INDEX 



877 



Wing, 468, 492 



Wing beats, frequency of, 334 



Wing buds, 315 



Wing slots, 469 



Wishbone, 474 



Wolff, Kasper, 10, 133 



Wolffian ducts, 411, 431, 435, 559 



Woodchucks, 500 



Woodcocks, 482 



Woodpeckers, 483 



Worker termites, 344 



\Vorm, spiny-headed, 232 



Wuchereria, 811, 834 



X 



X chromosomes, 660 

 X organ, 329 

 Xenopsylla cheopis, 803 

 Xiphosura, 320, 835 



Y chromosomes, 660 

 Yolk, 120, 454 

 Yolk plug, 420 

 Yolk sac, 131, 455, 639 

 Yolk sac placenta, 436 

 Yucca moth, 787 



Zoantharia, 833 



Zoological Nomenclature, commission on, 



140 

 Zoolog)', applications of, 12 



histor)' of. 7 



subdivisions of, 1 

 Zygapophysis, 399, 508 

 Zygomatic arch, 510 

 Zygote, 114, 168, 420 



