The Chinchillidæ, including the chinchillas and viscachas, are confined to the alpine zones of the Andes, from the boundary of Ecuador and Peru to the southern parts of Chili; and over the Pampas, to the Rio Negro on the south, and the River Uruguay on the east. Chinchilla (2 sp.), the true chinchillas, are found in the Andes of Chili and Peru, south of 9° S. lat., and from 8,000 to 12,000 feet elevation (Plate XVI. vol. ii. p. [40]); Lagidium (3 sp.), the alpine viscachas, inhabit the loftiest plateaus and mountains from 11,000 to 16,000 feet, and extend furthest north of any of the family; while Lagostomus (1 sp.), the viscacha of the Pampas, has the range above indicated. The family is thus confined within the limits of a single sub-region.

Extinct Chinchillidæ.—Lagostomus has been found fossil in the caves of Brazil, and in the Pliocene deposits of La Plata. The only known extinct forms of this family are Amblyrhiza and Loxomylus, found in cavern-deposits in the island of Anguilla, of Post-Pliocene age. These are very interesting, as showing the greater range of this family so recently; though its absence from North America and Europe indicates that it is a peculiar development of the Neotropical region.

Family 64.—OCTODONTIDÆ. (8 Genera, 19 Species.)

General Distribution.
Neotropical
Sub-regions.		Nearctic
Sub-regions.		Palæarctic
Sub-regions.		Ethiopian
Sub-regions.		Oriental
Sub-regions.		Australian
Sub-regions.
1. 2 — 4— — — —— 2 — —1 — — —— — — —— — — —

The Octodontidæ 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.)

General Distribution.
Neotropical
Sub-regions.		Nearctic
Sub-regions.		Palæarctic
Sub-regions.		Ethiopian
Sub-regions.		Oriental
Sub-regions.		Australian
Sub-regions.
1. 2 — —— — — —— — — —1 — 3 —— — — —— — — —

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.