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often beautifully marked with transverse bars. It is 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 to aid 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-hke 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 Eussia ; Pottia, 

 after Pott ; IBuxbaumia, 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 hau's on the Calyptra. •' Ephemerum " reminds us of the brief 

 life of the species, and "Acaulon" (without a stem) telle us of 

 stemless mosses. " Gymuostomum " (naked mouth), points to 

 certain mosses that have no peristome. The specific names of mosses 

 may refer to individuals 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 of importance, 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 epiphraym 

 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) re/>rodMC(? themselves in so many ways as mosses. A 

 single spore can, through the protonema, produce a large number 



