to its terminus, where it mingles with the Ceylonese Subregion, which includes Ceylon and the extremity of the Indian Peninsula. It is rich in animal life, which, as a whole, is Oriental in its affinities. The Mediterranean (Palearctic) Subregion seems to extend eastward to the arid valley of the Indus, and India thus possesses several Ethiopian forms, which have led some zoölogists to regard its fauna as Ethiopian rather than Oriental, but the weight of opinion has turned against this view. The eastern shore of the Bay of Bengal is the home of so mixed an animal population that it has sometimes been called an ‘Indo-Malayan’ subregion, but this is not generally recognized. Northeastern India, along the midslopes of the southern Himalaya ranges, is very different, faunistically, from the peninsular plains or the low hot coastal regions, owing to its elevation, and forms a long westward-reaching tongue of the Indo-Chinese and Manchurian subregions (q.v.). See maps under Distribution of Animals; and the paragraph on Fauna, under India.
INDIAN SUMMER. A short season of pleasant weather in the Central and Atlantic Coast States, usually occurring in October or November, more rarely in December, and characterized by an almost cloudless sky, calm or light airs, a hazy atmosphere, and mild temperature in the daytime, but rather cool at night. It may last one or two weeks, and may recur two or three times during a season, but rarely more than twice. During Indian summer weather the barometer stands above the average, and the cloudless sky indicates that there is in general a descending tendency of the air at some distance above the earth. Balloons ascending to great heights show that there is very little horizontal movement in the air, but what there is is toward the east. At this season the leaves of most plants dry up and drop away, adding their debris to the dust in the atmosphere. Owing to the prevailing dryness, forest fires and prairie fires occur at this time, and the smoke adds to the intensity of the Indian summer haze, but is not necessarily the sole cause of it. Frequently such smoke spreads slowly eastward, gathers moisture to itself, and is followed by clouds and gentle rain. Precisely similar weather occurs in Germany, where it is known as the ‘Old Woman's Summer’ and ‘Saint Luke's Summer,’ and in England, where it is known as ‘Saint Martin's Summer,’ or ‘All Hallow Summer’; these terms being applied to it according to the various dates on which it happens to occur in October or November. There are also many indications of its existence in China and Siam. The haze attending the African Harmattan in December and January appears very similar to that of Indian summer, but the diatom dust that characterizes the former has not yet been found in the latter. As to the origin of this expression, Mr. Albert Matthews has shown that it does not occur anywhere either in printed books or manuscripts until the year 1794; but at that time it was in use throughout the Atlantic States. The popular belief that Indian summer weather was predicted by the native Indians in conversation with the first European settlers finds no documentary corroboration, and the idea that the term Indian summer was employed by the early settlers seems to be a myth. In general, neither this term nor anything corresponding to it is to be found in any Indian language. The term Indian summer in its present usage was introduced into England from America. In 1778 Horace Walpole used the same expression, but he evidently had in mind the intense heats of the midsummer weather in India and the West Indies. For full information on the whole subject, see the Monthly Weather Review, vol. xxx., pp. 19-29 and 69-79 (Washington, 1902).
INDIAN TERRITORY. A Territory of the United States, situated nearly in the middle of the country. It is bounded on the north by Kansas and Oklahoma, on the east by Missouri and Arkansas, on the south by Texas, and on the west by Oklahoma. Its area is, approximately, 31,000 square miles (census of 1900).
Because the Indian Territory had been reserved for Indian tribes, it long remained practically unexplored, while the areas around it were surveyed and well mapped. A curious illustration of the fact that little was known about this large region was afforded by the survey of the lands of the Territory authorized by the National Congress in 1894. It had been assumed that the Territory was mainly an open, flat country, and that the survey might therefore proceed very rapidly. It was found, however, that about one-fourth of the Territory is mountainous, and that nearly two-thirds is woodland. As late as 1895 it appeared that while good maps of the drainage of the Chickasaw reservation had been prepared, its relief was not yet mapped; and that little was known either of the drainage or relief of the remainder of the Territory.
Various parts of the Territory differ much in their topography. South of the Canadian River, in the reservations of the Choctaw and Chickasaw nations, the country is considerably broken, being traversed by the winding serpentine ridges forming the southern part of the Ozark Hills. These hills enter the Territory from Arkansas, and the summits near the Arkansas boundary reach an altitude of 2500 feet above the sea. Farther south they diminish in height till, in the middle of the Choctaw reservation, they are not more than 1000 feet above the general level of the country. The rocks of these ridges are, for the most part, quartzite, while the valleys between them are floored with limestone. This difference in the rock formations explains the topography. The quartzite ridges are the survival of the hardest rocks.
The northeastern part of the country, north of the Arkansas and Canadian rivers, is a plateau deeply scored by streams. West of this very broken region the Territory is broadly undulating. The eastern portion of the Territory, particularly in the hilly and mountainous regions, is heavily timbered. The southern part, including the Chickasaw reservation and the western portion of the Choctaw country, is a territory of timber and prairie, the timber predominating to the extent of nearly three-fourths of the area. The largest extent of prairie is in the Cherokee and Creek reservations of the north, where there is little timber except along the streams between the timber belt on the west and the hilly country on the east. Some Azoic rocks are found in the north, and the igneous rocks of the hilly and mountainous areas are above mentioned, but the predominant geological formation is Carboniferous; in this formation are the bituminous coal measures that will probably always be the chief
