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, 187; starfish, 145; sea urchin, 152; sea cucuinber, 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 meduse, 173, 176. 
Liver: a digestive gland; crayfish or lobster, 39; crab, 44; Daphnia, 57; 
mussel, 96; oyster, 101; clam, 107; snail, 119; squid, 181; 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 infusorian; 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. 
