504 



CHORD AT A. 



jumping. At rest the kangaroo places the whole foot on the ground. 

 All are strictly herbivorous and the stomach is complex, the front part 

 being sacculated and containing the oesophageal and cardiac glands. The 

 true kangaroos and wallabies are cursorial, playing the part of antelopes 

 or deer in the districts they frequent. The rat-kangaroos are smaller, 

 nocturnal and partially fossorial. Others, the tree-kangaroos, are 

 arboreal. 



Family II. — Phalangeridae. — A family containing a great number 

 of small arboreal animals. They are usually woolly and often have a 

 prehensile tail. In addition, a number of them have a flap of skin or 

 patagium which enables them to "sail" from tree to tree (incidental 

 serial). From these habits it is not surprising to find five toes all 

 present on each limb and the hallux opposable to the other four. 

 These phalangers approach more nearly the Polyprotodontia^ especially 

 as they have additional small functionless incisors in the lower jaw, and 

 their diet is by no means strictly herbivorous. The common koala 

 {Phascolarctos) and the flying squirrels {Petaurus) should be noted. 



Family III. — Phascolomyidae. — A very small family, consisting 

 of about three species of wombats. The wombat {Phascoloviys) is a 

 small bear-like terrestrial or partially fossorial animal. All five digits 

 are retained on both limbs and the syndactylism is not very pronounced. 

 But the peculiar dentition is the great feature of this form. Just as 

 similar external conditions cause a resemblance of the Tasmanian wolf 

 ( Thylacimis ) to the dog, or A'otoryctes to a mole, so here we have a 

 metatherian repetition of the eutherian rodent. There is one pair of 



incisors in each jaw ; they grow 



Fig. 349. —Posterior View of from persistent pulps and have 



Lower Taw of Wombat. ^"^^^^^ o^^y ^^ ^^9 ^^^^^ s|nface. 



There are no canmes and there 

 is a large space or diastema 

 between the incisors and the 

 "cheek-teeth." These are five 

 in number, one premolar and 



four molars: ^^ is the formula. 

 1014 



Family IV. — Epanorthidse. 



— Another small family which 

 contains a remarkable little ani- 

 mal, the selva or opossum-rat 

 {Ccenolestes). The selvas have 

 recently been found alive in S. 

 America though they were supposed to be extinct. They are dipro- 

 todont in their lower jaw, but the teeth of the upper jaw more nearly 

 resemble certain of the Polyprotodontia. They difl"er from the rest of the 

 Diprotodontia in not having a syndactylous foot, though doubtful traces 

 of syndactylism in some of their fossil allies have been stated to exist. 



Distribution of Diprotodontia. — The families of the 

 kangaroos, phalangers and wombats, in fact nearly all the 



Showing inflected angle. 



