186 GLOSSARY. 



Gastro-vascular. Digestive and circulatory in function, as the gastro- 



vascular cavities of coelenterates. 

 Gastrozooid. Feeding individuals of hydroids. 



Genital atrium. A space receiving the genital ducts. See Bdelloura. 

 Genital gland. A gonad. 

 Genital plate. One of the plates through which the gonads open in 



echinoderms. 

 Genital pore. The opening in the genital plate or other external opening 



of a gonoduct. 

 Gill. Aquatic respiratory organ. 



Gizzard. A muscular triturating division of the alimentary canal. 

 Gonad. A generative tissue, a germ gland. 

 Gonangium. A reproductive individual of the Hydrozoa. 

 Gonotheca. The transparent covering of a gonangium. 

 Green gland. One of the excretory glands of certain crustaceans. 

 Gullet. Esophagus; the tube leading back from the mouth or pharynx. 

 Gut. Digestive tube. 



Head. The anterior division of the body of higher animals 



Hepatic caecum. Digestive gland of a starfish. 



Hermaphrodite. With male and female sexual organs. 



Holophytic. The nutrition characteristic of plants. 



Holozoic. The nutrition characteristic of animals. 



Homologous. Of similar structure. 



Host. The animal that harbors a parasite. 



Hyaline. Transparent, glassy. 



Hydranth. An individual of a hydroid colony. 



Hydrocaulus. The stem of a hydroid colony. 



Hydrorhiza. The projections by which hydroid colonies are attached. 



Hydrotheca. The outer secreted covering or cup of a hydranth. 



Hypobranchial gland. A gland near the gill of some gastropods. Some 

 lamellibranchs have glands that bear the same name. 



Hypodermis. A cellular layer that lies just beneath the cuticle of anne- 

 lids, arthropods and some other animals. 



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

 some insects. 



Hypophysis. A ventral projection from the brain of Chordata. 



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

 Integument. Skin; outer covering. 



Inter-ambulacral area. One of the areas of an echinoderm that lies 

 between adjacent ambulacral areas. 



