GLOSSARY 91 



organs. The young of insects having incomplete metamor- 

 phosis. 



Oral surface The surface on which the mouth is located. 



Organ A group of cells or tissues which together perform some 

 specific function. 



Pellicle A thin, non-living cell wall covering the body of most 

 Protozoa. 



Plane of symmetry Any plane which passed through an object 

 divides the object into two parts of corresponding size and 

 form. 



Posterior At or toward the hinder end of the body. 

 Prolegs Larval legs, without joints, upon the abdomen of some 

 insect larvae. 



Pseudop odium Temporary protoplasmic process thrust out from 

 membraneless cells. 



Pupa The inactive stage between the larva and adult of insects 

 having a complete metamorphosis. 



Rayed fin A fin, the membrane of which is supported by a se- 

 ries of spines or 'rays.' 

 Right (See definition of left.) 

 Regeneration The power of an organism to replace a lost part. 



Rudimentary Any organ or structure which has not yet reached 



its full development. 

 Segment One of the successively repeated units of the body of a 



jointed animal. 



Seta (pi. setae) : stiff "hairs" or bristles. 



Somite One of the divisions of the body of a segmented animal. 



Spiracles External openings of the respiratory system of in- 

 sects. 



Stalked Extending beyond the margin of the body at the tip of 

 a stalk. 



