COMPARING FEET. 



95 



close cousins of the sandpipers, have the webbing extended 

 along both sides of their toes, in a scalloped edge. 



Again we find another variation for increasing the surface 

 in the excised tveb, in which the space between the toes is still 



Fig. 22. Excised Web Foot of 

 Black Tern (Life Size). 



Fig. 23. Palmate or Webbed Foot 

 OF Duck (reduced). 



more filled up, though the word signifies that the foot looks as 



if it had once been full-webbed and then cut out, or excised. 



In the ducks and geese we see the webbing carried out to the 



toe-nails, and the surface increased by spreading the toes wide 



apart. In the loons it is still further increased by lengthening 



the toes, which make the 



webs long as well as wide. 



But one other device seems 



possible, and that we find in 



the totipalmate birds, where 



all four toes are joined by 



the web. Observe, please, 



that in these the outer toe is 



longest while in all other web- footed birds the third, or middle, 



toe exceeds the others. 



Most palmate birds swim with alternate strokes, now right, 

 now left, or with one foot a little behind the other, seldom 

 with both exactly together. The swans often swim with only 



Fig. 24. Totipalmate Foot of 

 Gannet (greatly reduced). 



