GLOSSARY 233 



Cloaca: a tubular or saclike space which receives the discharge of various 



organs. 

 Clypeus: a median sclerite in the face of insects just back of the upper lip. 

 Cnidoblast: a stinging cell in Cnidaria which contains the nematocyst. 

 Cocoon: a case containing one or more developing animals. 

 Coelom: the body cavity. 



Collar: the ventral edge of the mantle in gastropods and cephalopods. 

 Colon: a division of the intestine. 

 Columella: the axis of a spiral snail's shell; a minute rodlike bone in the 



ear of frogs. 

 Compound eye: an eye made up of a number of separate elements, or 



ommatidia, in arthropods. 

 Conjugation: the fusion of two protozoans and interchange of nuclear 



matter. 

 Connective tissue: a tissue whose principal function is to support and hold 



in place other tissues and organs. 

 Coxa: the proximal segment of an insect's or a spider's leg, by which it 



articulates with the body. 

 Crop: a dilated portion of the oesophagus. 

 Ctenidium: a respiratory organ in mollusks. 

 Cuticula: the outer layer of the integument of most invertebrates. 

 Cyst: a capsule containing an animal usually in a state of suspended ani- 

 mation. 

 Cysticercus: a cyst containing a tapeworm scolex. 



Dentary apparatus: the five teeth and their supporting structure in the 



sea urchin. 

 Development: the series of changes in the early life of any animal by which 



it passes from the condition of a fertilized egg to that of the adult. 

 Dimorphism: the condition in which a species exists in two distinct forms, 



as, for instance, male and female. 

 Distal: a position away from the point of attachment — opposed to 



proximal. 

 Diverticulum: a saclike projection of a tubular organ. 

 Dorsal: on or toward the back. 

 Dorsal lamina: a ciliated ridge in the mid-dorsal line of the pharynx in 



the ascidian. 



Ectoderm: the outermost layer of cells in the Porifera and Coelenterata. 

 Ectosarc: the outermost layer of nongranular protoplasm in protozoans. 

 Elytra: the hard wing-covers in beetles. 

 Embryo: a young animal which is passing through its developmental 



stages, usuaUy within the egg membranes or in the maternal uterus. 

 Encyst: the act of an animal in forming a cyst about itself. 



