i88 THE STORY OF THE BIRDS 



legs of the greatest service as aids to swimming 

 and diving. These are placed so far back as 

 to render walking by no means easy or elegant 

 in the purely aquatic species ; but their adaptive- 

 ness to an aquatic existence is beyond criticism. 

 Their legs and feet are used as oars, modified 

 in various ways so that they may combine the 

 greatest power of propulsion in the backward 

 movement or stroke with the least degree of 

 resistance in the forward one. Many of these 

 birds (Divers for instance) are said to assume 

 a ventropodal position when on land, never 

 standing in an upright attitude ; but that this 

 is not invariably the case my own and others 

 observations prove beyond doubt. 



The usual modes of progress on land by birds 

 is either by running, walking, or hopping. We 

 cannot say that either mode of progression is 

 pecuHar to certain groups, or in many cases to 

 certain species, but generally speaking these 

 various methods of moving about are character- 

 istic of the following birds respectively. All the 

 Ratitae birds both walk and run, when the latter, 

 usually balancing themselves with their short 

 wings. Amongst Carinatae birds the typical 

 walkers, as they certainly are the most stately, 

 arc Cranes, Herons, Storks, Flamingoes, Bustards, 



