4i8 



THE POPULAR SCIENCE MONTHLY. 



wenera 



2. Dorcojysis, with a very large first back tooth. 3. The tree 

 kangaroos {Dendrolagus), which frequent the more horizontal branches 

 of trees, have the fore-limbs but little shorter than the hind-limbs, 

 and inhabit New Guinea ; 4. The rat-kangaroos {HypsiprymniLs)^ 

 which have the first upper grinding-tooth large, compressed, and with 

 vertical grooves. 



Fig. 6. Skdll of a Eat-Kaugaeoo (Ilypsiprymnus). 



These four genera together constitute the kangaroo's family, the 

 3facropodkloB, the species of which all inhabit Australia and the 

 islands adjacent, but are found nowhere else in the world. 



The species agree in having 



1. The second and third toes slender and united in a common fold 

 of skin. 



2. The hind-limbs longer than the fore-limbs. 



3. No inner metatarsal bone. 



4. All the toes of each fore-foot provided with claws. 



5. Total number of incisors only |. 



These five characters are common to the group, and do not co- 

 exist in any other animals. They form, therefore, the distinguishing 

 CHAEACTEES of the kaugaroo's family. This family, Macro2:>odidce^ is 

 one of the six other families which, together with it, make up that 

 much larger group, the kangaroo's oedee. As was just said, to un- 

 derstand what a kangaroo is, we must know " what are the relations 

 borne hj h.\^ family to the other families of its order;" and accord- 

 ingly it is needful for our purpose to take at least a cursory view of 

 those other families. 



There is a small animal, called a bandicoot (Fig. 7), which, in ex- 

 ternal appearance, differs very plainly from the kangaroo, but resem- 

 bles it in having the hind-limbs longer than the fore-limbs, and also 

 in the form of its hind-feet, which present a kangaroo structure, but 

 not carried out to such an extreme degree as in the kangaroo, and 

 therefore approximating more to the normal type of foot, there being 

 a rudimentary inner toe and a less preponderant fourth toe ; the sec- 

 ond and third toes, however, are still very small, and bound together 

 by skin down to the nails. In the fore-foot, on the contrary, there is 

 a deficiency, the outer toes being nailless or Avanting. The cutting- 

 teeth are more numerous, these being I -^. 



This little creature is an example of others, forming tlie family 



