GLOSSARY. 169 



^P elvis The bony arch to which the hind limbs of the Vertebrate 



are attached. 

 Pericardium (Gr. peri, around; kardia, the heart) The membrane 



that surrounds the heart. 



Perigastric (Gr. peri; gaster, the stomach) The space which sur- 

 rounds the stomach and other internal organs. 

 Perivisceral (Gr. peri; Lat. viscera, the internal organs) The 



space surrounding the viscera. 

 Phalanges (Gr. phalanx, a row) The bones which compose the 



digits of the higher Verlebrata. 

 - Pharynx The upper part of the gullet. 

 Phragmacone (Gr. pliragma, a partition; konos, a cone) That 



part of the internal shell of a belemnite which is divided 



into chambers by partitions. 

 Pisces (Lat. piscis, a fish) A class of Vertebrata. 

 Placenta (Lat. a cake) An organ containing a network of blood- 

 vessels, by which the young of the higher mammals receive 



nourishment from the mother before birth. 

 Place-id (Gr. plax, a plate ; eidos, form) Applied to the scales of 



sharks and rays, which are in the form of irregular bony 



plates, sometimes armed with spines. 

 Planarida (Gr. plane, wandering) A group of Turbellaria. 

 Pleura (Gr. the side) The membrane which surrounds the lungs 



of the higher Vertebrata. 

 Pneumatic (Gr. pneuma, air) Containing air. 

 Polycystina (Gr. polus, many ; kustis, a bladder) A group of 



Protozoa with minute perforated siliceous shells. 

 Polygastrica (Gr. polus ; gaster, stomach) The name given by 



Ehrenberg to the Infusoria. 



Polypary The chitinous covering of the compound Hydrozoa. 

 Polype (Gr. polus, many ; pous, foot) A single individual in the 



Actinozoa. 



Polypide One of the zooids in the Polyzoa. 

 Polypite One of the zooids in the Hydrozoa. 

 Polyzoa (Gr. polus, many ; zb'on, an animal) A class of Mollus- 



coida called also Bryozoa. 

 Polyzoarium The polypidum, or chitinous covering of the 



Hydrozoa. 

 Prsemolars The permanent molars which succeed the molars of 



the milk set of teeth ; the bicuspid teeth, 

 t^roccelus (Gr. pro, front; koilos, hollow) Applied to vertebrae 



which are hollow in front. 

 Protoplasm (Gr. protos, first ; plasso, I mould) The primitive 



basis of all organic tissues, sometimes used as a synonym for 



sarcode. 



Protozoa (Gr. protos; zoon, an animal) The lowest of the sub- 

 kingdoms. 



