194 INVERTEBRATE ZOOLOGY 



Coelom: the body-cavity. 



Collar: the ventral edge of the mantle in gastropods, 103 ; in cephalopods, 

 114. 



Collar cells, in sponges, 163. 



Colon: a division of the intestine in insects, 13. 



Columella : the axis of a spiral snail's shell, 103. 



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

 ommatidia, in arthropods; wasp, 2; grasshopper, 7; crayfish or 

 lobster, 23. 



Conjugation: the fusion of two protozoans and interchange of nuclear 

 matter; Paramecium, 167; Vorticella, 171; Amoeba, 176. 



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 leg, by which it articulates with 

 the body, 4, 10. 



Crop: a dilated portion of the oesophagus ; grasshopper, 13 ; earthworm, 65. 



Ctenidium: a respiratory organ in mollusks; mussel, 87 ; clam, 97. 



Cuticula : the outer layer of the integument of most invertebrates ; wasp, 1 ; 

 beetle, 5 ; grasshopper, 8 ; crayfish or lobster, 23 ; Nereis, 55 ; earth- 

 worm, 61 ; Bugula, 79 ; mussel, 83 ; clam, 93 ; snail, 102 ; Molgula, 

 126; tubularian, 152; campanularian, 156; Paramecium, 165; Vorti- 

 cella, 169 ; Euglena, 172. 



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

 mation ; tapeworm, 78 ; Euglena, 173. 



Cysticercus : a cyst containing a tapeworm scolex, 78. 



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



urchin, 141. 

 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. 

 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 sac-like projection of a tubular organ. 

 Dorsal : on or towards the back. 

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



ascidean, 130. 

 Ductus ejaculatorius : the terminal portion of the male reproductive tract in 



insects, 15. 



