172 THE KANGAROOS. 



The Hypsiprymnii oi' Potoroos^ and Kangaroo-rats 

 as they are termed, differ chiefly from the true Kan- 

 garoos, in possessing distinct canines ; the foremost 

 pair of incisors, in the upper jaw, are larger and con- 

 siderably longer than the others, which are propor- 

 tionately smaller than in the Kangaroos, and have no 

 external grooves ; the incisors of the lower jaw are 

 narrower and not dilated in the middle, but gradually 

 increase in width from the point towards the base. 

 The canines are rather small, compressed, and but 

 slightly pointed. The false molars are proportionately 

 larger than in the Kangaroos, and generally have 

 numerous distinct vertical grooves both on the outer 

 and inner side. The true molars before worn, present 

 each four blunt tubercles : the foremost of these 

 molars is the largest, and the hindermost the small- 

 est. This decrease in the size of the posterior molars 

 I have never observed in any of the true Kangaroos. 

 The skull is less suddenly contracted in front of the 

 orbits, and broader between the orbits. The toes of 

 the fore-feet are less evenly developed, and the claws 

 are longer and fitted for burrowing. The anterior 

 extremities are in general proportionately longer, the 

 hinder limbs, as well as the tail, are less powerful^ 

 and the toes and claws are less robust. 



