GLOSSAEY. 297 



Vestibule. A cavity within the ear. 



Vexillum. The web, composed of barbs, with its scape or rhachis, 



of a feather. 

 Vibracula. A peculiar cup-shaped appendage in the Polyzoa, to 



which is attached a movable seta. 

 Vibrissce. Stiff hairs ; a general term. 

 Viscera. Internal organs, especially those within the thorax and 



abdomen. 



Vitellus. The yolk of an egg. 

 Vomer. A bone forming part of the septum of the nares, and 



connected more or less with the palatine bones. 



Wallace's line. A line which is assumed to divide the " Malayan " 

 from the " Austro-Malayan " regions. It passes between Bali 

 and Lombok in the south, through the Macassar Straits, di- 

 viding Borneo from Celebes, and to the north-east between 

 Mindanao and Grilolo. 



Yellow cells or sarcoblasts. Peculiar nucleated structures in the 

 Eadiolaria, containing yellow protoplasm (possibly parasites). 



Zoanthodeme. The body formed by the coherence of many zooids 

 of a single polyp of an Actinozoon. 



Zoarium. See Ccenoecium. 



Zo'ea. An intermediate larval stage in the higher Crustaceans. 



Zonites, Somites, or Metameres. See Segments. 



Zocectum. A cell in which a polypide of the Polyzoa is lodged. 



Zooid. '' A term applied to the individuals of compound or- 

 ganisms, as the polyps of a polypidom" (Huxley). "The de- 

 tached portions of an individual in discontinuous develop- 

 ment" (Greene). "The more or less independent products of 

 non-sexual reproduction " (At/man). Zooid is a name given 

 also to the central basis of a blood-corpuscle. 



Zoology. The science of animals. 



Zoomorphism. The series of changes in the life of an animal. 



Zoon. Mr. Herbert Spencer's name for "the whole product of a 

 fertilized germ." 



Zootheme. The compound animal mass produced by budding. 



Zygapophyses. Certain processes of the vertebrae. 



Zygosis. See Conjugation. 



