GLOSSARY 55 



Gastric ridges: Ridges extending out into the digestive cavity 

 of certain coelenterate larvae. 



Gemmation: The process of forming small aggregates of proto- 

 plasm or of cells which are called gemmules. 



Gill books: Respiratory apparatus similar to lung books except 

 that water rather than air is introduced between the "pages." 



Gill slits: Openings from the pharynx to the exterior which are 

 typically used in gUl breathing as in fish. 



Gizzard: A thick- walled portion of the alimentary tract used in 

 mixing or grinding food. 



Gonads: Sex organs. 



Halteres: Knobbed filaments which take the place of a second pair 

 of wings as in flies. 



Heterocercal: A type of fish tail in which the dorsal lobe is larger 

 than the ventral and contains the continuation of the vertebral 

 column. 



Homocercal: A type of fish tail in which the two lobes appear 

 symmetrical as in most fishes. 



Hyaline: With glasshke transparency. 



Hydroid: Resembling the simple hydra, generally used to designate 

 a colonial coelenterate the individuals of which resemble 

 hydra in some respects. 



Incomplete metamorphosis: A term applied to the life-history of 

 certain animals, particularly- insects, in which the young 

 stages bear some resemblance to the adult animals. /v 



Integument: Outer covering, skin. ^/ ^Q\^ 



Intracellular: Lying within a cell. 







