XV. THE CHILI AND PERU REGION.

EXTENT. A peculiar and well-defined region, but still far from productive. It includes a narrow strip between the Cordilleras and the Pacific Ocean from Cape Blanco in 4o S. lat. to the oblique line stretching from 36° S. lat. on the coast of Chili to Port St. Antonio on the opposite side. Both limits are well marked; at the northern the forest of the adjacent region commences suddenly, and at the southern, around Conception, rapidly appear those numerous genera, which establish so strong a relation between the Patagonia Region and the temperate latitudes of the northern hemisphere. Some doubts may arise whether the Andes of its southern part should not be included, and I am disposed to think they ought, but at present it is impossible to trace the exact relations. The two islands of Juan Fernandez also belong here.

PHYSICAL CHARACTERS.-The flank of the Cordilleras regarding the Pacific is composed chiefly of porphyritic rocks, but the somewhat inclined plane which slopes towards the ocean is formed by deposits of clay, both tertiary and recent, very frequently inclosing shells, and resting on a substratum of brown sandstone. The surface may be divided into the valleys and the intervening ridges; the former containing some soil, and a supply of water near which is assembled the entire vegetation, whilst the spaces between are usually quite bare, or only support some straggling brushwood. The soil in the exposed places contains a large proportion of salt, both of nitrate of potash and chloride of sodium, which lies in a thin stratum one or two inches beneath the surface and can be easily removed in solid thin cakes. This

admixture renders the soil very puffy, and after being moistened by the heavy dews it forms a thin brittle crust. It also deprives it of the customary cohesion, and wherever the soil has collected, as on the sides of the hills and valleys, the foot readily sinks six or eight inches.

CLIMATE. Though much is within the tropics, it has few corresponding features. The temperature of the intertropical part is warm during the dry season, but is unusually cold and chilly at the opposite period; it has thus a great range. Rain is a novelty almost throughout, and instead there are dense falling mists, called garuas, from May to August, which render the weather particularly unpleasant. In the northern part these cease with great suddenness, for in the Bay of Guayaquil the rains are very heavy, and at Tumbez, within half a degree, a shower is not seen for years together. To the south the two are gradually shaded off into each other, and at Valparaiso the rainy season is short and less regular, whilst at times there is something like the garuas. The absence of regular rain has been attributed to the south wind, which blows with much constancy; and it has been observed that during the season of mists a light breeze from the opposite quarter is not unfrequent. At Valparaiso the temperature is more in accordance with its geographical position; it is situated in 33o S. lat., and during June and July, the two most unfavourable months, the range was from 46° to 64° the dews extremely heavy, but rain fell latterly.

FLORA.-Nothing that can be called forest exists, a few trees only being scattered sparingly about, and though much is within the tropic, corresponding characters are not strong. Cocos chilensis has a few individuals scattered about the valleys in the neighbourhood of Val

paraiso, and the potato may be seen here growing wild on some of the hills; a species of bambusa is not uncommon, and a salix is frequent in the valleys. The chief tree is cordia decandra, but many spots are not deficient in cultivated fruit trees. The plants recalling tropical features are azara serrata, krameria cistoidea, coriaria ruscifolia, cassia sp., mimosa cavenia, loasa acerifolia, amirola glandulosa, and croton lanceolatus. Cereus, opuntia, euphorbia, lobelia, calceolaria, and oxalis, are common. About Valparaiso are low thickets of shrubby composite; and amaryllideæ and irideæ are numerous. On waste ground near Lima tropæolum majus abounds, with sida, datura, cestrum, alternanthera, cenothera, asclepias, and calceolaria. In a few favoured valleys the ground is quite yellow with the multitudes of flowers of pancratium amencaes, whose expanding flowers are the signal for the commencement of the revels bearing its name.

RELATIONS.-The most interesting will be with the California Region, with which there is much similarity in climate, and some in productions through ageratum, mimulus, castilleja, rhus, ribes, berberis, and laurus. The prevalence of bulbous plants in Chili confers some resemblance with the South Africa Region.

EXTENT. That portion of South America between the Andes and the mouth of the Rio Plata is composed entirely of this peculiar district. To the north it extends to the neighbourhood of the towns of the interior, and approaches the river Paraguay; its exact outline is here imperfectly known. To the south it terminates in an

oblique line, extending from the Port of San Antonio to 36° S. latitude on the west coast.

PHYSICAL CHARACTERS.-A vast plain stretches on all sides, very slightly raised above the level of the sea, and only diversified in a few places by low hills. Some unimportant rivers have their origin, and are often again lost in the soil. Reddish marl is mentioned as occurring, but is not perhaps general. To the south the soil is impregnated with saline matter.

CLIMATE. The seasons are temperate, and their alternations produce a rapid change in the vegetation.

FLORA.-The remarks of Sir Francis Head on the

features are appropriate. "The great plain of Pampas of the Cordillera is about 900 miles broad, and the part which I have visited, though in the same latitude, is divided into regions of different climate and produce. On leaving Buenos Ayres, the first of these regions is covered, for 180 miles with clover and thistles; the second, which extends for 430 miles, produces long grass; and the third region, which reaches the base of the Cordillera, is a grove of low trees and shrubs. The second and third of these regions have nearly the same appearance throughout the year; for the trees and shrubs are evergreens; and the immense plain of grass only changes its colour from green to brown; but the first region varies with the four seasons of the year, in a most extraordinary manner. winter, the leaves of the thistles are large and luxuriant, and the whole appearance of the country has the rough appearance of a turnip field. The clover, at this season, is extremely rich and strong; and the sight of the wild cattle, grazing at full liberty in such pasture, is beautiful. In spring, the clover has vanished, the foliage of the thistle has extended across the ground, and the country still looks as if covered with a rough crop of turnips. In

In

less than a month the change is most extraordinary; the whole region becomes luxuriant with enormous thistles, which have suddenly shot up to a height of ten or eleven feet, and are in full bloom. * * * The summer is not over before the scene undergoes another change; the thistles suddenly loose their sap and verdure; their heads droop, the leaves shrink and fade, the stems become black and dead, and they remain rattling with the breeze one against another, until the violence of the pampero or hurricane levels them with the ground, where they rapidly decompose and disappear; the clover rushes up, and the scene is again verdant." Ranunculaceæ, caryophylleæ, and cruciferæ, make their appearance, and the low bushes are most probably chiefly compositæ. Species of lathyrus, polygala, anemone, oxalis, lobelia, galium, plantago, and teucrium, are also frequent.

RELATIONS.-There is a strong connexion with some of the European Regions through numerous genera, and some slight alliance with the South Africa Region. It is curious that an exotic thistle, cynara cardunculus, should have taken such entire possession of a large district, as to have obliterated nearly the whole of the spontaneous vegetation. Its luxuriance is so great, that the question arises, whether plants can ever find a situation more favourable to their existence than that in which nature has placed them? The excessive developement also of psidium pomiferum, at Tahiti, would seem to require an affirmative. In general character there is some similarity with the Prairie Region, but the minuter features are different, and the latter is less fertile.