INDEX 



459 



Veliidae, 254 



Venom, 237 



Vertebrae, 56; development of, dia- 

 gram, 59 



Vertel)rates, 37; evolution of, 144, 

 161; emergence of terrestrial, 147 



Vesalius, 8 



Vesperiilio nodula, 227 



Vestigial structures, 85 



Vilmorin, 353 



Vitamines, 431 



Yilis. labrusca, 344; V. vinifera, 345 



Volant animals, in adaptive radia- 

 tion, 253; dispersal, 260 



Volvox, 51, 54 



Wagner, Moritz, 388, 409 

 Wallabv, 219, 220 

 Wallace, 14, 250, 385, 393 

 Walter, 274, 356, 418 

 Warning colors, 242 

 Water, as environment, 148 

 Water lilies, 260 

 Weapons, origin of, 194 * 



Web of life, 230 



Weismann, 15, 269, 291, 405 

 Wheat, 316; pure lines of, S06 

 Whetham, 367 

 Whip-poor-will, 242 

 Wilder, H. H., 69, 72, 198 

 Wings of insects, 139, 229 

 Winship, 370 

 Wisdom teeth, 88 

 Wolves, 239 



Woodchuck, abnormal growth of in- 

 cisor, 212 

 Wrens, nesting habits of, 396 



Xerophytes, 224, 226 

 X-rays, 116, 320, 419 



Yolk, 40 



Yolk sac, 45; human, 46 



Yucca, 226 



Zebra, 164, 183 



Zebu, 347 



Zoogeographical realms, 255, 256 



Zygote, 326 



