THE DAWN OF THE EVOLUTIONARY PERIOD. 231 



Some birds have acquired harder beaks to crack nuts, 

 as the parrot. Others have acquired beaks adapted 

 to break the harder seeds, as sparrows. Others, fqr 

 the softer seeds of flowers, or the buds of trees, 

 as the finches. Other birds have acquired long beaks 

 to penetrate the moister soils in search of insects or 

 roots, as woodcocks ; and others, broad ones to filtrate 

 the water of lakes, and to retain aquatic insects, as 

 ducks. All which forms seem to have been gradually 

 produced during many generations by the perpetual 

 endeavour of the creatures to supply the want of food, 

 and to have been delivered to their posterity with 

 constant improvement of them for the purposes required. 



'The third great want among animals is that of 

 security, which seems much to have diversified the 

 forms of their bodies and the colour of them; these 

 consist in the means of escaping other animals more 

 powerful than themselves. Hence some animals have 

 acquired wings instead of legs, as the smaller birds, 

 for the purpose of escape. Others, great length of fin 

 or of membrane, as the flying-fish and the bat. Others, 

 great swiftness of foot, as the hare. Others have acquired 

 hard or armed shells, as the tortoise and the Echinus 

 marinus [the sea-urchin]. Mr Osbeck, a pupil of 

 Linnaeus, mentions the American frog-fish, Lophius 

 histrio, which inhabits the large floating islands of sea- 

 weed about the Cape of Good Hope, and has fulcra 

 resembling leaves, that the fishes of prey may mistake 

 it for the seaweed which it inhabits. 



'The contrivances for the purposes of security extend 

 even to vegetables, as is seen in the wonderful and 



