common in the winter. At times the power of the sun's rays is very great.

FLORA. The character of the vegetation varies; much is covered by a thin forest of trees, stunted, and crooked in their growth, and struggling among rugged volcanic rocks; and also by large fertile plains, sustaining a varied and abundant flora, through which run clear streams, fringed with trees of very European aspect, and many lively plants. Still there are places extremely barren, and where exposure and the absence of water have excluded all vegetation. There is, however, no want of fertility, and the variety in the climate is favourable to a multitude of fruits and vegetables. The tropical productions of the plains soon cease, and leave the region in the possession of trees, shrubs, and herbaceous plants, whose analogies are with temperate and even cold climates. Quercus has nearly twenty species, which grow through a great variety of elevation, and cease only at about 10,000 feet; one authority says 10,400, and another 9,843 feet. This genus is widely distributed through the continent; to the north we find it with deciduous leaves, on the east coast in 45o, and on the west in 47°; it soon becomes an evergreen, and ascending the mountain sides, does not cease till it has crossed the equator. Recalling that many of its species are found on the Himma-leh mountains, in Java, and other Indian islands, its partiality for low latitudes is very decided. Wheat ceases to be cultivated at the same elevation, and previously rye and barley are mixed with it. Pinus occidentalis is frequent, ranging between 6,100 and 13,000 feet, and as far south as 120 north latitude. There is another species, I believe as yet undescribed, with long cones and longer leaves. It is found around Tepic in the northern part of the region, com

mencing at 3,500 feet. Other trees and shrubs are supplied by abies hirtella, cupressus thurifera, c. sabinoides, taxodium distichum, taxus montana, alnus mexicana, salix several species, amygdalus microphylla, cheirostemon platanoides, mespilus pubescens, and several species of arbutus, arctostaphylos, vaccinium, rosa, and ribes.

RELATIONS.-With temperate Europe and America it has many genera in common, as senecio, cnicus, draba, ranunculus, anemone, arenaria, stachys, pedicularis, myosotis, polemonium, galium, cornus, and caprifolium; but a firmer connexion with the latter is established through lupinus, ageratum, and chelone; yet nearly every species is peculiar. The more peculiar genera are 'mirabilis, maurandya, leucophyllum, hoitzia, georgina or dahlia, zinnia, sckhuria, ximenesia, lopezia, vauquelinia, choisya, and cheirostemon.' It possesses, in common with other alpine regions, the negative character of having no peculiar natural family, and comparatively few genera; its individuality depends on species. Through quercus and pinus, and some of the herbaceous genera, it is connected more closely with the Himma-leh than with the Andes region.

X. THE WEST INDIA REGION.

EXTENT.-The West India Islands, the Bahamas, and the extremity of Florida, south of 27° north latitude, compose this region, which, with the exception of the latter, is the same as Schouw's. It possesses all the vigour and luxuriance of an island climate within the tropics, where moisture is ever ready in the atmosphere to feed vegetation; and the elevation of the surface, which in Cuba

attains nearly 9,000 feet, is also sufficient to produce a variety in the productions. The whole is situated between 100 and 27° north latitude.

PHYSICAL CHARACTERS. These islands vary much in their character and geological formation. They admit of a twofold division; the volcanic rising to elevated summits, covered with forest, abundantly supplied with streams of water, and very fertile, as St. Vincent, St. Lucie, Martinique, Dominica, and Guadaloupe; the others, principally composed of limestone, are low, less watered, by no means so productive, and sometimes even sterile, such as Barbadoes, Tobago, Antigua, and Barbuda. Cuba, the most extensive island, is chiefly covered with forest, and has a superficies of 54,000 square miles. A chain of mountains traverses it from east to west, which rises into several peaks, and sends many streams to the plains below. The mountain chain is composed of granite, syenite, gneiss, and mica slate, and the lower lands of secondary formations, and they are eminently fertile and productive. Jamaica has a superficies of 4,256 square miles, and the Blue Mountains, whose greatest elevation is 7,278 feet, make an agreeablo variety in the climate, and a healthy retreat for the invalid. These are chiefly composed of transition rocks, with, nearer the coast, red sandstone, marl, and limestone reposing on them. Some parts are alluvial, and generally well watered and fruitful. St. Domingo has an area of 28,000 square miles, and the central mountain peaks are lofty, La Serrania attaining 9,000 feet, and La Sella, 7,000 feet. Their flanks support noble forests, and are traced by numerous fertilizing streams. Puerto Rico contains 240 square miles, and is equally fertile with the rest. Its highest part is about 4,000 feet, and it has several fertile valleys and plains. The Bahamas comprise a

numerous group, composed of sandstone; and though the soil is generally dry and rocky, they yield some good timber.

CLIMATE. The temperature is usually equable, but must be called warm; the range is therefore inconsiderable, and the mean at different places will vary from 73o to 81°. It is only on the accession of a north wind, that much deviation occurs, and then even ice is stated to be produced, but those islands most to windward are the greatest sufferers.

FLORA.- Originally nearly the whole of this region was covered with forest; a few exceptions might only be found where tropical grasses occupied the surface. Now cultivation has removed an important portion, but extensive woods still exist. Swietenia mahagoni abounds in several islands, as does also guaicum officinale, with various species of myrtus, uvaria, laurus, and melastoma. The sameness these might otherwise produce is broken by several palmæ, and especially by the arborescent ferns, whose peculiar beauty is highly characteristic of the scenery. Ferns are generally very abundant, and assume a tropical variety of stature and habit. The most prevalent and characteristic are asplenium arboreum, cyathea arborea, c. speciosa, c. muricata, with numerous species of polypodium, pteris, aspidium, gymnogramma, acrostichum, and adiantum. A multitude of twining plants festoon the vegetation, lashing it into an impervious mass, belonging to convolvuluceæ, passifloreæ, some leguminosa, assisted by interesting kinds of paullinia and aristolochia. Orchidaceæ are very abundant, particularly the extensive genus epidendrum, and species of oncidium, bletia, catasetum, and spiranthes are also numerous.

The claims of Florida south of 27° north latitude to

be considered a part of this region, are established through tillandsia, sapindus, indigofera, chrysobalanus, rhexia, croton, jatropha, and several others.

RELATIONS.-The position of this region between the large continents of America insures an intimate relation with them, modified by its insular situation. This is, however, stronger with South than North America, perhaps arising from the moister atmosphere common to both, for there are no other circumstances which are not equally shared by the Central America region. With the South American regions it is strongly related by similar genera of palmæ, passifloreæ, orchidaceæ, plumbagineæ, cordiacea, and arborescent and herbaceous ferns. With the central America region the connexion is through ficus, a few orchidaceæ, asplenium arboreum, swietenia mahagoni, pinus occidentalis, and some others, particularly those of the sandy shores, as hippomane mancinella. There is a singular absence of quercus in the higher lands, considering how very numerous the species are in the Mexico alpine region within the same latitude. It has all the luxuriance of other insular regions within the tropics, and is unsurpassed by them in the variety of its ferns and orchidaceæ, as none others have a similar number for a given space. In the latter, the Pacific islands are much poorer, perhaps from the absence of the dense forest they appear to love. Wydleria portoriccensis and lepidium virginicum, two cruciferous plants, are found on the island, indicated by the specific name of the former.