BRUSII-TAILEI) ROCK-KANGAROO. 
107 
body when perched in situations which require it, but is of 
little assistance in supporting the weight of the trunk. The 
muffle is naked, as in the scrub-inhabiting Kangaroos. 
In the skull in the Rock-Kangaroos, the muzzle and nasal 
bones are narrow, and the zygomatic arches are more pro¬ 
minent than usual; but in theso respects the skull in the 
Rock-Kangaroos greatly resembles that of M. Icporuulv* 
figured in Plato 5, fig. 17; that skull, however, when viewed 
from beneath, presents a rare exception among the Macropus 
group, in having the auditor)* chamber expanded, and enclosed 
externally hv a thin and nearly spherical bony plate; a 
character in which it approaches the skulls of the Rat- 
Kangaroo group, hut which is not found in the Heteropus 
section. The angle of the lower jaw is less raised than iu 
most other Kangaroos. The two posterior upper incisor teeth 
are rather small; the last presents a deep notch in the crown 
(see Plate 5, fig. 10). 
MACROPUS (. Heteropus) PENICILLATUS. 
Brush-tailed Rock-Kangaroo. 
( Plate 1.) 
Macropux pniieillatus. Gray, in Griff. Ann. Kingdom, v. p. 527. 
Petroyale pcnicillata. Gray, Magazine of Nut. Hist, for November 1837. 
Vol. 1. (New Series), p. 583. 
14 44 Gould, Monogr. of tbc Macropodidw, Part 2, 
eighth Plate. 
(?) Hcteroptu alboyulari$. Jourdan, Comptcs Remlus, &c. for October 1S37* 
p. 552; and Annales dcs Sciences Naturelles for 
December 1837, tom. viii. p. 368. 
Fur long ; general colour deep purplish grey ; chin, mesial line of 
throat, and chest, white ; sides of body sooty brown, almost 
black immediately behind the fore leg ; abdomen brown or 
yellowish ; muzzle and occiput dusky; chcck-mark greyish 
