GLOSSARY 



Plankton, the population of minute plants and animals which 

 live in the surface layers of salt or fresh water. 



Plastron, the under shell of a turtle. 



Pollination, the transference of pollen or male cells to the 

 surface of the pistil in higher flowering plants. 



Posterior, opposite from head end ; hind or tail end. 



Prawn, a large shrimp-like crustacean. 



Predacious, killing other animals for food. 



Pronotum, dorsal region of the prothorax of an insect. 



Pupate, in insects, to undergo a change from larval to adult 

 form. 



Rhizoid, a root-like filament in lower plants. 



Scud, a crustacean of the Order Amphipoda, e. g., Gammarus, 

 Hyalella. 



Sessile, fixed to one place; not on a stalk or stem. 



Setae, bristle-like appendages, in some insects extending back 

 as tails. 



Silt, a fine earthy sediment carried and deposited by water. 



Somite, a segment of the body, especially of worms, crusta- 

 ceans, and insects. 



Spawn, to lay or produce eggs, especially of fishes. 



Spermary, sex organ in which the male or sperm cells develop, 

 as in hydra. 



Spicules, minute calcareous or siHcious bodies forming the 

 skeleton of sponges. 



Spiracles, external openings in the respiratory or tracheal 

 systems of insects and some other arthropods. 



Spore, an asexual reproductive cell capable of producing a 

 new individual without fertilization; a resistant stage 

 enabling small organisms to survive cold or drought. 



Subimago, the nearly mature winged stage of mayflies. 



Swimmeret, abdominal appendage of a crustacean. 



Symbiosis, the association of two species of organisms, in an 

 advantageous partnership. 



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