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The Octodontidae include a number of curious and obscure rat-like animals, mostly confined to the mountains and open plains of South America, but having a few stragglers in other parts of the world, as will be seen by our notes on the genera. The most remarkable point in their distribution is, that two genera are peculiar to the West Indian islands, while no species of the family inhabits the northern half of South America. The distribution of the genera is as follows:--Habrocomus (2 sp.), Chili; Capromys (3 sp.), two of which inhabit Cuba, the third Jamaica (Plate XVII, vol. ii. p. 67); Plagiodontia (1 sp.), only known from Hayti; Spalacopus, including Schizodon (2 sp.), Chili, and east side of Southern Andes ; Octodon (3 sp.), Peru, Bolivia, and Chili; Ctenomys (6 sp.), the tuco-tuco of the Pampas, the Campos of Brazil to Bolivia and Tierra del Fuego; Ctenodactylus (1 sp.), Tripoli, North Africa ; Pectinator (1 sp.), East Africa, Abyssinia, 4,000 to 5,000 feet.

Capromys and Plagiodontia, the two West Indian genera, were classed among the Echimyidæ by Mr. Waterhouse, but Professor Lilljeborg removes them to this family.

Extinct Octodontidæ.—Species of Ctenomys have been found in the Pliocene of La Plata, and an extinct genus Megamys, said to be allied to Capromys, in the Eocene of the same country. In Europe, Palæomys and Archæomys from the lower Miocene of Germany and France, are also said to be allied to Capromys..

FAMILY 65.—ECHIMYIDÆ. (10 Genera, 30 Species.)

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The Echimyidæ, or spiny rats, are a family, chiefly South American, of which the Coypu, a large beaver-like water-rat from. Peru and Chili is the best known. Two of the genera are found in South Africa, but all the rest inhabit the continent of South America, East of the Andes, none being yet known north

of Panama. The genera are as follows :

-Dactylomys (2 sp.), Guiana and Brazil ; Cercomys (1 sp.), Central Brazil ; Lasiuromys (1 sp.), San Paulo, Brazil; Petromys (1 sp.), South Africa; Myopotamus (1 sp.), the coypu, on the East side of the Andes from Peru to 42° S. lat., on the West side from 33° to 48° S. lat. ; Carterodon (1 sp.), Minaes Geraes, Brazil; Aulacodes (1. sp.), West and South Africa; Mesomys (1 sp.), Borba on the Amazon ; Echimys (11 sp.), from Guiana and the Ecuadorian Andes to Paraguay; Loncheres (10 sp.), New Granada to Brazil.

Fossil and Extinct Echimyido. —The genus Carterodon was established on bones found in the Brazilian caves, and it was several years afterwards that specimens were obtained showing the animal to be a living species. Extinct species of Myopotamus and Loncheres have also been found in these caves, with the extinct genera Lonchophorus and Phyllomys.

No remains of this family have been discovered in North Arnerica ; but in the Miocene and Upper Eocene deposits of France there are many species of an extinct genus Theridomys, which is said to be allied to this group or to the next (Cercolabidæ). Aulacodon, from the Upper Miocene of Germany, is allied to the West African Aulacodes; and some other remains from the lower Miocene of Auvergne, are supposed to belong to Echimys.

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The Cercolabidæ, or arboreal porcupines, are a group of rodents entirely confined to America, where they range from the northern limit of trees on the Mackenzie River, to the southern limit of forests in Paraguay. There is however an intervening district, the Southern United States, from which they are absent. Erethizon (3 sp.), the Canadian porcupine, is found throughout

Canada and as far south as Northern Pennsylvania, and west to the Mississippi (Plate XX., vol. ii. p. 135); an allied species inhabiting the west coast from California to Alaska, and inland to the head of the Missouri River; while a third is found in the north-western part of South America; Cercolabes (12 sp.), ranges from Mexico and Guatemala to Paraguay, on the eastern side of the Andes; Chatomys (1 sp.), North Brazil.

