198 INVERTEBRATE ZOOLOGY 



Kidney : an excretory organ ; crayfish or lobster, 34 ; Nereis, 59 ; earthworm, 

 67; mussel, 89; clam, 99; snail, 106; squid, 117; Molgula, 128. 



Labium: the under lip of insects; grasshopper, 10; beetle, 12; wasp, 12; 



caterpillar, 18; centiped, 21. 

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



10; beetle, 12; wasp, 12; caterpillar, 18; crayfish, 24. 

 Lamella: a leaf or plate-like structure, 87, 97. 

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



but which has not yet completed its development ; decapods, 45 ; 



entomostracan, 53; tapeworm, 78; mussel, 91: a holometabolic insect 



between the embryonic and the pupal stages, 18. 

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

 Ligula: the anterior portion of the labium in insects; grasshopper, 11; 



wasp, 12. 



Lithocyst: a marginal sense-organ in campanularian meduste, 159. 

 Liver: a digestive gland; crayfish or lobster, 33; crab, 38; Daphnia, 51; 



mussel, 90 ; clam, 100 ; snail, 109 ; squid, 121 ; starfish, 135. 

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



Bryozoa, 80. 

 Lumen: the cavity within a tubular organ. 



Macronucleus : the large nucleus of an infusorian ; Paramecium, 166; 

 Vorticella, 170. 



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

 system; starfish, 132; sea urchin, 141. 



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

 grasshopper, 13; caterpillar, 19. 



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

 10; beetle, 12; wasp, 12; caterpillar, 18; crayfish or lobster, 24; sow- 

 bug, 41 ; amphipod, 43 ; copepod, 48 ; Daphnia, 50 ; nauplius, 53. 



Mantle: the integumental fold in mollusks which secretes the shell; mus- 

 sel, 84; clam, 94; snail, 103; squid, 114: the body-wall of ascidians 

 beneath the tunic, 126. 



Manubrium: the projection of a medusa's body which bears the mouth, 

 153, 159. 



Maxilla: the paired mouth-parts immediately behind the mandibles in 

 arthropods; grasshopper, 10; beetle, 12; wasp, 12; caterpillar, 18; 

 crayfish or lobster, 24 ; sow-bug, 41 ; amphipod, 43 ; copepod, 48 ; 

 Daphnia, 50. 



