682 



COLLEGE ZOOLOGY 



times are used in seizing prey, as in scorpi- 

 ons. 



Pe'do-gen"e-sis (Gr. pais, child; genesis, 

 origin). Reproduction by larvae. 



Pe-lag'ic (L. pelagicus, from pelagus, sea). Of 

 or inhabiting the open water, away from 

 shore, as in the ocean. 



Pel'li-cle (L. pellicula, small skin). The thin 

 protective layer on the surface of some 

 protozoans, for example, the paramecium. 



Pervic gir'dle (L. pelvis, a basin). The group 

 of bones to which the bones of the hindlimb 

 are attached, connecting the hindlimb to the 

 axial skeleton in the vertebrates. 



Pe'nis (L. ) The male organ of copulation for 

 conveying sperms to the genital tract of the 

 female. 



Pen'ta-dac"tyl (Gr. pente, five; daktylos, fin- 

 ger). Having 5 fingers, toes, or digits. 



Pep'sin (Gr. pepsis, a cooking, digesting). An 

 enzyme concerned with protein digestion in 

 animals. 



Per-ei'o-pods (Gr. peraioun, to con\'ey; pous, 

 foot). The walking legs of a crayfish or 

 related crustacean. 



Per'i-car"di-um (Gr. peri, around; cardia, 

 heart). The closed membranous sac sur- 

 rounding the heart. The part in contact with 

 the heart is the visceral pericardium; the 

 other, the parietal pericardium. 



Per'i-os''te-um (Gr. peri, around; osteon, 

 bone). Connective tissue sheath that covers 

 the surface of a bone. 



Pe-riph'er-al (Gr. periphereia, from peri, 

 around; pherein, to bear, carr\). Of, belon- 

 ing to, or situated at the surface. 



Per'i-sarc (Gr. peri, around; sarx, flesh). The 

 outer transparent membrane that encloses 

 the inner coenosarc of a hydroid. 



Per'i-star'sis (Gr. peri, around; stalsis, con- 

 striction ) . A type of smooth muscle contrac- 

 tion in which a wave of contraction follows 

 a wave of relaxation, passing along a hollow 

 organ, especially the digestive tract. 



Per'i-stome (Gr. peri, around; stoma, mouth). 

 The region around the mouth of a radially 

 symmetrical animal, such as the hydra. 



Per'i-to-ne"um (Gr. peri, around; tenein, to 

 stretch). The thin membrane (mesoderm) 

 that lines the coelom and covers the viscera 

 in many animals, especially the verte- 

 brates. 



Phag'o-cyte (Gr. phagein, to eat; kytos, cell). 

 A type of white blood cell that engulfs and 

 digests bacteria and other foreign materials. 



Pha-lan'ges (Gr. phalanx, long line of battle). 

 Bones of the digits. Singular, phalanx. 



Pha-ryn'ge-al cleft (Gr. pharynx, gullet. A.S. 

 cleofian, to split). Slit in the wall of the 

 pharynx; same as gill slit, gill cleft, or bran- 

 chial slit. 



Phar'ynx (Gr. pharynx, gullet). That anterior 

 portion of the digesti\e tract between the 

 mouth cavity and the esophagus, often mus- 

 cular; and the gill region of many aquatic 

 vertebrates; sometimes with teeth in in- 

 vertebrates. 



Phe'no-type (Gr. phaino, show; typto, strike). 

 The expressed traits of an individual, as 

 contrasted with its genetic constitution or 

 genotype. The sum total of the realized 

 characteristics of an individual; in other 

 words, the structural and physiologic traits 

 of an individual. Sometimes incorrectly de- 

 fined as external appearance of an individual 

 which would exclude physiologic traits such 

 as blood groups. Compare with Genotype. 



Pho'to-syn"the-sis (Gr. phos, light; synthesis, 

 putting together). The formation of glucose 

 from carbon dioxide and water by chlorophyl 

 in the presence of light. 



Pho-tot'ro-pism (Gr. phos, light; Gr. trepein, 

 to turn ) . The behavior response of an animal 

 to light stimuli. 



Phy-log'e-ny (Gr. phylon, race, branch; geny, 

 become). Ancestral or evolutionary history 

 of a species or higher group. 



Phy'lum (Gr. phylon, tribe). Any one of the 

 main taxonomic divisions into which the 

 animal kingdom is divided. 



Phys'i-oF'o-gy (Gr. physis, nature; logos, 

 study). The science dealing with the func- 

 tions in organisms. 



Pi'a ma'ter (L., tender mother). The thin, in- 

 nermost, membranous covering of the brain 

 and spinal cord. 



Pig'ment (L. pingere, to paint). Coloring 

 matter. 



Pin'e-al (L. pinea, pine cone). A structure lo- 

 cated on the roof of the brain of vertebrate 

 animals; phylogenetically associated with a 

 median eye. 



Pi-tu"i-tary bod'y (L. pituita, phlegm. A.S. 

 bodig). An endocrine gland located on the 



