Vol. XXIXI 



1912 



J TowNSEND, Bird Genealogy. 287 



primitive one, as indeed it must be, then birds that swim in an 

 erect Duck-like manner must have advanced beyond this stage 

 and become speciaUzed. I have several times seen young Spotted 

 Sandpipers that were unable to fly, swim with ease like little 

 Ducks, although when very young and much frightened they 

 return to the primitive reptilian scramble on all fours. All of 

 the members of the Shore Bird family swim naturally if they find 

 themselves in water beyond their depths. Phalaropes habitually 

 disport themselves on the surface of the water as gracefully as 

 miniature Swans. It would seem to be a natural inference, there- 

 fore, that the ancestors of Shore Birds were swimmers and that 

 the art of swimming is inherited and not developed by this group, 

 and that the Phalarope is a case of reversion. The awkward 

 action of a young seal at its first bath is an example of a case where 

 the art of swimming has been recently acquired by a group and 

 where it is not one of long inheritance. 



In the classification of birds proposed by Hans Gadow the order 

 Charadrii formes, or Plover-like birds, includes the Shore Birds, 

 Gulls, Auks and Pigeons. The Shore Birds, we have just seen, 

 show evidence of a swimming ancestry, although, with the excep- 

 tion of the Phalaropes, they habitually prefer the shore under their 

 feet, even if it is wet and partly covered with water, to the deep 

 sea. The presence of partial webs, as in the Willet and in the 

 Semipalmated Plover and Sandpiper, point to the former existence 

 of the swimming habit, for these birds like other Shore Birds do 

 not swim except when unexpectedly forced to it. 



If the partial web in the foot of the adult Shore Bird showed the 

 beginning of the swimming habit in birds of land ancestry we 

 should find the young birds like young seals very inexpert in the 

 water. As the reverse of this is the case our conclusion that 

 these birds are of water ancestry must be correct. 



Gulls and Terns have fully webbed feet but their habits at the 

 present day hardly justify them in this possession. Webbed feet 

 are of great advantage to the rapidly swimming bird and to the 

 diving bird that depends on its feet. Now Terns rarely rest on the 

 water or swim and Gulls do not often swim rapidly, in fact they 

 rarely swim at all, but drift about, while if either bird descends 

 below the surface, it is as a result of the velocity of its plunge from 



