Kangaroo, a marsupial animal, whose numerous species constitute the family macro-podidae, peculiar to Australia and the neighboring islands. (See Marsupials.) The dentition is as follows: incisors 6/2, canines none or one on each side in the upper jaw, premolars 1/1-1/1, molars 4/4-4/4; the upper incisors are large and broad, some of them resembling those of man, often arched, grooved, and dilated at the end; the lower incisors are horizontal, compressed, lanceolate, with cutting margins; the molars are broad, tuberculated, with nearly quadrangular crowns; in many of the species the lower incisors may be separated by means of the loose connection of the branches of the jaw at the chin. The head is elongated, the upper lip cleft, the muffle entirely or nearly naked, ears large, eyelashes springing directly from the lids; the clavicles weak and slender, especially in the large species; fore limbs usually very small in proportion to the hind; the hands naked beneath, with five well developed fingers, each armed with a strong curved claw; the hind legs large and powerful; the foot long, four-toed, the first or inner toe being absent, the second and third long, slender, and so united by integument as to resemble a single toe with a double nail; nails distinct and hollow beneath; fourth hind toe much developed, with a large solid claw, the fifth smaller with a strong claw; tail long, thick at the base, and usually very powerful; the marsupial pouch well developed and opening forward; mammae usually four; stomach complex, and caecum long and simple.

Kangaroos are vegetable feeders, browsing like ruminants, and like these, according to Owen, occasionally chew the cud; they vary in height from that of a man to that of a hare, but when browsing apply the fore feet to the ground; at other times they rest upon the tripod formed by the hind legs and powerful tail, with the fore part of the body inclining slightly forward. They are the only marsupials which are not of nocturnal habits. - Of the 30 species described, the largest and the best known is the great kangaroo (macropus giganteus, Shaw), discovered in 1770 on the coast of New South Wales during Cook's first voyage; an adult male in the British museum measures 5 1/4 ft. from tip of nose to root of tail, the latter being 3 1/2 ft. additional, the head 8 1/3 in. to the ears, ears about 5 in., length of forearm and hand (without the claws) 17 in., and of tarsus alone 15 1/2 in.; the female is about one third smaller. The hair is moderately long and soft, of a general gray brown above and paler below, toes and end of tail black. It prefers low grassy hills and plains and open districts, where it browses upon the herbage and low bushes, retiring from the heat of midday under the shelter of the ferns and tall grasses.

At the least alarm it raises itself on the hind legs and tail, its height enabling it to command a very extensive view; exceedingly timid, with acute senses of smell and sight, it is difficult to approach, but occasionally falls a victim to the spears and traps of the natives who hunt it for food; the English colonists pursue it so successfully with hound and gun that it is now rarely seen except in the interior. The kangaroo sometimes turns upon his canine enemies, and will either rip them open with the sharp hind feet, or clasping one in his fore paws leap to some water hole and drown it; the unwary human hunter may meet a similar fate. One of the principal uses of the peculiar Australian weapon, the boomerang, which may be made to fall in advance of or behind the thrower, is to destroy the timid and wary kangaroo. Though nearly as awkward as a bat when browsing, it is a most fleet and graceful animal when making its enormous bounds, sometimes clearing a rod at a leap. The fore feet are prehensile, and are used in the various offices connected with the care of the young. Kangaroos are not generally gregarious. The skin is valuable for leather, which is esteemed for shoes and gloves; the flesh is also considered a delicacy.

Prof. Owen has ascertained that the gestation in the M. giganteus is 29 days; the young when first born resemble, according to observations made at the London zoological gardens by him, earth worms in color and semi-transparency, the body being bent upon itself, the short tail tucked in between the hind legs, and these last one third shorter than the fore legs; the whole length, when stretched out, was 1) in. As soon as born, the young are placed in the mother's pouch, which is held open by her fore paws while they are taken up by her mouth. There is no vascular connection between the young kangaroo and the nipple; when separated by force the milky secretion is seen oozing out; the young seem unable to regain the nipple, which is sometimes replaced in the mouth by the mother; the teat has a circular enlargement at the tip, which makes it easy to be retained. Though the young can firmly grasp the nipple by the lips, it cannot draw the milk without the aid of the mother, which by the action of a muscle in the mammary gland can inject this fluid into the mouth of the suckling; lest the act of injection, when not coinciding with that of suction, should endanger the life of the foetus from suffocation, the cartilages of the larynx are so arranged that the opening of the glottis is placed at the top of a cone which projects, as in whales, into the posterior nostrils, so that the stream of milk passes on each side into the gullet without the possibility of entering the windpipe. - The subgenus lagorchestes (Gould) includes a few small kangaroos with the muffle clothed with velvet-like hairs; halmaturus (F. Cuv.) comprises those in which the muffle is naked in front; heteropus (Jourdan) contains the rock kangaroos, with compact body, hind feet comparatively short and rough beneath, hairy tail, and naked muffle.

In the tree kangaroos (dendrolagus, Muller) the fore legs are almost as long and strong as the hind legs, with pointed claws, and the tail is long, bushy, and cylindrical; they ascend trees with facility. The rat kangaroos constitute the genus hypsi-prymnus (Illiger), called also potoroos; they are about the size of a rabbit, with upper canines, compact body less elongated anteriorly, and with the toes of the fore feet unevenly developed, the three central ones the longest, with solid nails compressed and broadest above; they feed on roots which they dig up with their fore paws. - Fossil kangaroos have been found in the limestone caverns and alluvial deposits of Australia, of which the M. Atlas, Titan, and Goliah (all of Owen) were at least one third larger than any living species. The fossil genera dlprotodon and nototherium of Owen, the former superior and the latter equal to the rhinoceros in bulk, found in the alluvial deposits of the Australian Condamine river, are considered to have been marsupials coming near the kangaroos and the wombats.

Great Kangaroo (Macropus giganteus).