430 THE POPULAR SCIENCE MONTHLY, 



still showing us in life to-day the more or less naodified representations 

 of forms which elsewhere have long since passed away from among 

 us, leaving but rai-e and scattered fragments relics " 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, Didelphklce, 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 intiected angle, concluded 

 that it belonged to a marsupial animal, and that therefore marsupial 

 bones w^ere 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 prediction. It is 

 noteworthy, however, that, had this fossil been that of an animal like 

 the Tasmanian wolf, he Avould have been disappointed, as, though 

 marsupial, it has, as has been already said, not marsupial bodies, but 

 cartilages. 



But relics of creatures more closely allied to the kangaroo existed 

 in times ancient historically, though, geologically speaking, very re- 

 cent. 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 es- 

 sential structural characters 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 Prof. Owen, and 

 are now to be seen preserved in the British Museum and that of the 

 Royal College of Surgeons. It may be that other fossil forms of the 

 middle mesozoic or even of triassic times may, so some believe, have 

 belonged to creatures of the kangaroo's family ; but at least there is 

 no doubt that such existed in times of post-tertiary date. 



As to our third point the geological relations of the kangaroo 

 we may say, then, that " the kangaroo is one of an order of animals 

 ichich ranged over the Northern Hetnisphere in triassic and oolitic times, 

 one exceptional family lingering in Europe to the Eocene period, and 

 in America to the present day. That the kangaroo itself is a form 

 certainly become fossil in its oion region, where, in times geologically 

 recent, creatures allied to it, but of vastly greater bidk, frequented the 

 Australian j^lains.^^ 



"We may now, then, proceed to answer finally the question, " What 

 is a kangaroo f " We may do so because tlie meaning of the techni- 

 cal terms in which the answer must necessarily be expressed (if not of 

 undue length) has been now explained, as far as space has allowed. 



We may say, then, that ''the kangaroo is a didel^yhovs {or marsu- 

 pial) mammal, of the family Macropodid^; an inhabitant of the 



