6o8 



INDEX 



X ellow cells : of Radiolaria, 

 299 ; of Earthworm, 323, 327, 332 



Yolk, yolk-granules or spheres, 195, 

 546 ; and see under various 

 types 



Yolk-cells, 200, 202 



Yolk-plug, 201 



Yolk-sac, 454 



/^ooid 



Z 



,ooid, 281 ; and see Megazooid 

 and Microzooid 

 Zoology, I 

 Zoophytes, see Hydroid polypes. ' 



Zooxanthella, 299 



Zygapophysis; 36, 481 



Zygoma": zygomatic arch, 477, 478, 



Zygote, 197, 279 



THE END. 



RICHARD CLAY AND SONS, LIMITED, LONDON AND BUNGAY. 



