704 



INDEX. 



White rats, 639 

 Wiiiiipipe, 547 

 Winter eggs, 416 

 Wisdom tootli. 650 

 Wish bone, 605 

 Wolff, 17 



Wolffian body, 550 

 Wolffian duct, 550 

 Wolves, 647 

 Wombat, 633 

 Woodcock, 615 

 Woodpeckers, 616 

 Wool, 618 

 Worms, 182 

 Wotton, 9 

 Wrens, 616 

 Wrisberg, 13 



Xenarthra, 636 

 Xenos, 483 

 Xenurus, 636 

 Xerobates, 596 

 Xiphiidse, 577 

 Xiphisternum, 595 

 Xiphosura, 444 



Yellow cells, 195 

 Yellow fever, 492 

 Yoldia, 366, 367 



Yolk, 80 



Yolk and segmentation, 151 



Yolk granules, 81 



Yolk membrane, 148 



Yolk sac, 553 



Zebra, 641 

 Zeuglodonta, 646 

 Zoantharia, 259 

 Zoantheae, 259 

 Zoea, 413 



Zonary placenta, 634 

 Zonuridze, 599 

 Zoology, I, 5 

 Zoology, history of, 6 

 Zoology, purpose of, I 

 Zoophaga, 633 

 Zoophytes, 171, 228 

 Zoospore, 185, 188, 195 

 Zoothamnion, 211 

 Zootomy, beginning of, 13 

 Zooxanthellte, 170, 195 

 Zygssna, 571 

 Zygapophysis, 519 

 Z3'gobranchia, 378 

 Zygodactyl foot, 614 

 Zygomatic arch, 526 

 Zygomatic bone, 526 



