GLOSSARY. 107 



Pisiform (L. plsum, a pea ; forma, shape). A small bone on 

 the ulnar side of the carpus in the Mammalia, which is 

 developed in the tendon of the flexor muscle of that side. 



Pis'til (L. pistillum, a pestle). The central, female organ of a 

 flower composed of one or more carpels. 



Pithe'cus (Gr.pithekos, an ape). A genus of the Anthropo- 

 morpha. 



Pitu'itary body (L. pituita, phlegm). A small body on the 

 floor of the skull, and connected with the third ventricle 

 of the brain by the infundibulum. 



Placen'ta (L. a cake). The structure, commonly known as the 

 " after-birth," formed in some mammals from the choriou 

 of the foetus and the decidua of the uterus, and which is 

 cast off in parturition. 



Placoder'mi (Gr. plax, a plate ; derma, skin). A sub-order of 

 Ganoid fishes. 



Pla'coid (Gr. plax, a plate ; eidos, form). Applied to such 

 scales as those of sharks and rays, which consist of 

 irregular bony plates, sometimes armed with spines. 



Plagios'tomi (Gi.plagios, sideways; stoma, stomatos, an opening). 

 A group of Elasmobranch fishes which embraces the 

 sharks and rays, so named because in the sharks the gill- 

 clefts are on the sides of the body. 



Plana'rida (Gr. plane, wandering). A group of Turbellaria. 



Pla'niform (L. pldnum, a level place ; forma, shape). Applied 

 to a joint having nearly flat surfaces ; also termed an 

 arthrbdia. 



Plan'tar (L. plantaris, of or relating to the sole of the foot). 

 Applied to that surface of the foot which corresponds to 

 the palm of the hand. 



Planta'ris (L. relating to the sole of the foot). A muscle 

 passing from the femur to the calcaneum. 



Plan'tigrade (L. planta, the sole of the foot ; gradus, a step). 

 Walking upon the soles of the feet. 



Pla'num tempora'le (L. temporal plane). A flat surface in the 

 skull, forming part of the temporal fossa. 



Plas'ma (Gr. plasma, a thing modelled). Applied to material 

 from which organic structures are formed, and in which 

 they float, as the plasma of blood. 



Plas'mine (Gr. tlasma, a thing modelled). A coagulable sub- 

 stance closely allied to fibrin, obtained from blood plasma. 



Plas'tron (Gr. plastos, formed, moulded). The ventral exo- 

 skeleton of the Chelonia. 



