748 MAMMALIA. 
second and third toes are narrow and bound together by skin, 
the fourth and fifth free. The tail is generally long and pre- 
hensile. The stomach is simple, the caecum usually large. 
Average dental formula, 23: 34, 
Ty 0, 0-2, 3-4 
Examples.—The grey Cuscus (Phalanger orientalis); Tarsipes, a 
small mouse-like animal which feeds on honey, and is remark- 
able in having no inflection of the angle of the mandible and 
no cecum ; the flying phalangers (Pefaurus), with a parachute 
of skin extending from the little finger to the ankle ; the Koala, 
or ‘‘native bear” (Phascolarctos cin- 
ereus), a relatively large form, about 
2 ft. in length. An extinct form, 
Thylacoleo, of the late Tertiary period 
of Australia, is interesting in its extra- 
ordinary dentition, the functional teeth 
being reduced to large front incisors and 
the third premolars, both adapted for 
sharp cutting. 
4. Family Macropodidee. — Kangaroos, herbi- 
vorous terrestrial Marsupials. Denti- 
tion, 222274, 
7 1, 0, 2 4 
and suited for cropping herbage. The 
hind-legs are usually larger than the 
fore-legs, and the animals move by leaps. 
Examples. — The true kangaroos, ¢.g. 
Macrogus ; the rat-kangaroos or potoroos 
(Potorous) ; the genus Hypsiprymnodon, 
with a foot approaching that of the 
Phalangers. 
The incisors are sharp, 
Fic. 405.—Foot of The true kangaroos, belonging to the genus 
young kangaroo. = Afacropus, include the largest living Marsupials ; 
2, 3, Small syndactylous but within the genus there is much difference in 
toes; 4, large fourth sjze, 
toe; 5, fifth toe. The grey kangaroo (JZ. giganteus) lives on 
the grassy plains of Eastern Australia and 
Tasmania, and is as tall as a man ; the Wallabies, at home in the bush, 
are smaller, and some are no bigger than rabbits, 
The hind-limbs seem disproportionately long, and are well suited for 
rapid bounding, The long tail, carried horizontally, helps to balance 
the stooping body as the animal leaps, and it gives additional stability 
to the erect pose. The fore-limbs sometimes come to the ground when 
the animal is feeding, and in the largest species they are strong enough 
to throttle a man. 
The fore-limbs bear five clawed digits; the hind-feet have only four. 
The hallux is absent; the fourth toe is very long; the fifth is about 
half as large ; the third and second are too slender to be useful for 
more than scratching, and are bound together by the skin (syndactylous). 
The length of the hind-limb is due to the tibia and fibula, and to the 
