100 EXPLANATION OF TERMS 



Peripodal cavities: pouches in the embryo in which the rudiments of the 

 future legs and wings are developed. 



Peripodal membrane: the cell layer surrounding the peripodal cavities. 



Peristaltic: that periodic motion of the alimentary canal by means of which 

 the food is forced toward the anal extremity. 



Peristethium: the mesosternum. 



Peristoma -ium: the border of the mouth or oral margin in Diptcra; some- 

 times used as = epistoma ; q. v. 



Peristome: a membranous tissue surrounding the mouth parts at base, and 

 forming the true ventral wall of the head. 



Peritoneal: applied to the membrane surrounding the viscera, trachea, and 

 other internal structures. 



Peritracheal: surrounding the trachea. 



Peritreme: the corneous sclerite surrounding a spiracle. 



Peritrophic membrane: a funnel-like extension of the fore-gut, extending 

 back tube-like, through the chylifk ventricle in some insects. 



Perivisceral: the cavity containing the alimentary canal and its appendages. 



Perlate : beaded : bearing relieved, rounded points in series. 



Perpendicular: upright: at right angles to horizontal. 



Persicinus: the red of peach blossoms. 



Persistent: remaining constantly; always present. 



Personate: gaping; wide open; masked; disguised. 



Pes, Pedes: a foot; feet. 



Petiolar area or Petiolarea: on the metanotum of some Hymenoptcra, the 

 apical or hindmost of the three median cells : = 3d median area ; apical 

 area. 



Petiolata: that series of Hymcnoptera in which there is a slender stalk be- 

 tween the thorax and abdomen : = apocrita. 



Petiolate: supported or placed on a stem or stalk; usually applied in de- 

 scribing venation and the method of attachment of abdomen to thorax. 



Petiole: a stem or stalk: specifically the slender segment between the thorax 

 and abdomen in many Hymenoptera, and some Diptcra. 



Phaeism: applied to a duskiness of butterflies occurring in a limited region. 



Phagocyte: a corpuscle or cell that devours or absorbs noxious organisms 

 and also absorbs the organs of the larval stage in the development to the 

 adult condition. 



Phagocytosis: the destruction or devouring of bacteria or other micro- 

 organisms by phagocytes. 



Phalsenae: a Linnaean term embracing most of the heterocerous Lcpidoptcra. 

 more specifically applied to the Gcometridce. 



Phalanx -ges: a joint or joints of the tarsus: a division of classification of 

 uncertain value ; similar to tribe. 



Phalerated: beaded. 



Phallus: = penis ; q. v. 



Pharyngeal pump: = sucking pump; q. v. 



Pharynx: the back part of the mouth and upper part of the throat: a slight 

 enlargement at the beginning of the oesophagus : in Diptera is sometimes 



