258 GLOSSARY 



Gonophore. In coelenterates, the specialized form which produces the 

 sex cells; whether a free-swimming medusa or any of the various 

 intermediate stages between it and the sporosac. 



Gonosome. The assemblage of structures directly connected with sexual 

 reproduction in hydroids. The comprehensive term which includes 

 gonophores, blastostyles, ovaries, gonangia, etc. 



Gonotheca. The chitinous covering of a gonozooid in calyptoblastic 

 hydroids. 



Gonozooid. The reproductive zooid in coelenterates. 



Green gland. In certain crustaceans, a paired excretory gland, the duct 

 of which opens to the outside at the base of the second antenna. 



Gullet. Esophagus. 



Gut. Digestive tube. 



Gymnoblastic. Lacking hydrothecae and gonothecae. 



Head. The more or less differentiated anterior end in bilaterally sym- 

 metrical animals. 



Hepatic caeca. Digestive glands opening in the stomach in certain 

 echinoderms. 



Hermaphrodite. An individual in which both male and female gonads 

 are present. 



Holophytic. The nutrition characteristic of green plants. 



Holozoic. The nutrition characteristic of animals. 



Homologous. Of similar structure or origin. 



Host. The organism which harbors a parasite. 



Hyaline. Transparent, glassy. 



Hydranth. An individual of a hydroid colony. 



Hydrocaulus. The stem of a hydroid colony. 



Hydrophyllium. A disk-shaped protective structure covering other 

 parts of the cormidium in a siphonophore. 



Hydrorhiza. The rootlike attachment of a hydroid colony. 



Hydrotheca. The chitinous covering of a vegetative hydranth in 

 calyptoblastic hydroids. 



Hypodermis. The single-layered integument in invertebrates possess- 

 ing a cuticle. 



Hypopharynx. A projection borne on the lower side of the pharynx of 

 some insects. 



Hypostome. In a rrydranth, the projection which bears the mouth. 



Incurrent canal. A canal that admits water to a sponge. 

 Integument. Outer covering of an animal. 



Interambulacral area. One of the areas of an echinoderm which lies 

 between adjacent ambulacral areas. 



