MACROPODIDJL 



163 



jaws always having large, simple, compressed crowns, with a nearly 

 straight or slightly concave free cutting edge, both outer and inner 

 surfaces usually marked by a series of parallel, vertical grooves and 

 ridges, these teeth being either set in the same line with the 

 molars, or slightly bent outwards. Molars with quadrate crowns, 

 having a blunt, conical cusp at each corner, the fourth notably 

 smaller than the third, sometimes rudimentary, and appearing early. 

 Fore feet narrow ; three middle toes considerably exceeding the 

 first and fifth in length ; their claws long, compressed, and but 

 slightly curved. Hind feet as in Macropus. Tail long and hairy, 

 sometimes partially prehensile, being used for carrying bundles of 

 grass with which these animals build their nests. 



The Potoroos or Rat Kangaroos are all small animals, none of 

 them exceeding a common rabbit in size. They inhabit Australia 

 and Tasmania, are nocturnal, and feed on the leaves of various 



pin- 



FIG. 54. Skull and Teeth of Rat Kangaroo (Bettongui lesueuiri). c, Upper canine. 

 The other letters as in Fig. 51. 



kinds of grasses and other plants, as well as roots and bulbs, which 

 they dig up with their fore paws. Nine species are known, present- 

 ing a considerable range of diversity in minor characters, and 

 admitting of being grouped in four principal sections, which may 

 be allowed the rank of genera. These are : 



Potorous. 1 Head long and slender. Auditory bullae some- 

 what inflated. Ridges on premolars few and perpendicular. 

 Large palatine foramina. Tarsus short. Muffle naked. Three 

 species, viz. P. tridadylus, P. gilberti, and P. platyops ; the last two 

 being confined to West Australia. 



Settongia. 2 Head comparatively short and broad. Ears short 

 and rounded. Auditory bullae generally much inflated. Large 

 palatine foramina. Tarsus long. Ridges on premolars numerous 



1 Desmarest, Nouv. Diet. d'Hist. Nat. ser. 1, vol. xxiv. Table Meth. p. 20 

 (1804). Syn. Hypsiprymnus, Illiger, Prodromus Syst. Mamm. p. 79 (1811). 

 - Gray, CharlcswortK s Mag. Nat. Hist. vol. i. p. 584 (1837). 



