GEOLOGICAL PERIODS. 59 



these again, the lancelet and its congeners were 

 evolved, — and from these lowest vertebrate forms, 

 Selachian and Ganoid fishes which existed in the 

 Silurian period, descended. 



As yet all organised and living beings were in- 

 habitants of the waters. 



To the Primordial time succeeded the Paleo- 

 lithic, or Palaeozoic or Primary, comprising- the 

 Devonian, Carboniferous, and Permian periods. The 

 Palaeolithic time was much shorter in duration than 

 the Archolithic, but longer than the subsequent times. 

 In the Carboniferous period existed Amphibia, the 

 most ancient land and air-breathing vertebrates. 



In the Mesolithic time, comprising the Triassic, 

 Jurassic, .and Chalk periods, osseous fishes first ap- 

 peared, but this time was, in an especial degree, that 

 of reptiles — the gigantic dragons and so-called flying 

 lizards. During this time also birds began to appear 

 as offshoots from lizards, of which the Archeopteryx 

 is an example — a bird with a lizard's tail. Mammals 

 also appeared in the form of marsupialia. 



In the Caenolithic or Tertiary time, compris- 

 ing the Eoccsne, Mioccsne, and Pliocmie periods, which 

 was short, mammiferous animals lived in full develop- 

 ment, and the transition from apes to man commenced. 



The next, or Quaternary time may, Haeckel 

 suggests, be designated the Anthropolithic, as it 

 was the time when men, endowed with the faculty of 

 speech, were evolved from speechless ape-men, and 

 when the full development of the various human 



