216 GLOSSARY. 



Connective. A nerve connecting two ganglia not of a pair. 



Contractile vesicle. Contractile excretory organ of Protozoa. 



Copulation. Sexual union. 



Coxa. Basal segment of the leg of an insect. 



Coxopod. Basal segment of a leg of a crustacean. 



Crop. An enlargement of the alimentary canal used to store food. 



Crystalline style. A transparent rod frequently found in the alimentary 



canal of lamellibranchs. 

 Ctenophoral row. A row of swimming plates on a ctenophore. 

 Cuticle. Outside protective covering. 

 Cyst. A sac or pouch. 



Cystic duct. The duct that leads away from the gall-bladdei 

 Cysticercus. A stage in the development of many tapeworms. 



Dactylopod. Last segment, seventh, of a crustacean leg. 

 Dactylozooid. Elongated tentacle-like zooid of a siphonophore. 

 Denticle. Small, tooth-like protuberance, as in the pharynx of some 



annelids. 

 Dermal branchiae. Projections on the surface of the body that are used 



for respiration. See starfish. 

 Development. The series of changes that lead from the fertilized egg to 



the mature animal. 

 Digestive gland. Any gland that secretes a digestive fluid. 

 Dimorphism. Two distinct forms of individuals in the colony or species. 

 Dioecious. Sexes in two separate individuals. 

 Directive septa. Those placed opposite the siphonoglyphes of an actino- 



zoan. 

 Disk. The central portion of a starfish. 

 Dissepiment. A transverse partition in an annelid. 

 Distal. Remote from the point of origin or attachment. 

 Diverticulum. An out-pocketing from a tube. 

 Dorsal. Back. 

 Dorsal lamina. A ciliated ridge on the dorsal side of the pharynx of an 



ascidian. 

 Dorso-ventrally. From the dorsal to the ventral position 



Ectoderm. The outer embryonic layer. 

 Ectoparasite. A parasite on the outside of the body. 

 Ectoplasm. Outer layer of Amoeba and of other Protozoa. 

 Efferent. Going away, as a vessel that leads away from an organ. 

 Elytra. The modified fore- wings of a beetle. 

 Embryo. An immature animal. 

 Encyst. To inclose in a cyst. 



