« EelmineJätka »
Order, Family, and
Range within the Region.
Range beyond the Region.
TETRAONIDÆ. 126. Cyrotonyx .. 1 S. Central States
Mexico and Guatemala 127. Ortyx ... ... 5 All United States and to Canada Mexico to Honduras and
Costa Rica 128. Callipepla .. i California
Mexico 129. Lophortyx ... Arizona and California 130. Oreortyse
California and Oregon 131. Tetrao ... ... N. and N. W. America
Palæarctic 132. Centrocercus ... 1 Rocky Mountains 133. Pediocektes ... N. and N. W. America 134. Cupidonia ... 1 | E. & N. Cen. States and Canada 135. Bonasa... ... N. United States and Canada Palæarctic 136. Lagopus.., ... 4 Arctic zone and to 39° N. Lat. Palæarctic
in Rocky Mountains
| United States to 40° N. Lat. Neotropical 139. Psuedogryphis United States to 49' N. Lat. Neotropical
FALCONIDÆ. 140. Polyborus ...
1 s. States to Florida & California Neotropical 141. Circus ... .. 1 All N. America
Nearly cosmopolite 142. Antenor... ... 2 California and Texas
Neotropical 143. Astur ... ... 1 All N. America
Almost cosmopolite 144. Accipiter
3 All temperate N. America Almost cosmopolite 145. Tachytriorchis New Mexico to California Neotropical 146. Buteo 12 | All N. America
All regs. but Australian 147. Archibuteo 3 All N. America
N. Palæarctic 148. Asturina S. E. States
Neotropical 149. Aquila... The whole region
Palæarc., Ethiop., Indian 150. Haliæetus ... 2 All N. America
All regs. but Neotropical 151. Nauclerus ..., E. coast to Pennsylvania and Neotropical
Wisconsin (Rostrhamus Florida)
Neotropical 152. Elanus ... ...
Southern and Western States Tropical regions 153. Ictinia ... ... Southern States
Neotropical 154. Falco The whole region
Almost cosmopolite 155. Hierofalco N. of N. America
N. Palearctic 156. Cerchneis | All N. America
PANDIONIDÆ. 157. Pandion...... | 1
Temperate N. America
SUMMARY OF THE PAST CHANGES AND GENERAL RELATIONS OF
THE SEVERAL REGIONS.
HAVING now closed our survey of the animal life of the whole earth—a survey which has necessarily been encumbered with a multiplicity of detail-we proceed to summarize the general conclusions at which we have arrived, with regard to the past history and mutual relations of the great regions into which we have divided the land surface of the globe.
All the palæontological, no less than the geological and physical evidence, at present available, points to the great land masses of the Northern Hemisphere as being of immense antiquity, and as the area in which the higher forms of life were developed. In going back through the long series of the Tertiary formations, in Europe, Asia, and North America, we find a continuous succession of vertebrate forms, including all the highest types now existing or that have existed on the earth. These extinct animals comprise ancestors or forerunners of all the chief forms now living in the Northern Hemisphere; and as we go back farther and farther into the past, we meet with ancestral forms of those types also, which are now either confined to, or specially characteristic of, the land masses of the Southern Hemisphere. Not only do we find that elephants, and rhinoceroses, and hippopotami, were once far more abundant in Europe than they are now in the tropics, but we also find that the apes of West Africa and Malaya, the lemurs of Madagascar, the Edentata of Africa and South America, and the Marsupials of America and Australia, were all represented in Europe (and probably also in North America) during the earlier part of the Tertiary epoch. These facts, taken in their entirety, lead us to conclude that, during the whole of the Tertiary and perhaps during much of the Secondary periods, the great land masses of the earth were, as now, situated in the Northern Hemisphere; and that here alone were developed the successive types of vertebrata from the lowest to the highest. In the Southern Hemisphere there appear to have been three considerable and very ancient land masses, varying in extent from time to time, but always keeping distinct from each other, and represented, more or less completely, by Australia, South Africa, and South America of our time. Into these flowed successive waves of life, as they each in turn became temporarily united with some part of the northern land. Australia appears to have had but one such union, perhaps during the middle or latter part of the Secondary epoch, when it received the ancestors of its Monotremata and Marsupials, which it has since developed into a great variety of forms. The South African and South American lands, on the other hand, appear each to have had several successive unions and separations, allowing first of the influx of low forms only (Edentata, Insectivora, and Lemurs); subsequently of Rodents and small Carnivora, and, latest of all, of the higher types of Primates, Carnivora, and Ungulata.
During the whole of the Tertiary period, at least, the Northern Hemisphere appears to have been divided, as now, into an Eastern and a Western continent; always approximating and sometimes united towards the north, and then admitting of much interchange of their respective faunas; but on the whole keeping distinct, and each developing its own special family and generic types, of equally high grade, and generally belonging to the same Orders. During the Eocene and Miocene periods, the distinction of the Palæarctic and Nearctic regions was better marked than it is now; as is shown by the floras no less than by the faunas of those epochs. Dr. Newberry, in his Report on the Cretaceous and Tertiary floras of the Yellowstone and Missouri Rivers, states, that although the Miocene flora of Central North
America corresponds generally with that of the European Miocene, yet many of the tropical, and especially the Australian types, such as Hakea and Dryandra, are absent. Owing to the recent discovery of a rich Cretaceous flora in North America, probably of the same age as that of Aix-la-Chapelle in Europe, we are able to continue the comparison; and it appears, that at this early period the difference was still more marked. The predominant feature of the European Cretaceous flora seems to have been the abundance of Proteaceæ, of which seven genera now living in Australia or the Cape of Good Hope have been recognised, besides others which are extinct. There are also several species of Pandanus, or screw-pine, now confined to the tropics of the Eastern Hemisphere, and along with these, oaks, pines, and other more temperate forms. The North American Cretaceous flora, although far richer than that of Europe, contains no Proteaceæ or Pandani, but immense numbers of forest trees of living and extinct genera. Among the former we have oaks, beeches, willows, planes, alders, dog-wood, and cypress; together with such American forms as magnolias, sassafras, and liriodendrons. There are also a few not now found in America, as Araucaria and Cinnamomum, the latter still living in Japan. This remarkable flora has been found over a wide extent of country-New Jersey, Alabama, Kansas, and near the sources of the Missouri in the latitude of Quebec—so that we can hardly impute its peculiarly temperate character to the great elevation of so large an area. The intervening Eocene flora approximates closely, in North America, to that of the Miocene period; while in Europe it seems to have been fully as tropical in character as that of the preceding Cretaceous period; fruits of Nipa, Pandanus, Anona, Acacia, and many Proteaceæ, occurring in the London clay at the mouth of the Thames. .
These facts appear, at first sight, to be inconsistent, unless we suppose the climates of Europe and North America to have been widely different in these early times ; but they may perhaps be harmonised, on the supposition of a more uniform and a somewhat milder climate then prevailing over the whole Northern Hemisphere; the contrast in the vegetation of these countries