belonging to the Order Rodentia. 129 
case of the Conilurus, and, therefore, cannot be justly compared to the sin- 
gular structures erected by that animal. I regret my inability to afford any 
farther information upon this interesting subject; but however imperfect the 
description which I am at present able to give, it will at least serve to direct 
the attention of future inquirers towards an animal, no less remarkable for 
the apparent singularity of its external characters, than for its interesting 
habits, and the geographical position which it occupies, in common with 
some of the most anomalous forms of the animal kingdom. From the ex- 
treme rarity of this animal in European Museums, as well as from its being 
unknown to all gentlemen connected with the colony of New South Wales 
of whom I have inquired concerning it, it must have disappeared from the 
inhabited parts of the country; and, indeed, it may be easily imagined that 
a creature of such peculiar habits, would necessarily retire before the ad- 
vance of population, more rapidly than ordinary quadrupeds. 
Genus Dipus. 
The discovery of a true Jerboa on the central downs of Australia, is an event 
of no small interest to the Scientific Zoologist, who occupies himself with the 
important question of the Geographical distribution of animals. "The arid 
deserts of Asia and Africa, the solitary steppes of Southern Siberia, and the 
boundless prairies of America, have been long known to be inhabited by 
numerous species belonging to this or the closely allied genus of Gerbilles ; 
in short, wherever extensive and open plains were found to exist, whether in 
the Old World or in the New, there likewise were found these little two-legged 
rats, hopping along or running with great velocity upon their hind legs, and 
appearing as if nature had expressly intended them to occupy such a situa- 
tion. Australia alone was believed to form an exception to the general rule, 
in this instance as in so many others: who will undertake to say that the 
progress of discovery may not destroy its anomalous character in many other 
instances, as it has done in this? 
For the interesting discovery in question we are entirely indebted to Major 
Mitchell; and I think it only due to the enterprise and ability of that merito- 
rious officer, whose successful researches in the interior of Continental 
Australia have had the rare merit of enlarging the bounds of science, and at 
VOL, XVIII. E 
