12 The Under-Water World 



existence. Amongst what we are pleased 

 to-day to designate as the lower animals 

 the mammals, birds, reptiles and 

 fishes, the same principle holds good. 

 Bulky and heavily armoured forms must 

 eventually give way to the more intelli- 

 gent antagonist however despicable his 

 physical development. It may be there- 

 fore argued that in view of the supremacy 

 of brain power over mere size, such 

 creatures as the molluscs and echinoderms 

 should have gone under at an early date, 

 instead of persisting as they do in 

 apparently as great abundance as ever 

 they did when the world was so to speak 

 in the making. But here again the life 

 force has been equal to the occasion, 

 and great as the death rate may be, the 

 birth rate is equal. The more complex 

 the development of the individual, the 

 lower the birth-rate. 



The development of armour that could 

 either be worn, as in the lobster, or 



