LIFE IN THE PAST 173 



ingly difficult to say much about it. There must have 

 been nothing but marine plants, and these must have 

 been on the general line of the seaweeds. Little can 

 be definitely said concerning them. 



The next period of the Palaeozoic is known as the 

 Devonian age, or the age of fishes. Now the back- 

 boned animals first make their clear and unmistakable 

 appearance. There are remains in the Silurian which 

 show that there must have been a few fishes at that 

 time. The Devonian is so full of them and they are 

 so well developed and so diversified that this period 

 is definitely known as the "age of fishes." They do 

 not closely resemble the fishes of to-day, but anyone 

 would recognize most of them for what they are. 

 Their bodies were covered, not so much with scales as 

 with heavy plates, often arranged like tiles, those on 

 the forward half of the animal being often larger 

 than those surrounding the rest of the body. The 

 creature was encased, as it were, in armor. These 

 were the rulers of the Devonian seas. The land, as 

 yet, was probably nearly without animal life, the 

 creatures thus far being* almost confined to the water. 

 A few insects make their appearance and a few thou- 

 sand-leggers are running around among the lowly 

 plants; a few spider-like animals have arisen; there 

 are a few snails that have left the water and taken 

 to the land. Altogether only the dawn of a land 



