IIROWS TREK KANGAROO. 
191 
(sometimes as long os the anterior two true molars taken 
together), compressed, and presenting a cutting edge, the 
outer and inuer surfaces with small vertical grooves; the 
true molars successively decreasing in size from the foremost 
to the hindermost; their crowns nearly square, and divided 
hy a transverse and a longitudinal groove into four blunt 
tubercles; auditory bulke large, and as it were inflated; 
zygomatic arch with a small vertical diameter: toes of the 
fore feet armed with very long, compressed, ami hut slightly 
curved solid claws; the two lateral toes much shorter than 
the others, and with the claws small in proportion. 
'Whilst the oesophagus terminates in the middle division of the 
stomach in the true Kangaroos, in the Hat-Kangaroos (Prof. 
Owen states) it is removed from the commencement of the 
middle sacculated compartment to its termination 1 . The 
caecum is much shorter than in the great Kangaroos. 
The Rat-Kangaroo, or Potoroos, are all of small size, os 
compared with most other species of the Kangaroo family, 
being, for the most part, about equal in bulk to the Common 
Hare or Rabbit. Their body is of a more compact form, the 
fore parts being less elongated; and the cars being small and 
rounded, gives them a different aspect, when compared with 
the typical Kangaroos; but some of the smaller species of 
Macropus could not be distinguished from the Rat-Kangaroos 
in these respects. In oxternal characters, one of the most 
striking points of distinction is in the structure of the fore 
foot, the toes being more unevenly developed in the Rat- 
1 Todd’s Cycloptedia of Anatomy, &c. iii. p. 301. «• The stomach is as 
singularly complicated as in the Kangaroos, and the complication is essentially 
the same in both, arising from the sacculation of the pnrictes of a very long 
canal, by a partial disposition of shorter bands of longitudinal fibres ; but in 
the Hypsiprymni this sacculation is confined to that part of the stomach which 
lies to the left of the oesophagus, while the right division of the cavity has the 
ordinary form and structure of the pyloric moiety of n simple stomach. The 
left cardiac division is enormously developed; in relative proportion, indeed, 
it is surpassed only by the true ruminant stomachs.”—Owen, loc. cit. 
