GLOSSARY 695 



Cheliped. The large grasping claw in many crustaceans. 



Chitin. A hard and very resistant substance present in the cuticula of many 



arthropods. 



Chlorophyll. The green coloring matter of plants. 

 Chromatophores. Colored pigment cells. 

 Cilia. The numerous vibratory projections on both the inner and the outer 



surfaces of certain animals. 

 Cirrus. A filamentous, sensory appendage of annelids; a protrusile copulatory 



organ of flatworms. 

 Clitellum. A thickened glandular region on oligochaets which secretes the 



cocoon. 

 Cloaca. A tubular or sac-like space which receives the discharge of various 



organs. 



Cnidoblast. A stinging cell in Cnidaria which contains the nematocyst. 

 CnidocU. A minute spine projecting from a nettle cell into the water. 

 Cocoon. A case containing one or more developing animals. 

 Caelom. The body-cavity. 



Caenenchym. The soft parts of an alcyonarian colony. 

 Collar. The ventral edge of the mantle in gastropods and cephalopods; the 



part of the body of Balanoglossus between the proboscis and the trunk. 

 Collar cell. A flagellate cell with a high membrane around the base of the 



flagellum. 



Colon. A division of the intestine. 

 Columella. The axis of a spiral snail shell. 



Complementary male. A minute accessory male animal in certain barnacles. 

 Compound eye. An eye made up of a number of separate elements, or omina- 



tidia, 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 arthropod's leg, by which it articulates 



with the body. 



Coxal plate. A plate in the ventral surface of Acarina. 

 Craspedote medusa. A medusa with a velum, a hydromedusan. 

 Cribellum. A plate with spinning tubes in front of the spinnerets in some 



spiders. 

 Cribriform organs. Parallel, vertical rows of thin calcareous plates in the 



margins of the arms of certain starfish. 

 Crop. A dilated portion of the O3sophagus. 

 Ctenidium. The molluscan gill. 



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

 Cyst. A capsule containing an animal usually in a state of suspended anima- 

 tion ; a capsule containing a foreign or inert body imbedded in some animal 



tissue. 

 Cysticercoid. A minute bladder worm in which the scolex completely fills the 



cyst. 

 Cysticercus. A bladder worm in which the cyst contains one or more scolices 



and a fluid. 



Dart sac. A part of the genital tract of certain pulmonate snails. 



Dentary apparatus. The five teeth and their supporting structure in the sea- 

 urchin. 



Desor's larva. A nemertean larval form. 



Development. The series of changes in the early life of an animal by which 

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



