HOW EXTINCT MONSTERS ARE PRESERVED. 19 



are much more likely to contain the remains of land animals, 

 than those that were formed in seas, and they are more likely 

 to be in a complete state of preservation. Within the last 

 century, five or six small lakes in Scotland, which had been 

 artificially drained, yielded the remains of several hundred skeletons 

 of stags, oxen, boars, horses, sheep, dogs, hares, foxes, and 

 wolves. There are two ways in which these animals may have 

 met with a watery grave. In the first place, they may have got 

 mired on going into the water, or in trying to land on the other 

 side, after swimming across. Any one who knows Scotch lakes 

 will be familiar with the fact that their margins are often most 

 treacherous ground for bathers. The writer has more than once 

 found it necessary to be very cautious on wading into a lake 

 while fishing, or in search of plants. Secondly, when such lakes 

 are frozen over in winter, the ice is often very treacherous in 

 consequence of numerous springs; and animals attempting to 

 cross may be easily drowned. No remains of birds were dis- 

 covered in these lakes, in spite of the fact that, until drained, 

 they were largely frequented by water-fowl. But it must be 

 remembered that birds are protected by their powers of flight 

 from perishing in such ways as other animals frequently do. 

 And, even should they die on the water, their bodies are not 

 likely to be submerged ; for, being light and feathery, they do 

 not sink, but continue floating until the body rots away, or is 

 devoured by some creature such as a hungry pike. For these 

 reasons the remains of birds are unfortunately very rare in the 

 stratified rocks ; and hence our knowledge of the bird life of 

 former ages is slight. 



THE IMPERFECTION OF THE RECORD. 



A very little consideration will serve to convince us that the 

 record which Nature has kept in the stratified rocks is an incom- 

 plete one. There are many reasons why it must be so. It is 



