Page images

all the Nearctic and Palaearctic regions as far as the Atlas Mountains, the Indo-Chinese sub-region in the mountains, and to Hainan and Formosa; Helarctos, the Malay or sun-bear (1 species) confined to the Indo-Malayan sub-region; Melursus or Prochilus, the honey-bear (1 species), confined to the first and second Oriental sub-regions, over which it ranges from the Ganges to Ceylon; and Tremarctos, the spectacled bear-commonly known as Ursus ornatus—which is isolated in the Andes of Peru and Chili, and forms a distinct group.

Fossil Ursidae. Two bears (Ursus spelous and U. priseus) closely allied to living species, abound in the Post-tertiary deposits of Europe; and others of the same age are found in North America, as well as an extinct genus, Arctodus.

Ursus arvernensis is found in the Pliocene formation of France, and the extinct genus Leptarchus in that of North America.

Several species of Amphicyon, which appears to be an ancestral form of this family, are found in the Miocene deposits of Europe and N. India; while Ursus also occurs in the Siwalik Hills and Nerbudda deposits.

[blocks in formation]
[merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors]

The Morse, or Walrus (Trichecus rosmarus), which alone constitutes this family, is a characteristic animal of the North Polar regions, hardly passing south of the Arctic circle excepton the east and west coasts of North America, where it sometimes reaches Lat. 60°. It is most abundant on the shores of Spitzbergen, but is not found on the northern shores of Asia between Long, 80° and 160° E, or on the north shores of America from 100° to 150° west.

Its remains have been found fossil in Europe as far south as France, and in America as far as Virginia; but the small fragments discovered may render the identification uncertain.

FAMILY 35–PHOCIDAE. (13 Genera, 21 Species)

GENERAL Distribution.

NEotropical, NEARCTIC PALEARCTIC ETHIoPIAN: ORIENTAL Australian SUB-REGIONs. SUB-REgloss. SUB-REGIows. | Sub-Regions. | Sub-Regions. Sub-Regions. 1 – 4-2 -- *| as a -----|-as

The earless or true Seals are pretty equally divided between the Northern and Southern Hemispheres, frequenting almost exclusively the temperate and cold regions, except two species said to occur among the West Indian islands. The genus Phoca and its close allies, as well as Halichorus and Pelagius, are northern; while Stenorhynchus and Morunga, with their allies, are mostly southern. The genera admitted by Dr. Gray in his catalogue are as follows:– Callocephalus (3 species), Greenland, North Sea, also the Caspian Sea, and Lakes Aral and Baikal; Pagomys (2 species), North Sea, North Pacific, and Japan; Pagophilus (2 species), North Pacific and North Atlantic; Halicyon (1 species), North West coast of America; Phoca (2 species), North Atlantic and North Pacific, Japan; Halichorus (1 species), Greenland, North Sea, and Baltic ; Pelagius (2 species), Madeira, Mediterranean, Black Sea; Stenorhynchus (1 species), Antarctic Ocean, Falkland Islands, New Zealand; Lobodon (1 species), Antarctic Ocean; Leptomy” (1 species), Antarctic Ocean, South Australia, East Patagonia; Ommatophoca (1 species), Antarctic Ocean; Morunga (2 species), California, Falkland Islands, Temperate regions of Southern Ocean; Cystophora (2 species), North Atlantic, Antilles. Fossil Seals—Remains of living species of seals have been found in Post-tertiary deposits in many parts of Europe and in Algeria, as well as in New Zealand. Pristophoca occitana is a fossil seal from the Pliocene of Montpellier, while a species of Phoca is said to have been found in the Miocene deposits of the United States.


General Remarks on the Distribution of the Carnivora.

