BETTONGIA. 41 
Genus IV. BETTONGIA, Gray (1837). 
Rhinarium wholly naked. Ear very short and rounded. Fore 
claws long and strong. Hind feet longer than the head, the soles 
naked and coarsely granulated. Tail more or less prehensile, 
thickly hairy, with a more or less distinct crest. 
<4 L328 4 2 0.0.3.4 Vad eae 
Dentiiion.—I. 7, ©. P- opgp M- oaa X 2= 34. 
Habits.—Terrestrial; herbivorous. 
Note.—It occasionally happens that a fifth molar is present 
either in one or both rami of the upper jaw, or even in both rami 
of both jaws, so that, as Mr. Oldfield Thomas remarks, while 
having the comparatively highly specialized characters of the 
other members of the family, this genus presents the remarkable 
condition of retaining such an ancient and generalized character 
as the possession of more than four molars. On the other hand 
the fourth molar is often aborted. The members of this genus 
alone among terrestrial mammals possess prehensile tails, which 
they use for carrying grass, sticks, &c., these being firmly held by 
the tail being twisted downwards upon them. The four species 
are very similar to each other externally, so much so that no 
reliance can be placed on any determination which does not rest 
upon an examination of the cranial and dental characters. 
1. BEYTONGIA LESUEURI, Quoy & Gaimard, sp. (1824). 
Lesueur’s Rat-Kangaroo. 
Fur soft, close, and thick. General color above grizzled gray ; 
below white ; sometimes an indistinct white hip-mark. Arms 
and legs white ; hands and feet white or pale brown ; hairs of the 
latter long and bristly, nearly covering the claws. Tail colored 
above like the back, the upper hairs not forming a distinct crest ; 
below pale brown or white ; the tip white. 
Dimensions.—Head and body about eighteen inches; tail about 
twelve inches, 
Habitat.—South and West Australia. 
References.—Thomas, B.M. Catal. p. 112, pls. xiii. figs. 6 and 7 
(teeth), xiv. fig. 7 (nasals), 8 (bulla); Gould, Mamm. Austr. ii. 
pl. Ixiv. 
2. Brerroneia cunicuLus, W. Ogilby, sp. (1838). 
Tasmanian Rat-Kangaroo. 
Fur and general color as in B. leswewri, but without trace of 
hip-mark. Arms, legs, hands, and feet white ; hairs of latter as 
in B. lesweurt. Tail above as in B. lesueuwri, except that towards 
the end it occasionally becomes dark brown or black ; below dirty 
white ; tip sometimes white all round. 
