GLOSSARY 



Labrum, the upper lip of insects and of some other arthro- 

 pods. 



Larva, an immature stage in the Hfe of certain animals; in 

 insects, the stage between the egg and the pupa. 



Mandible, the bone of the lower jaw; in crustaceans, the 



third pair of head appendages; in insects, the first or 



upper pair of jaws. 

 Mantle, an outer fold of flesh in many animals; in clams and 



other mollusks it secretes the shell. 

 Maxilla, one of the pair of lower jaws in insects, also present 



in other arthropods. 

 Micropyle, a small opening in the outer covering of an egg 



cell through which a sperm cell may enter. 

 Myriapod, a small arthropod with many pairs of legs, as 



centipedes. 



Node, the point on the stem of a plant from which the leaf 



springs. 

 Nymph, an immature insect which undergoes only partial 



change of form as it matures, e. g., mayflies, grasshoppers. 



Operculum, a homy cover over the opening of the shell of 



some snails; the gill cover of fishes. 

 Ovary, the organ in which egg cells develop. 



Pallia 1 line, scar on the inner surface of clam and mussel shells 

 caused by attachment of muscles of the mantle. 



Palp, a sensory organ near the mouth, often jointed as in 

 insects. 



Parthenogenesis, the development of an egg without fertiliza- 

 tion by a sperm cell. 



Peduncle, a short stalk, as the stem of a flower, or the stalk 

 of a crayfish eye. 



Periostracum, the outer layer of a molluscan shell. 



Petiole, the stem of a leaf. 



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