POUCHED MAMMALS. 193 



edges, while generally the upper canines, if present at all, are small, and 

 the lower ones are absent. Among the cheek-teeth, the four pairs of 

 molar-teeth have broad, quadrangular crowns, generally surmounted either 

 by a pair of transverse ridges or by four blunt and rounded tubercles. 

 Such a type of dentition is adapted for a vegetable diet, which is charac- 

 teristic of the diprotodonts generally. 



From the allied families the kangaroo tribe are specially distinguished by 

 possessing rooted teeth, among which are three pairs of upper and one of 

 lower incisors, the upper incisors being nearly vertical, while the large lower 

 pair project nearly horizontally forwards, and in some cases are capable of 

 working against one another like the blades of a pair of scissors. A small 

 upper canine may or may not be present. The five-toed fore-limbs are in 

 general much shorter and weaker than the hinder pair, while the latter are 

 generally four-toed, and have the digit corresponding to the fourth of the 

 typical series of five greatly developed at the expense of the other three, 

 and forming the sole axis of support for the limb. Of the smaller toes, the 

 second and third, or those on the inner side of the enlarged digit, are enclosed 

 in a common skin, from which feature the hind-foot of this family is termed 

 syndactylous. The great relative size and strength of the hind-limbs of the 

 more typical members of the family is correlated with the upright position of 

 the body, and the mode of progression is by enormous leaps. In repose the 

 body is swung on a kind of pivot supported by the thigh-bones, the feet 

 resting on the ground, and the large and thick tail serving to form the third 

 leg of a tripod. Among the smaller forms the tail may be prehensile ; and 

 there are a few arboreal types in which the disproportion between the fore 

 and hind limbs is very much less strongly marked than is the case with the 

 typical kangaroos. All feed entirely on grass or leaves ; and the stomach, as 

 is so frequently the case with vegetable feeders, is of a somewhat complex 

 type. In the females the opening of the pouch is forwards, so that when it 

 contains young, these are in an upright position. The members of the 

 family are confined to Australia, Tasmania, and New Guinea, with some of 

 the neighbouring islands, such as the Aru group ; the true kangaroos, which 

 generally associate in large herd, or "mobs," and frequent either open 

 grassy plains or timbered districts, being the largest existing members of the 

 order. 



The true kangaroos and wallabies, constituting the genus Macropus, are 

 the typical representatives of a sub- family (Macropodinoe) characterised by 

 the sub-equality of the claws of the fore-feet, which are never very large, 

 and the generally elongated and pointed ears. In the dentition the last 

 upper pre-molar is placed either immediately in the line of the molars, or is 

 at most but slightly everted ; and the molars, which increase regularly in 

 size from the first to the fourth, are transversely ridged. As a rule, the 

 upper canine is either very small or wanting, and the central pair of upper 

 incisors are but slightly larger than the other two. From the other members 

 of the sub-family the numerous species contained in the genus Macropus 

 have the nose naked, the ears large, and the fur on the nape of the neck 

 nearly always directed downwards. The disproportion between the length 

 of the fore and hind limbs is very strongly marked ; and the large claw of 

 the hind-foot is always larger than the naked terminal pad on the sole of 

 the same. The tail is thick, tapering, and evenly haired throughout ; 

 and there are four teats in^the pouch of the females. There are upwards of 

 twenty-three species included in the genus, which may be arranged under 

 14 



