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minute as to be scarcely distinguishable, and so little self- 
dependant, that they never dispense with their supporting pro- 
thallium during the whole period of their existence, and the 
microscope will at once show their affinity to Funaria in the 
lax parenchymatous ar eolation and inflated calyptra. Again, 
Archidium and Pleuridium are equally approximated to 
Dicranella, while Phascum itself for which we retain the com- 
mon P. acaulon Lin. as the type is equally close to Pottia 
among the Trichostomacese. 
Habitats. 
Few localities are to be found where some moss or other is 
not to be met with. Even in our largest towns, a few yards of 
open ground, if neglected for a time, become covered with a 
crop of mosses originating from spores wafted on every breeze. 
Bryum argenteum and Ceratodon purpureus occupy the paths, 
though probably they do not bear fruit, and Tortula muralis 
takes possession of the bricks and their interstices on the garden 
walls. 
If we extend our walks to the commons around, we find 
the list of species considerably augmented, and old sandstone 
walls bear in addition Gfrimmia pulvinata, with several Tortulse 
and Brya. A few mosses are littoral or affect the sea-coast, 
especially several species of Pottia, with Trichostomum cris- 
pulum, brachydontium and littorale, Tortula nitida and cunei- 
folia. 
Again, the chemical nature of the soil or rock materially 
influences the character of its inhabitants : some are almost 
confined to chalk, as Seligeria calcarea and paucifolia, Funaria 
calcarea, several Tortulae, Weisia tortilis, Thuidium delica- 
tulum and histricosum, &c. ; while clay-fields support the 
various species of Phascum and Ephemerum. Sandstone has 
Campylostelium, Brachyodus, Tetrodontium, &c. ; and granite, 
slate, or basalt each supports some peculiar species : to the 
first of these especially are the Andreaeas attached. Bogs are 
rich in certain species, especially of Mniacese, with Hypnum 
cuspidatum, cordifolium, giganteum, fluitans, nitens, &c. 
Trees are occupied by various species of Orthotrichum, Zygo- 
don, Cryphaea, and Leucodon — some preferring the smooth- 
barked willows, others the rougher oak and elder ; and, again, 
some confine themselves to the parts near the ground — as 
Weisia truncicola, Leskea pulvinata and polycarpa, Anomodon 
viticulosus, &c. As we ascend the mountains, we soon find we 
have reached the head-quarters of the mosses — the numerous 
streams and waterfalls, and the frequent mists that saturate 
the atmosphere with moisture, keep them growing continually, 
