wood, where hardly a breeze penetrates to ruffle their leaves. Unlike the ferns, the size and number of which gradually diminish in passing from tropical to temperate countries, the maximum of mosses is found in cold climates, increasing in luxuriance, beauty, and abundance as we approach the North Pole. Like the ferns, moisture and shade are highly favorable to their growth and well-being; hence, as a rule, they produce a larger number of species and individuals, and spread over wider areas in islands and the vicinity of rivers and lakes than in the interior of continents, unless when well wooded and watered. Their favorite habitats appear to be rocky dells or ravines at the foot of mountains, with streamlets murmuring through them and dense trees interweaving their foliage over their sides and creating a dim twilight in the recesses beneath. In such hermit seclusions the botanist may expect to reap the richest harvest of species. Mosses, in many instances, are limited to rocks and soils of the same mineral character; their limits of distribution, and of the rocks and soils possessing such character being identical. For instance, some are confined to limestone districts and chalk cliffs; a calcareous soil being indispensable to their existence. Others affect granite; numerous species luxuriate in soil formed by the disintegration of micaceous schist; while not a few are found growing chiefly on sandstone and clay. Some are found only on and near the seashore; others are confined to the beds of streams and cliffs moistened by the spray of cascades, where, however impetuous the torrent may be, they cling tenaciously to the rocks and form carpets of greenest verdure for the white, glistening feet of the descending waters. Some are restricted exclusively to trees whose trunks and boughs they clasp like emerald bracelets; others lead a lonely, hermit-like existence in the dim moist caves and crevices of rocks, where they are discovered only by the glistening of a stray adventurous sunbeam on the drops of dew trembling upon their shining golden leaves.