to a separate family which will include but the one species, D. branickii.
Fam. 6. Chinchillidae.—This family, likewise South American, contains three genera,[[357]] all of which agree in having long limbs, especially the hind-limbs, and a bushy and well-developed tail. The hair is exceedingly soft, hence the commercial value of "chinchilla."
The genus Chinchilla, containing but a single species, C. laniger, is a small and squirrel-like creature, living at considerable heights in the Andes. The eyes, as it is a nocturnal creature, are naturally large; and so also are the ears. The fore-feet have five toes, the hind-feet only four; they are furnished with feeble nails. The innermost toe of the hind-foot has a flat and nail-like claw. There are thirteen dorsal vertebrae, and the long tail has more than twenty. The clavicle is well developed, as in the other genera of this family. The large intestine of this animal is extraordinarily long; the proportions of the different regions of the gut are shown by the following measurements: small intestine, 820 mm.; caecum, 125 mm.; large intestine, 1340 mm. Such a disproportion between the large intestine and the small, to the advantage of the former, is a very strange fact in the anatomy of this Rodent.
The genus Lagidium (also called Lagotis), which includes "Cuvier's Chinchilla," is also a mountain dweller. There are several species of this genus, which differs from Chinchilla by the complete abortion of the thumb and of the great toe. The intestinal proportions are those of Chinchilla. The ears and tail are long. L. cuvieri measures 1½ feet in length.
Lagostomus, again, has but one species, L. trichodactylus. The animal has a tail about half the length of the body. The digits are reduced as compared with Chinchilla, there being but four on the fore- and three on the hind-feet. There are only twelve dorsal vertebrae, and seven ribs reach the sternum. In the skull a distinguishing mark from the last two genera is the separation of the infra-orbital foramen into two by a thin lamella of bone. The large intestine is between one-half and one-third the length of the small intestine, and thus differs much from that of Chinchilla.
Fig. 243.—Vizcacha. Lagostomus trichodactylus. × 1⁄10.
The Vizcacha lives in societies of twenty to thirty members,[[358]] in a "village" ("Vizcachera"), a dozen or so of burrows, which intercommunicate. They lie at home during the day and come out in the evening. Their burrows, like those of the Prairie Marmot, harbour other creatures, which apparently live on amicable terms with the Vizcachas; such are the burrowing owl, a small swallow, and a Geositta. The Fox also affects these burrows, but then he ejects the rightful owner of the particular burrow which he selects. When the young Foxes are born the vixen hunts the Vizcachas for food. The Vizcacha has a most varied voice, producing "guttural, sighing, shrill, and deep tones," and Mr. Hudson doubts if there is "any other four-footed beast so loquacious or with a dialect so extensive." These animals are very friendly, and pay visits from village to village; they will attempt to rescue their friends if attacked by a Weasel or a Peccary, and to disinter those covered up in their burrows by man.
Fam. 7. Cercolabidae.—A number of the characters which differentiate this family from the Hystricidae or Ground Porcupines of the Old World are given under the description of the latter. The principal external characters are the prehensile tail, the admixture of spines with hairs, and the nature of the sole of the foot. In these points the New-World Cercolabidae differ from the Old-World Hystricidae. It is interesting to notice that