Armadilloes were one of groups of South American mammals managed to overcome isthmus of Panama and colonized North America successfully. In human epoch nine-banded armadillo (Dasypus novemcinctus) had moved far to the north, having overcome Mexican plateau, and had settled in southern extremities of North American prairies. In ice age armadilloes had been thrusted back far to the south, and along coast of gulf of Mexico only tiny relic populations of these animals remained. In such populations speciation and accumulation of new features passed roughly, and at the ending of ice age the southern part of North America had been inhabited with some species of armadilloes differing in shape and in habit of life. Some of them had died out subsequently, and others managed to fix in habitats for a long time, and their descendants make a part of Neocene fauna of North America. In tropical areas of North America where various freshwater reservoirs are present, one species of armadillos lives, which had mastered a habit of life unusual to these animals – the aquatic armadillo. This animal is about half meter long including tail. By its shape it differs from other armadilloes only a little – its body on back and sides is covered with armour divided to thoracal and lumbar shields. Between them some (usually 6 to 8) narrow belts lay, permitting a body of animal to be bent. The armour of this animal, however, is much thinner, rather than at ground species. Tail of aquatic armadillo is of oval outlines, short and wide. Head from above is covered with corneous plate. Bottom part of body is covered with thin rough wool. This animal has dark colouring – reddish-brown with lighter edges of thoracal and lumbar shields. Paws of aquatic armadillo are perfectly adapted to movement on fenny ground – between fingers and toes there are skin crosspieces increasing the support area and interfering with immersing of animal in marsh; also it helps in swimming. On forepaws strong claws are advanced. They are rather thinner, than at ground species which should dig firm deserted ground. With the help of claws aquatic armadillo digs from silt rhizomes and tubers of water plants making a part of its diet and also digs holes in riverbanks and among roots of trees. Ears of this animal are short and mobile. In the basis of ear there is a skin valve which closes ear duct when animal dives. Aquatic armadillo orientates itself under water freely with the help of sight – it has rather large eyes. But in muddy water it orientates itself and searches for a forage by means of touch: it also has mobile lengthened snout richly supplied with receptors. By means of snout it finds out food of animal origin – worms, crayfishes, snails and larvae of insects. Animal and vegetative food in its diet is present approximately fifty-fifty. Aquatic armadillo is active mainly in twilight, in the morning and in the evening. In hottest time of day it falls asleep in the hole dug out in a place where danger to be flooded at rising of water lavel to be minimal. This is very mobile animal able to run fast in underbrush or among thickets of reed in case of need. It is good swimmer due to the layer of hypodermic fat which serves as a float, and dives without any efforts due to rather big density. This armadillo can stay under water till about five minutes. Breeding of this mammal is not dated for the certain season – the posterity of this species may be observed in nature the year round, and the female can bring posterity up to two times for one year. After the pregnancy continuing about three months, the female gives rise to from four up to six cubs – they always are enzygotic twins. They are advanced well enough and at one week age they do not concede to adult individuals in swimming ability. Young animals can only dive no longer than for one minute. They remain with mother till about five weeks and then start to lead independent life. Because of too short intestines the young growth eats food of animal origin mainly. At the age of 16 months young animals become sexually mature; life expectancy is about 10 – 12 years.