THE NATURAL HISTORY OF THE KANGAROO. 
393 
indicated in geological language as the Mesozoic period — the 
middle of the secondary rocks. 
But Australia presents us with a yet more interesting case of 
64 survival.” Certain fish-teeth had from time to time been 
found in deposits of oolitic and triassic date, and the unknown 
creature to which they once belonged had received the name of 
Cercttodus. Only five years ago this animal, supposed to have 
been extinct for untold ages, was found still living in Queens- 
land, where it goes by the name of 44 flat head.” It is a fish of 
somewhat amphibious habits, as at night it leaves the brackish 
streams it inhabits, and wanders amongst the reeds and rushes 
of the adjacent flats. The anatomy of this animal has been 
carefully described for us by Dr. Gunther. 
We have, then, in Australia what may be termed a triassic 
land, still showing us in life to-day the more or less modified 
representations of forms which elsewhere have long since passed 
away from amongst us, leaving but rare and scattered fragments 
— relics 44 sealed within the iron hills.” 
No member of the Australian families of the kangaroo’s order 
has left its relics in European strata more recent than the 
secondary rocks. But the American family, Diclelphidce , is 
represented in the earliest tertiary period by the remains of an 
American form (a true opossum) having been found by Cuvier 
in the quarries of Montmartre. He first discovered a lower jaw, 
and, from its inflected angle, concluded that it belonged to a 
marsupial animal, and that therefore marsupial bones were 
hidden in the matrix. Accordingly he predicted that such bones 
would be found ; and, proceeding to remove the enveloping de- 
posit with the greatest care, he laid bare before the admiring 
eyes of the bystanders the proof of the correctness of his predic- 
tion. It is noteworthy, however, that had this fossil been that 
of an animal like the Tasmanian wolf, he would have been 
disappointed, as, though marsupial, it has, as has been already 
said, not marsupial bones , but cartilages. 
But relics of creatures more closely allied to the kangaroo 
existed in times ancient historically, though, geologically speak- 
ing, very recent. Just as in the recent deposits of South 
America we find the bones of huge beasts, first cousins to the 
sloths and armadilloes which live there now, so in Australia 
there lived beasts having the more essential structural charac- 
ters of the kangaroo, yet of the bulk of the rhinoceros. Their 
bones and teeth have been found in the tertiary deposits of 
Australia. They have been described by Professor Owen, and 
are now to be seen preserved in the British Museum and that 
of the Koyal College of Surgeons. It may be that other fossil 
forms of the middle mesozioc or even of triassic times may, as 
some believe, have belonged to creatures of the kangaroo’s family ; 
