xv i LIST OF ILLUSTRATIONS. 



FIG. PAGE 



22. Curved bill of female, straight bill of male Iluia-bird . . 33 



23. Feathers from back of Snowflake, showing seasonal changes in 



form and color due to wearing off of tips . . . .38 



24. Eggs of (a) Spotted Sandpiper and (b) Catbird, to show differ- 



ence in size of eggs of praecocial and altricial birds of same 

 size 68 



25. Topography of a bird . . . . . . . . .71 



