254 GLOSSARY 



Cephalont. Attached stage in the life history of Gregarina. 

 Cephalothorax. Fused head and thorax in many crustaceans. 

 Cervical groove. A groove, in the carapace, which marks the boundary 



between the head and the thorax. 

 Chela. Large claw of many crustaceans ; also applied to pincer-like claws 



on other appendages. 

 Chelate. Bearing pincer-like claws. 



Chelicera. One of the anterior pair of mouth appendages of Arachnida. 

 Chitin. The material which forms the outer covering of insects and 



many other invertebrates. 

 Chlorogogue. Modified cells of the peritoneal covering of the intestine 



in annelids. 

 Chlorophyl. The green coloring matter of plants. 

 Chloroplastid. One of the chlorophyl-containing bodies within certain 



cells of green plants. 

 Choanocyte. A "collar cell." e. g., Choanoflagellates and the gastric 



layer in sponges. 

 Chromatophore. In zoology, a pigment-bearing tissue element or cell; 



in botany, a colored body or plastid found commonly in plant cells, 



e. g., a chloroplastid. 

 Cilia (sing., Cilium). Minute, hairlike, motile, protoplasmic processes 



of cells, e. g., ciliate protozoa. Also widespread throughout the 



animal kingdom. 

 Cinclides (sing., Cinclis). Minute openings in the body wall of sea 



anemones. 

 Circular canal. Marginal canal of a medusa; also applied to the water 



canal which surrounds the mouth of an echinoderm. 

 Circumferential canal. Circular canal of a medusa. 

 Cirrus. A soft, elongate outgrowth or appendage; in protozoa, an 



organelle composed of a cluster of fused cilia. 

 Cleavage. Eapid cell division not accompanied by growth. 

 Clitellum. The thickened, glandular region which secretes the cocoon 



of an earthworm. 

 Cloaca. The modified posterior part of the alimentary canal which 



receives products from the excretory organs and frequently from 



other organs. 

 Cnidoblast. Stinging cell in coelenterates. Contains the nematocyst. 

 CnidociL Slender process of a cnidoblast, stimulation of which may 



cause the ejection of the nematocyst. 

 Coelenteron. The digestive cavity of a coelenterate. 

 Coelom or true body cavity. The cavity between the alimentary canal 



and the body wall. Lined with mesoderm. 

 Coenosarc. The living part of the stalk of a coelenterate. It is con- 

 tinuous with the polyps. 



