, triangular, in others, lance-shaped,—in some, 
entire, in others, cleft,—in some, rigid, in others, frail,—in some, 
straight, in others, twisted—and so forth. Not a few genera take 
their names from some peculiarity in the peristomial teeth, for 
instance,—Dicranum (a fork), the 16 teeth being cleft so as to re- 
semble forks. Ditrichum (two hairs), the 16 teeth, being cleft to 
the base into two thread-like portions—Brachydontium (short tooth) 
the teeth being quite short. Didymodon (twin tooth), the 16 teeth 
being cleft to the base into two nearly equal awl-shaped ‘“ legs ”— 
Tortula (twisted), the teeth being long and (like the leaves of the 
plant when dry) strongly twisted, just as you would twist together 
a number of threads between your thumb and finger. Ceratodon 
(a horn tooth), the 16 cleft teeth resembling goat’s horns. 
Dichodontium (to divide a tooth), the teeth being cleft to below the 
middle into two or three ‘‘legs.’’ All genera, however, do not get 
their names from the form of the peristome, for example, Swartzia, 
is named after Schwartz; Blindia, after Blind; Georgia, after 
George III.; Catharinea, after Catherine II. of Russia; Pottia, 
after Pott; Buxbaumia, after Buxbaum; Seligeria, after Seliger. 
Again, ‘‘ Polytrichum”’ (many hairs) has reference to the shaggy 
appearance of the Calyptra and ‘‘Atrichum” (no hairs), to the absence 
of hairs on the Calyptra. ‘‘ Ephemerum” reminds us of the brief 
life of the species, and ‘‘ Acaulon”’ (without a stem) tells us of 
stemless mosses. ‘‘Gymnostomum” (naked mouth), points to 
certain mosses that have no peristome. The specific names of mosses 
may refer toindividuals or to some favourite habitat or some charac- 
teristic of growth, or to a dozen other things, for instance, we have 
Pottia Wilsoni, Georgia Brownii, Pottia lanceolata, Dicranum 
palustre, Barbula muralis, Ceratodon purpureus, and so forth. 
Let us return, for a minute, to the peristome, just to add a word 
as to its colour. This is ofimportance, as is also that of the 
seta. In each case it may range from quite a pale yellow to deep 
orange or purple. In the Polytrichums we cannot see the 32 or 
_ 64 teeth as they are underneath a membrane called an epiphragm 
‘This membrane, which seems to be a flattened top to the columella, 
is very characteristic of the genus. We must not stop for any 
further remarks on the spores but press on to note that few plants 
_ (if indeed any) reproduce themselves in so many ways as mosses. A 
single spore can, through the protonema, produce a large number 
