GLOSSARY. 183 



Cardiac division of stomach. Anterior or first division. 

 Carpopod. Fifth segment from the body of the leg of a crustacean. 

 Cellulose. The material that forms the walls of plant cells. 

 Cephalont. Attached stage in the life-history of Gregarina. 

 Cephalothorax. Fused head and thorax of many crustaceans. 

 Cervical groove. A groove that marks the boundary between the head 



and thorax of some crustaceans. 

 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 Arachnoidea. 

 Chitin. The material that forms the outer covering of insects and other 



animals. 

 Chlorogog. Excretory cells on the intestine of certain annelids. 

 Chlorophyl. The green coloring-matter of plants. 

 Choanocyte. A cell provided with a "collar." 

 Chromatophore. A body in which chlorophyl is lodged. 

 Cilia. Small vibrating appendages of cells. 

 Cinclides. Minute openings in the body-wall of coelenterates. 

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



canal that surrounds the mouth of an echinoderm. 

 Circumferential canal. Marginal canal of a medusa. 

 Cirrus. A soft tactile appendage. 

 Cleavage. The act of cell division. 

 Clitellum. The thickened glandular region on an earthworm that secretes 



the egg case. 

 Cloaca. A space that receives the discharge from the alimentary canal 



and kidneys, and frequently from other organs. 

 Cnidocil. The trigger of a nematocyst. 

 Coelenteron. The internal space of a coelenterate. 

 Coelom. Body-cavity; the cavity between the alimentary canal and 



body-wall. 

 Coenosarc. The fleshy continuation of a hydroid into the stalk. 

 Collar-cell. A cell provided with a collar; choanocyte. 

 Colon. Hinder part of the alimentary canal. 



Columella. Axis around which the spire of a gastropod shell is wound. 

 Commensal. Organisms living together and usually partaking of the 



same food. 

 Commissure. A nerve connecting two ganglia of a pair. 

 Compound eye. Eye of an arthropod that is composed of many similar 



pieces, called omatidia. 

 Connecting canal. The canal that joins the tube foot to the radial canal 



of an echinoderm. 



