It would lead us too far to attempt a description of this horde of curious and interesting rodents, so only a few of the more striking and characteristic forms can be mentioned. There are two genera of porcupines (_Coendou_ and _Chætomys_), both arboreal, which belong in the same family as the North American _Erethizon_, but are distinguished by their long, prehensile tails, which they use, as monkeys and opossums do, for grasping and climbing. The very large family of the Octodontidæ has 17 Neotropical genera and four others are found in Africa. The Degu (_Octodon_) of Chili, Bolivia and Peru has the appearance of a large rat with tufted tail; the tuco-tucos (_Ctenomys_) are extremely abundant burrowers in Patagonia, where they honeycomb the ground over wide areas. The spiny rats (_Echimys_ and _Loncheres_) are so called from their appearance, not because they are related to the true rats; they have numerous horny spikes through the fur of the back. The Coypu (_Myocastor_) is a large, aquatic animal, remotely like the northern Muskrat, and the Hutias (_Capromys_ and _Plagiodontia_) are arboreal and found only in Cuba, Hayti and Jamaica. The chinchillas (_Chinchilla_ and _Lagidium_) of the Andes and the Vizcacha (_Viscaccia_) of the Argentine plains have somewhat the appearance of hares, but with long and bushy tails. The cavies, to which the familiar, misnamed Guinea-Pig (_Cavia porcellus_) belongs, are a very characteristic family; besides the true cavies, it includes the Patagonian Mara (_Dolichotis_), a large, long-legged, long-eared, short-tailed creature, and the Water-Hog, or Carpincho (_Hydrochærus_), an aquatic animal, as its name implies, and much the largest of existing rodents; it occurs in the warmer regions, south to Argentina. The heavy Paca (_Agouti_) and the slender-limbed Agouti (_Dasyprocta_) make up another family. Altogether, this assemblage of the porcupine-like suborder of rodents is a very remarkable one and in no other region of the earth is anything like it to be found. [Illustration: FIG. 106.—Hairy-rumped Agouti (_Dasyprocta prymnolopha_).—By permission of W. S. Berridge, London.] [Illustration: FIG. 107.—Three-toed Sloth (_Bradypus tridactylus_).—By permission of the N.Y. Zoölog. Soc.]