22 CLASS MAMMALIA. 



low it, are connected by the skin as far as the last phalanx. 

 The toes of the fore-feet differ little from those of the com- 

 mon Carnassiers, while in the Koala these same toes are 

 divided into two groups for the act of seizing; the thumb 

 and index being on one side, and the three others on the 

 opposite. The four hinder toes are connected two by two, 

 and very distinct from the thumb. In the Dasyuri, which 

 run upon the ground like the Martens, the fore-feet have 

 five toes, and the hinder four, all separated and armed with 

 curved claws, while the hinder thumb is but a simple 

 tubercle. Finally, the Didelphes which climb trees have 

 toes like the Dasyuri, except that the posterior thumb is 

 distinct, and without a nail like that of the Phalangers. 

 The Chironectes which swim differ from the Didelphis, 

 only in having the hinder feet palmate. 



There is no tail in the Phascolomys. In the Koalas it is 

 a simple tubercle, but considerably long in all the other 

 genera. In the Didelphes, the Chironectes, and the true 

 Phalangers, it is naked, scaly, and prehensile. In the 

 Kanguroosand Potoroos, it is strong, triangular, and conic, 

 and concurs to locomotion with the long hinder limbs. 

 The Isoodonta and the Perameles have it of the same form, 

 but much less robust. Finally, the Dasyuri, and par- 

 ticularly the flying Phalangers, have it much elongated, 

 and more or less tufted. 



In the Petauristae alone, we find the skin of the sides 

 extended between the fore and hind legs, serving as a 

 parachute after the manner of the Galeopitheci and Po!a- 

 touches. 



The Crab-eating Didelphis, the Kanguroo, the Perameles, 

 the Isoodon, the Potoroo, the Phalangers, the Petauristae, 

 and the Phascolomys alone, have the ventral pouch which 

 has given a denomination to the entire tribe. In the rest 

 the mammae are visible without, and some have on each 

 side the fold of skin which forms the pouch, but scarcely 



