VISCACHA, or  ,BISCACHA, a large South American burrowing rodent mammal belonging to the family Chinchillidae and commonly known as Lagostomus trichodactylus, although some writers prefer the name Viscacia . With the cheek-teeth formed of a number of parallel plates in the manner characteristic of the family, the viscacha is distinguished from the other members of that group by having only three hind toes; while it is also the heaviest-built and largest member of the group, with smaller ears than the rest . It has a long tail and shaggy fur; the general colour of the latter being dark grey, with conspicuous black and white markings on the face . Viscachas inhabit the South American pampas between the Uruguay river and the Rio Negro in Patagonia, where they dwell in warrens covering from too to 200 sq. ft. and forming mounds penetrated by numerous burrows . The ground around the " viscachera " is cleared from vegetation, the refuse of which is heaped upon the mound . Anything the rodents may meet with on their journeys, such as thistle-stalks or bones, are collected and deposited on the viscachera . Deep down in the burrows dwell the viscachas, from which in frequented districts they seldom emerge till evening, unless to drink after a shower . Their chief food is grass and seeds, but they also consume roots . When alarmed, they rush to their burrows, and if these are disturbed utter a growling sound . A pair of prairie burrowing owls (Speotyto) are almost invariably inhabit-ants of a viscachera (see RODENTIA) . (R .