. The naturalist in La Plata. er. As these pointsof affinity are believed to be real and not merely adaptive, theymust be due in accordance with our view to inheritance from acommon progenitor. Therefore we must suppose either that allrodents, including the vizcacha, branched off from some ancientmarsupial, which will naturally have been more or less inter-mediate in character with respect to all existing marsupials; or,that both rodents and marsupials branched off from a commonprogenitor. . On either view we must suppose that thevizcacha has retained, by inheritance, more of the characters of
. The naturalist in La Plata. er. As these pointsof affinity are believed to be real and not merely adaptive, theymust be due in accordance with our view to inheritance from acommon progenitor. Therefore we must suppose either that allrodents, including the vizcacha, branched off from some ancientmarsupial, which will naturally have been more or less inter-mediate in character with respect to all existing marsupials; or,that both rodents and marsupials branched off from a commonprogenitor. . On either view we must suppose that thevizcacha has retained, by inheritance, more of the characters ofits ancient progenitor than have other rodents.—Darwin ; Originof Species. 290 The Naturalist in La Plata. landowners, which has been more fortunate in itsresults—or unfortunate if ones sympathies are withthe vizcacha—than the war of tne Australiansagainst their imported rodent—the smaller andmore prolific rabbit. The vizcachas on the pampas of Buenos Ayreslive in societies, usually numbering twenty or thirty ^-%1. Vizcachas. members. The village, which is called Vizcachera, iscomposed of a dozen or fifteen burrows or mouths ;for one entrance often serves for two or more distinctholes. Often, where the ground is soft, there aretwenty or thirty or more burrows in an old vizca-chera; but on stony, or tosca soil even an oldone may have no more than four or five are deep wide-mouthed holes, placed veryclose together, the entire village covering an area Biography of the Vizcacha. 291 of from one hundred to two hundred square feet ofground. The burrows vary greatly in extent; and usuallyin a vizcachera there are several that, at a distanceof from four to six feet from the entrance, open intolarge circular chambers. From these chambersother burrows diverge in all directions, some run-ning horizontally, others obliquely downwards to amaximum depth of six feet from the surface : someof these burrows or galleries communicate withthose of other burrows. A vast amount
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