PHALANGE R FAMILY. 
257 
same fts in the Rat-Kangaroos; and, indeed, the structure of 
the teeth does not differ much. 
The anterior upper pair of incisors (as in thellypsiprymni) 
are larger and longer than the rest: the largo lower incisors 
are nearly horizontal, or directed obliquely upwards. The 
canine, though hy no means large, is usually rather more 
developed than in the Rat-Kangaroos; the promolar, which 
is contiguous with the true molars, is shorter and broader 
than in the animals just mentioned, and the true molars 
have the four principal cusps more developed. 
The family may be divided into three principal sections or 
genera, readily distinguished by obvious external characters. 
As approaching in certain characters most nearly to the 
Wombats, we will commence with die genus Pliascolarctus V, 
the only known species of which (the Koala) is distinguished 
from other Phalangers by the absence of a tail: next follows 
1 With regard to the position of the Wombat, and the Koala ( Phascolarctus) 
in a natural system, I may observe, in the first place, theWornbat, cater is paribus , 
shows some affinity to the Phalangistida in the possession of a thumb, which, 
though short, is very broad, and sufficiently distinct; then beyond this wc 
have to add, that the limbs are equal, the tibia and fibula are widely sepa¬ 
rated, excepting, of course, at the extremities ; and the stomach U simple, as 
in the Phalanger group. On the other hand, wc perceive in the Koala an 
animal possessing all the essential characters of Phalangista, but in which the 
stomach is provided with a peculiar glandular apparatus, und the tail is want¬ 
ing, asm the Wombat. The two animals, moreover, agree very closely in the 
structure of the humerus ; they agree in the non-possession of a patella, in the 
absence of ligamentam teres, and in the outermost of the articular surfaces of 
the upper extremity of Uie tibia being continuous with the articular surface of 
the fibula. The skull of the Koala, as compared with that of a typical 
Phalangista , differs in having the posterior palatine openings confined to the 
palatine bone, which is also the case in the Wombat : the lower jaw differs in 
the greater extent of the symphysis ntenti ; and lastly, an approximation to 
that Rodent-like type of dentition which is exhibited by the Wombat, is per¬ 
ceptible in the Koala, in the smaller development of the posterior incisors 
and canines of the upper jaw, and the total absence of any of those premolars 
which, in the typical Phalangers, intervene between the canine and the five 
VOL. I. 
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