GLOSSARY 383 



Gill cleft. One of several openings from the pharynx to the sides of the neck or head 



of a vertebrate embryo or adult; derived from a gill pouch. Also called gill slit. 

 Gill plate. The thickened patch of ectoderm in an embryo from which gills are 



developed. 

 Gill pouch. One of several evaginations from the sides of the anterior part of the 



digestive tract in the embryos of vertebrate animals. In some animals they 



break open to the outside, becoming gill clefts. 

 Gizzard. In the earthworm, a thick-walled portion of the alimentary tract behind 



the crop. In birds, the posterior muscular division of the stomach. 

 Gland. An organ whose function is the secretion of something to be used in, or ejected 



from, the body. 

 Glaucomys. A genus of flying squirrels. 



Glenoid fossa. The cavity into which the head of the humerus fits. 

 Glochidium (glo kid' i um). The young stage of a mussel, which becomes temporarily 



attached to fishes. 

 Glomerulus {glo mer' u lus). A coil of blood capillaries at the end of each tubule in 



the kidney of a vertebrate animal. 

 Glossozoa {glo' so zo' a). A group of animals (literally, tongue animals) in Oken's 



early classification. It comprised the fishes. 

 Glottis. A slitlike opening in the larynx at the anterior end of the trachea in 



vertebrates. 

 Glucose. Grape sugar. 

 Glycerol {glis' er ole). An alcohol entering into the composition of fats and having 



the empirical formula C3H!i(OH)3. Same as glycerin. 

 Glycine {glV seen). The simplest of the amino acids. 

 Glycogen {gW ko jen) . Animal starch ; a common form of stored carbohydrate food 



in animal tissues. 

 Gmelin, Johann {gma' lin). German botanist, 1748-1804. 

 Golgi apparatus {gole' jee). A structure of various shapes, often a network, and of 



unknown function, found in many cells, usually near the nucleus. 

 Gomphoceran {gam fas' er an) . Any extinct cephalopod resembling Gomphoceras, 



whose shell was short and wide. 

 Gonad {go' nad). An organ in which germ cells (either oogonia or spermatogonia) 



are produced or lodged. 

 Gonangium {go nan' ji um). A reproductive structure in a hydroid, consisting of a 



blastostyle, its attached medusa buds, and a gonotheca. 

 Goniatite {go' ni a tile). An extinct cephalopod having a coiled shell and bent or 



angular sutures; so named from the genus Goniatites {go' ni a ti' teez). 

 Gonionemus {go' ni o ne' mu-s). A genus of jellyfishes. 

 Gonium. A genus of colonial flagellate organisms in which the cells are arranged in a 



flattened plate. 

 Gonophore. One of the reproductive members of a siphonophore colony. Also, a 



medusa or medusalike member of a hydroid. 

 Gonotheca. A transparent sheath forming the outer part of a gonangium of a 



hydroid. 

 Gopherus {go' fer us). A genus of turtles. 

 Grantia. A genus of calcareous marine sponges. 



Graptemys {grap' te 7nis). A genus of turtles of the familj' Testudinidae. 

 Graptolite {grap' to lite). An extinct group of colonial hydroid coelenterates of 



Cambrian and Devonian time. 

 Graze. To eat grass or similar herbage. 

 Gregaloid. Loosely adhering in an irregular mass. 



