270 GLOSSARY. 



Cterwcyst. A peculiar body in the Ctenophora. 



Ctenoid. Applied to fish-scales with a toothed or spinous 

 hinder margin. 



Ctenophores. Meridional bands, eight in number, bearing comb- 

 like fringes ; the organs of locomotion in the Ctenophora. 



Cuneus. A portion of the hemelytron of certain Hemiptera be- 

 tween the corium and the posterior membranous portion. 



Cycloid. Applied to fish-scales with a rounded entire hinder 

 margin. 



Cytoblast. See Nucleus. KLrrTot p <> 



Cytode. A plastide without a nucleus. A plastide with a nu- 

 cleus is a cell. Prof. Huxley holds that " the primary form of 

 every animal is a nucleated protoplasmic body, cytode or cell." 



Cytogenous. Producing cells. 



Cytostome. The point where the ingestion of food takes place in 

 the flagellate Infusoria. 



Dactylopodite. The seventh or terminal joint, exclusive of the 

 " fingers," in the leg of a Crustacean. 



Decidua. " The modified mucous membrane of the pregnant 

 uterus." 



Degradation. Eudimentary or abortive structural development. 

 Often due to parasitism. Not to be confounded with arrest of 

 development. 



Delamination. "The splitting into two layers of cells of a pri- 

 mitively single-layered blastoderm " (Huxley}. 



Dentine. The tissue forming the body of the tooth. 



Derivative theory as opposed to Natural Selection, holds " that 

 every species changes, in time, by virtue of inherent tendencies 

 thereto." 



Dermatosis. When the derm or skin forms a bony plate. 



Dertrum. The apex of a bird's bill. 



Deuterostomatous. When the mouth of the gastrula is secondary. 



Deuterozooid or proglottis. Zooids produced by gemmation from 

 zooids. 



Dialysis. The separation of parts previously joined together. 



Diaphragm. The muscle separating the thorax from the ab- 

 domen. 



Diaphysis. Ossification proceeding from the centre of a long 

 bone. 



