ADAPTATION TO HAUNTS 



147 



are less divergent from the ordinary Carinate type as regards 

 both fore and hind hmbs. 



It is instructive to take a particular case in more detail — 

 puffins, for instance. These attractive birds have short, 

 narrow wings, but their flight is rapid and often zigzag, that 

 is to say, under rapid control. When they launch themselves 

 from a cliff, head bent down, wings raised up, webbed feet 

 spread out behind, they often describe a fine whirring sweep 

 before they alight with a splash in the sea. They paddle 







^^N 



Fig. 35. — Wing of Adelie Penguin, Pygoscelis adeliEe. A., from a 

 specimen; b., after Pycraft. A novel structure, a flipper, has arisen 

 from a typical wing, without very radical transformations, h., humerus ; 

 R., radius; u., ulna; r., radiale ; 11., ulnare ; cmc, carpometacarpus ; 

 I., the thumb; ph.i., the first joint of the first finger; 11., the second 

 joint ; III., the second finger or third digit. 



deftly on the surface with their feet, but they swim under- 

 neath the water with their wings. Indeed, it may almost be 

 said that they fly under water. Unless helped by a head 

 wind, they find it difficult to rise into the air, and they often 

 splash along for some distance before they are clearly 

 launched in flight. But they often fly several miles to the 

 fishing ground many times in a day. Sometimes a large 

 flock may be seen wheeling in unison, recalling the fact that 

 auks (the family to which puffins belong) are related to the 

 gregarious plovers. To this repertory of movements there 

 has to be added the burrowing, for the nest is often at the 

 end of a yard long tunnel. In the tunnelling, which is said 



