76 LLOYD'S NATURAL HISTORY. 
definition of the two is by no means easy. The following are, 
however, the distinctive characters which serve to differentiate 
the members of the present family as a whole from those of 
the JMJacropodide :— 
All the feet with five toes; those of the fore limbs generally 
sub-equal ; those of the hind limbs, with the second and third 
united in a common integument (syndactylous), the fourth the 
longest of the series ; the fifth but little smaller, and the first 
(or hallux) large, furnished with a broad clawless terminal pad, 
and widely opposable to the others (see fig. 3, p. 12). Tail 
(except in Phascolarctus, where it is rudimental), long, and 
nearly always prehensile. Stomach simple ; intestine, except in 
Tarsipes, furnished with a blind appendage or cecum ; and 
the pouch well-developed, with its aperture directed backwards. 
In the skull the lower jaw lacks the large pocket-like cavity on 
the outer side of the hinder part, and communicating with the 
canal of the dental nerve, which forms so characteristic a feature 
in the Macropodide. Owing to the frequent presence of a 
variable number of functionless minute teeth in the anterior 
part of the jaws, the dentition as a whole is too variable to admit 
of precise formulation. There are, however, generally three pairs 
of upper and one pair of functional lower incisors ; the latter | 
wanting the scissor-like action characterising the Macropodida. | 
Of the two or three premolars usually present, the last is | 
generally furnished with a sharp cutting edge (although this | 
character is less marked than in the preceding family), and is | 
placed obliquely to the line of the molars. The molars, ] 
generally four in number, may be crowned either with blunt | 
tubercles or with sharp-cutting crests. ! 
It will be obvious that almost the only characters which | 
separate the Phalangeride from the Musk-Kangaroo are the | 
structure of the lower jaw and the backward direction of the | 
aperture of the pouch. | 
Bik 