Terrestrial Carnivora-For the purposes of geographical distribution, the terrestrial and aquatic Carnivora differ too widely to be considered in one view, their areas being limited by barriers of a very different nature. The terrestrial Carnivora form a very extensive and considerably varied group of animals, having, with the doubtful exception of Australia, a world-wide distribution. Yet the range of modification of form is not very great, and the occurrence of three families consisting of but one species each, is an indication of a great amount of recent extinction. One of the most marked features presented by this group is its comparative scarcity in the Neotropical region, only four families being represented there (not counting the Ursidae, which has only one Andean species), and both genera and species are few in number. Even the Procyonidae, which are especially South American, have but two genera and six species in that vast area. We might therefore, from these considerations alone, conclude that Carnivora are a development of the northern hemisphere, and have been introduced into the Neotropical region at a comparatively recent epoch. The claim of the Nearctic region to be kept distinct from the Palaearctic (with which some writers have wished to unite it) is well maintained by its possession of at least six species of Mephitis, or skunk, a group having no close allies in any other region,-and the genera Procyon and Bassaris–for the latter, ranging from the high lands of Guatemala and Mexico to Texas and California, may be considered a Nearctic rather than a Neotropical form. In the other families, the most marked feature is the total absence of Ursidae from the Ethiopian region. The great mass of the generic forms of Carnivora, however, are found in the Oriental and Ethiopian regions, which possess all the extensive group of Viverridae (except a few species in the fourth Palaearctic subregion) and a large number of Felidae and Mustelidae. Aquatic Carnivora.-The aquatic Carnivora present no very marked features of distribution, except their preference for cold and temperate rather than tropical seas. Their nearest approximation to the terrestrial group, is supposed to be that of the Otariidae to the Ursidae; but this must be very remote, and the occurrence of both seals and bears in the Miocene period, shows, that until we find some late Secondary or early Tertiary formation rich in Mammalian remains, we are not likely to get at the transition forms indicating the steps by which the aquatic Carnivora were developed. The most interesting special fact of distribution to be noticed, is the occurrence of seals, closely allied to those inhabiting the northern seas, in the Caspian, Lake Aral, and Lake Baikal. In the case of the two first-named localities there is little difficulty, as they are connected with the North Sea by extensive plains of low elevation, so that a depression of less than 500 feet would open a free communication with the ocean. At a comparatively recent epoch, a great gulf of the Arctic ocean must have occupied the valley of the Irtish, and extended to the Caspian Sea; till the elevation of the Kirghiz Steppes cut off the communication with the ocean, leaving an inland sea with its seals. Lake Baikal, however, offers much greater difficulties; since it is not only a fresh-water lake, but is situated in a mountain district nearly 2,000 feet above the sea level, and entirely separated from the plains by several hundred miles of high land. It is true that such an amount of submergence and elevation is known to have occurred in Europe so recently as during the Glacial period; but Lake Baikal is so surrounded by mountains, that it must at that time have been filled with ice, if at anything like its present elevation. Its emergence from the sea must therefore have taken place since the cold epoch, and this would imply that an enormous extent of Northern Asia has been very recently under water. We are accustomed to look on Seals as animals which exclusively inhabit salt water; but it is probably from other causes than its saltness that they usually keep to the open sea, and there seems no reason why fresh-water should not suit them quite as well, provided they find in it a sufficiency of food, facilities for rearing their young, and freedom from the attacks of enemies. As already remarked in vol. i. p. 218, Mr. Belt's ingenious hypothesis (founded on personal examination of the Siberian Steppes), that during the Glacial period the northern ice-cap dammed up the waters of the northward flowing Asiatic rivers, and thus formed a vast fresh-water lake which might have risen as high as Lake Baikal, seems to offer the best solution of this curious problem of distribution. Range of Carnivora in Time–Carnivora have been found in all the Tertiary deposits, and comprise a number of extinct genera and even families. Several genera of Canidae occur in the Upper Eocene of Europe; but the most remarkable fact is, that even in the Lower Eocene are found two well-marked forms, Palaeonyctis, one of the Viverridae, and Arctocyon, forming a distinct family type of very generalized characters, but unmistakably a carnivore. This last has been found at La Fère, in the north-east of France, in a deposit which, according to M. Gaudry, is the very lowest of the Lower Eocene formation in Europe. Arctocyon is therefore one of the oldest, if not the very oldest, of the higher forms of mammal yet discovered.

« EelmineJätka »