2 ELEPHANTS. 



the dates of the documents upon which it is founded must 

 be known. It will be seen from Table 1 that the history 

 of the life of the Earth falls into several great periods, to 

 which names have been given by geologists. The earliest of 

 these is called the Primary or Palaeozoic Period, and during 

 it the only backboned animals were fishes, amphibians (repre- 

 sented at the present time by newts, frogs, &c.), and, towards 

 the end, some reptiles. In the next great period, the Secondary 

 or Mesozoic, the reptiles were of the greatest importance : they 

 were very numerous and some were of gigantic size. They 



TABLE 1. 



f QUATERNARY f RECENT. 



1 PLEISTOCENE. > 

 C^NOZOIC <{ f PLIOCENE. 



LTEBTIABY.. - j Ml CENE - 



j OLIGOCENE, 

 I EOCENE. 

 f CRETACEOUS. 

 MESOZOIC or SECONDARY J j URAS sic. 



L TRIASSIC. 

 f PERMIAN. 



CARBONIFEROUS. 

 PALAEOZOIC or PRIMARY DEVONIAN. 



SILURIAN. 



ORDOVICIAN. 

 ^ CAMBRIAN. 



became fitted for various modes of life, some inhabiting the 

 land, others the sea; some living on a vegetable diet, others 

 on flesh. During this period also the birds began to come into 

 existence, and remains of the most remarkable of the early 

 forms of birds, Archaopteryx, are shown in table-case 13. At 

 the same time the first of the warm-blooded mammals arose, 

 though they were as yet insignificant in size and numbers. 

 The third period, the Caenozoic, is that with which we 

 are chiefly concerned. During this the reptiles lost their 

 importance, while, on the other hand, the mammals took 

 their place, becoming extremely numerous, many of them 



