ON THE EXTINCT ANIMALS OF THE COLONIES OF GREAT BRITAIN. 267 
not anticipating in 1836 to find it but a middle-sized species. 
Subsequently I received evidences of a kangaroo with a skull of 
12 in. long; and next, of one with a skull as large as that of a 
full-sized ox, 16 in. in length. 
Now, these extinct species do not differ merely in magnitude 
from each other, and from the smaller existing kinds, but in 
modifications of the teeth and in the proportions of the limbs. 
As the kangaroos gained in bulk they lost in power of leaping. 
The hind limbs were less disproportionately long, the fore limbs 
less disproportionately short. Both pairs took a more equal 
share in the support and progression of their bulky frames. 
Nevertheless, all the well-marked characteristics of the macro- 
podal foot were retained, the modifications being restricted to 
those of size and proportion of toes and leg-bones. 
So likewise with the teeth. Certain teeth of extinct kinds 
were shaped for cutting, the same teeth in other kinds for 
pounding. 
Species not exceeding or inferior in size to existing kangaroos 
manifested specific distinctions in the teeth, in the skull, and in 
parts of the skeleton. I have had to name and characterize a 
score of kinds of kangaroo that have existed in Australia and 
have passed away ; and these extinct species have made known 
to the zoologist seven generic modifications of the macropodal 
family, distinct from any of the genera still represented by 
known living kinds of kangaroo. 
The most interesting result of these comparisons of the fossil 
remains of kangaroos were the indications of a gradual resump- 
tion of the more ordinary quadrupedal character in the larger 
extinct species. This transition I found to be completed in 
still larger forms which retained, in the main, the macropodal 
type of dentition, the modifications of the teeth indicating a 
more strictly herbivorous character of quadruped. 
The first of these forms was manifested under three specific 
modifications, on which have been founded a Nototherium 
Mitchelli , a Not . Victorice , and a Not . inerme. Of this genus 
I have as yet, indeed, obtained little more than portions of 
the skull and teeth. But a few detached bones of the ankle 
show a deviation from the kangaroo type of foot toward that of 
the ordinary character, and an arm-bone indicates a more equal 
size with stouter proportions of the fore and hind limbs. I 
infer the Nototherium to have resembled in general character a 
large tapir, but it was essentially a marsupial quadruped.* 
Amongst the cave-fossils submitted to me in 1835 by Sir 
* An entire skull of the Nototherium has been discovered. It is now in 
the Museum of Natural History at Sydney, the Trustees of which have 
transmitted a cast to the British Museum. 
