58 SYNOPTIC KEY 



Pedipalpi. See Palpi. 



Peduncle: A stalk by which a sessile animal or organ is attached. 



Pharynx: The section of the alimentary canal just back of the 

 mouth. 



Photoreceptors: Light percipient organs. 



Placenta: A vascular tissue found in mammals dovetailing into the 

 wall of the uterus on the one side and connected with the 

 embryo on the other thus serving to connect the developing 

 embryo with its mother. 



Polar: Lying at one side of the cell as the North Polar ice field 

 lies on one side of the earth. 



Polyps: One of the feeding individuals of a hydroid or coral colony 

 or a similar form. 



Proboscis: A fleshy structure which extends or is capable of being 

 projected from the body (elephant's proboscis). 



Prolegs: Fleshy appendages found on the abdominal segments 

 of certain larvae particularly those of butterflies and moths. 



Prothorax: The anterior part of the thorax of insects typically 

 bearing the anterior pair of legs. 



Protoplasm: The living matter of which animals and plants are 

 essentially composed. 



Pseudopodia: Irregular projections from cells which may be 

 withdrawn. 



Pupa: A quiescent stage in the life-history of an insect just before 

 the adult condition is reached. 



Radial symmetry: An arrangement of parts such that they 

 radiate around a central axis as in the starfish. 



Rudimentary: Reduced in size from that found in normal develop- 

 ment. 



