GLOSSARY 399 



Prototheria iino' to the' ri a). A suliclass of Mammalia, Including the egg-laying 

 mammals such as the duckbill Ornithorliyiichus and the spiny ant-eater Echidna. 



Protozoa (pro' to zo' a). Onc-cellcd animals. The phylum comprising the ono-celled 

 animals, including colonial forms in which the cells of the colony are, at least poten- 

 tially, all alike. 



Protozoology (pro' to zo oV oji). The zoology of the Protozoa. 



Protylopus (pro ti' lo pus). The earliest known ancestor of the camels. 



Proventricixlus (pro' ven trik' u lus). The first division of the stomach of a bird. 



Pseudacris (su dak' ris). A genus of frogs. 



Pseudopodium (su' do po' di um) (pi., pseudopodia). A blunt finger-like projection 

 thrust out by Amoeba and other rhizopods. 



Psychozoic (si' ko zo' ik). Pertaining to the most recent geological time, that in 

 which man developed as an intelligent being; the time following the Cenozoic era. 

 Ptyalin (li' a lin). The amylolitic enzyme of the saliva. 



Pubis (pu' his) (pi., pubes, pu' beez) The anterior one of two ventrally placed bones 

 in the pelvic girdle of vertebrate animals above the fishes. 



Pulmonary circulation (puV mo na ri ser' ku la' shun). The circulation of the blood 

 through the lungs, as distinguished from th^t through the body in general 

 (systemic). 



Pulmonata (puV mo na' ta). An order of air-breathing snails and slugs. 



Pulsating vacuole (puV sa ting vak' u ole). Same as contractile vacuole. 



FHipa (pu' pa). A quiescent stage in the development of an insect, just before the 



adult condition is reached. 

 Purkinje, Jan Evangelista (jyoor keen' ya). Bohemian physiologist in the University 



of Prague, 1787-1869. 

 Pylorus (pi lo' rus). The opening from the stomach to the intestine. 

 Pyrenoid (pi re' noid). A small protein bodj^ found enclosed in some cells. 

 Pyrosoma (pi' ro so' ma). A colonial tunicate in which the colony is cylindrical in form„ 



Quadrate (kwod' rate). One of the bones of the skull; in birds and reptiles and bony 



fishes, the bone from which the lower jaw is suspended. 

 Quaternary (kwa ier' na ri). A division of Cenozoic time later than the Tertiary, 



Race (rase). A group of individuals having certain characteristics in common because 

 of common ancestry. 



Radial canal (ra' di al ka nal'). One of four tubes extending from the middle to the 

 margin of a medusa. 



Radial symmetry (ra' di al sim' me tri). An arrangement of the parts of an object 

 or organism such that it is capable of being divided into halves that are mirrored 

 images of one another, by two or more planes all of which pass through a common 

 longitudinal axis. 



Radiating canal (ra' di at ing ka nal') One of a series of collecting channels surround- 

 ing the pulsating vacuoles of Paramecium and similar Protozoa. 



Radio-ulna (ra' di o uV na). The fused radius and ulna of frogs and toads. 



Radius (ra' di us). The bone of the lower arm located on the thumb side in Amphibia 

 and the higher vertebrates. 



Rana (ra' na). A genus of frogs. R. pipiens (pip' i enz), the common leopard frog. 



