210 INVERTEBRATE ZOOLOGY 
Cocoon: a case containing one or more developing animals, 73. 
Caecum: a sac-like appendage of the digestive tract; grasshopper, 15, 
starfish, 145. 
Celom: the body-cavity. 
Collar: the ventral edge of the mantle in gastropods, 113 ; in cephalopods, 
124. 
Collar cells in sponges, 183. 
Colon: a division of the intestine in insects, 15. 
Columella: the axis of a spiral snail’s shell, 113. 
Compound eye: an eye made up of a number of separate elements, or 
ommatidia, in arthropods; wasp, 2; grasshopper, 9; crayfish or 
lobster, 29. 
Conjugation: the fusion of two protozoans and interchange of nuclear 
matter; Paramecium, 187; Vorticella, 190; Amoeba, 196. 
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, 4, 12, 25. 
Crop: a dilated portion of the cesophagus; grasshopper, 15; earthworm, 71. 
Ctenidium: a respiratory organ in mollusks; mussel, 93; clam, 107. 
Cuticula: the outer layer of the integument of most invertebrates; wasp, 1; 
beetle, 5; fly, 7; grasshopper, 10; spider, 24; crayfish or lobster, 28; 
Nereis, 61; earthworm, 74; Bugula, 85; mussel, 89; clam, 103; snail, 
112; Molgula, 136; tubularian, 166; campanularian, 170; Parame- 
cium, 185; Vorticella, 189; Euglena, 192. 
Cyst: a capsule containing an animal usually in a state of suspended ani- 
mation; tapeworm, 83; Euglena, 193. 
Cysticercus: a cyst containing a tapeworm scolex, $4. 
Dentary apparatus: the five teeth and their supporting structure in the 
sea urchin, 151. 
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, 1389. 
