214 INVERTEBRATE ZOOLOGY 



Interray: one of the divisions of the radiate body of echinoderms; starfish, 

 142 ; sea urchin, 150 ; sea cucumber, 155. 



Intestine : the division of the digestive tract in which absorption goes on ; 

 spider, 27; crayfish or lobster, 37; copepod, 55; planarian, 77; Bugula, 

 86 ; mussel, 96 ; oyster, 101 ; clam, 110 ; snail, 118 ; squid, 131 ; Mol- 

 gula, 137 ; starfish, 145 ; sea urchin, 152 ; sea cucumber, 156. 



Kidney : an excretory organ ; spider, 27 ; crayfish or lobster, 40 ; Nereis, 

 65 ; earthworm, 73 ; mussel, 95 ; clam, 109 ; snail, 116 ; squid, 127 ; 

 Molgula, 138. 



Labium : the under lip of insects ; fly, 8 ; grasshopper, 12 ; beetle, 14 ; 



wasp, 14 ; caterpillar, 20 ; spider, 25. 

 Labrum : the upper lip of insects and of some crustaceans ; grasshopper, 



12 ; beetle, 14 ; wasp, 14 ; caterpillar, 20 ; crayfish, 30. 

 Lamella : a leaf -like or plate-like structure, 90, 104. 

 Larva : a young animal which has left the egg and is leading a free life, 



but which has not yet completed its development ; decapods, 51 ; ento- 



mostracan, 59 ; tapeworm, 84 ; mussel, 97 : a holometabolic insect 



between the embryonic and the pupal stages, 20. 

 Lateral : a position to the right or left of the median line. 

 Ligula : the anterior portion of the labium in insects ; grasshopper, 13 ; 



wasp, 14. 

 Lithocyst : a marginal sense-organ in certain medusae, 173, 176. 

 Liver : a digestive gland ; crayfish or lobster, 39 ; crab, 44 ; Daphnia, 57 ; 



mussel, 96; oyster, 101; clam, 107; snail, 119; squid, 131; starfish, 145. 

 Lophophore : a circular or horseshoe-shaped ridge bearing tentacles in 



Bryozoa, 86. 

 Lumen : the cavity within a tubular organ. 



Macronucleus : the large nucleus of an inf usorian ; Paramecium, 186 ; 



Vorticella, 190. 

 Madreporic plate : a porous plate through which fluids enter the ambulacral 



system ; starfish, 142 ; sea urchin, 151 ; sea cucumber, 157. 

 Malpighian tubules : the kidney of insects and certain other arthropods ; 



grasshopper, 16 ; caterpillar, 21 ; spider, 27. 

 Mandible : the anterior pair of mouth-parts in arthropods ; grasshopper, 



13 ; beetle, 14 ; wasp, 14 ; caterpillar, 20 ; spider, 24 ; crayfish or 



lobster, 30 ; sow-bug, 47 ; amphipod, 49 ; copepod, 54 ; Daphnia, 56 ; 



nauplius, 59. 



