412 
Trajectory of wing, 218-223 
Turnstone, 352 
VALVES of heart, 72, 73 
of veins, 71 
Veins, 70, 71 
Ventricle of heart, 69 
WADERS, 386 
Warblers, 359 
Warm-blooded animals, 48, 96, 
104, 105 
Water-ouzel, 387 
Weight and wing area, 261 
Wind (see Flight), 231, 234, 235, 
237 
THE 
INDEX 
Windpipe, see Trachea 
Wing, ‘area of, 261 il 
Digits of, 209, 210 
as leyer,173- 180. 
Membranes of, 201 
Narrow, 190 , 
Trajectory of, 218-223 
Wings, move unequally (2 ), 250 
Woodpeckér, 62, 154, 163-165; ai? 
386 
Wren, Golden-crested, 226, 295, 
349 
YOLK, 277 
Yolk-sack, 281 , 
Young birds, 108, 286 
END 
RICHARD CLAY AND SONS, LIMITED, LONDON AND BUNGAY. - 