Extinct Cercolabida.-A large species of Cercolabes has been found in the Brazilian caves, but none have been discovered in North America or Europe. We may conclude therefore that this is probably a South American type, which has thence spread into North America at a comparatively recent epoch. The peculiar distribution of Cercolabes may be explained by supposing it to have migrated northwards along the west coast by means of the wooded slopes of the Rocky Mountains. It could then only reach the Eastern States by way of the forest region of the great lakes, and then move southward. This it may be now doing, but it has not yet reached the Southern States of Eastern North America.

FAMILY 67.--HYSTRICIDÆ (3 Genera, 12 Species.)

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The true Porcupines have a very compact and well-marked distribution, over the whole of the Oriental and Ethiopian regions (except Madagascar), and the second Palæarctic sub-region. There is some confusion as to their sub-division into genera, but the following are those most usually admitted :—Hystrix (5 sp.), South Europe to the Cape of Good Hope, all India, Ceylon, and South China ; Atherura (5 sp.), “ brush-tailed porcupines,” inhabit West Africa, India, to Siam, Sumatra, and Borneo ; Acanthion (2 sp.), Nepal and Malacca, to Sumatra, Borneo, and Java.

Extinct Hystricidæ.-Several extinct species of Hystrix have

been found in the Pliocene and Miocene deposits of Europe, and one in the Pliocene of Nebraska in North America.

FAMILY 68.—CAVIIDÆ. (6 Genera, 28 Species.)

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The Cavies and Agoutis were placed in distinct families by Mr. Waterhouse, in which he is followed by Professor Carus, but they have been united by Professor Lilljeborg, and without pretending to decide which classification is the more correct I follow the latter, because there is a striking external resemblance between the two groups, and they have an identical distribution in the Neotropical region, and with one exception are all found east of the Andes. Dasyprocta (9 sp.), the agouti, ranges from Mexico to Paraguay, one species inhabiting the small West Indian islands of St. Vincent, Lucia, and Grenada ; Calogenys (2 sp.), the paca, is found from Guatemala to Paraguay, and a second species (somewhat doubtful) in Eastern Peru; Hydrochorus (1 sp.), the capybara, inhabits the banks of rivers from Guayana to La Plata; Cavia (9 sp.), the guinea-pigs, Brazil to the Straits of Magellan, and one species west of the Andes at Yça in Peru ; Kerodon (6 sp.), Brazil and Peru to Magellan ; Dolichotis (1 sp,), the Patagonian cavy, from Mendoza to 48° 30' south latitude, on sterile plains.

Extinct Caviide.Hydrochorus, Calogenys, Dasyprocta, and Kerodon, have occurred abundantly in the caves of Brazil, and the last-named genus in the Pliocene of La Plata. Hydrochærus has been found in the Post-Pliocene deposits of South Carolina. Cavia and Dasyprocta are said to have been found in the Miocene of Switzerland and France. No well-marked extinct genera of this family have been recorded.

If the determination of the above-mentioned fossil species of Cavia and Dasyprocta are correct, it would show that this now

exclusively South American family is really derived from Europe, where it has long been extinct.

FAMILY 69.—LAGOMYIDÆ. (1 Genus, 11 Species.)

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The Lagomyidæ, or pikas, are small alpine and desert animals which range from the south of the Ural Mountains to Cashmere and the Himalayas, at heights of 11,000 to 14,000 feet, and northward to the Polar regions and the north-eastern extremity of Siberia. They just enter the eastern extremity of Europe as far as the Volga, but with this exception, seem strictly limited to the third Palæarctic sub-region. In America they are confined to the Rocky Mountains from about 42° to 60' north latitude.

Extinct Lagomyida.--Extinct species of Lagomys have occurred in the southern parts of Europe, from the Post-Pliocene to the Miocene formations. Titanomys, an extinct genus, is found in the Miocene of France and Germany.

FAMILY 70.—LEPORIDÆ. (1 Genus, 35-40 Species.)

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The Hares and Rabbits are especially characteristic of the Nearctic and Palæarctic, but are also thinly scattered over the Ethiopian and Oriental regions. In the Neotropical region they are very scarce, only one species being found in South America, in the mountains of Brazil and various parts of the Andes, while one or two of the North American species extend into Mexico

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