3IO STUDIES IN THE EVOLUTION OF ANIMALS 



rupeds. In the Early Tertiary both the fangs and crowns of their 

 teeth were short, and as they progressed their teeth became longer, 

 so that their lives became longer also, as their teeth did not wear 

 away so quickly. Moreover, the Early Tertiary quadrupeds, 

 although of large size, had small brains, and this condition was 

 also conducive to a short life, for in the struggle for existence the 

 animal with a large brain has always been able somehow to circum- 

 vent the one with a small brain. The early types had no horns. 



There seems to me two weak points regarding this theory of 

 a sunken continent in the Pacific Ocean. 



(a) If highly specialised types existed on this Pacific continent, 

 what prevented their migrating before that particular time ? Was 

 it the isolation of the continent ? If so, when it began to sink it 

 would become more isolated ! Of course it may be said that the 

 continent was not wholly isolated, but in some place connected 

 with other continents by a neck of dry land such as that which 

 connects Africa with Asia : and that when a portion of this lost 

 continent began to sink, that is, when the grazing or feeding 

 grounds of those animals began to be swallowed up by the sea, 

 and their numbers continuing undiminished, hunger forced them 

 either to die or to migrate by some land communication. There 

 is, however, another and a weaker point in this theory. 



ib) Concurrently with the appearance of a new type of quad- 

 rupeds in the New and Old Worlds there appeared a new type of 

 plants. From the previous C}'cads, which are rather fern-like, we 

 pass, without any local predecessors, to plants, which are more or 

 less like those we have now, that is, flowering plants. 



We now know that a large number of seeds of flowering plants 

 can be transported long distances by strong winds and cyclones, 

 and even on the mud that sticks to the feet of water-birds and 

 evaders, and in some cases on their feathers also. 



