Pelotons: the b.a.l.l.s of fine tracheae in larvae, developed to supply the adult organism.

Pelottae: =arolia: q.v.

Peltate: shield- or target-shaped.

Penal claspers: in Proctytripidae. lateral fringed processes of the male genitalia.

Penal sheath: the h.o.r.n.y outer covering of the p.e.n.i.s.

Pencil: a little, elongated brush of hair: in Diptera, applied to a group of sensory hairs on the flagellum of the antenna.

Pendent: hanging down.

Pendulous: drooping: hanging free, attached to one end only.

Penes: open, slit-like structures of the seminal vesicles to the outer surface in Euplectoptera.

Penicillate: with a long, flexible brush or pencil of hair: often at the end of a thin stalk.

Penicilli: a pair of small style or cerci-like pieces on the tip of the 8th dorsal segment of abdomen of various male Hymenoptera.

Penicilliform: pencil-like or shaped.

Penicillum: a pencil or brush of long hair attached at the end of a stalk as long as the brush, and folded in a lateral groove in some male moths.

p.e.n.i.s: the flexible, membranous, intromittent organ of the male.

Pennaceous: = pennate.

Fermate: feathered or bearing feather-like processes.

Penniform: feather-like in form.

Pentagon -um: a five-sided figure with five equal or unequal angles.

Pentamera: Coleoptera with 5-jointed tarsi.

Pentamerous: species having five-jointed tarsi.

Penultimate: next to the last.

Peptone: a soluble proteid compound produced by the digestion of alb.u.mmenoid food substances.

Per-: as a prefix, means very: extremely: through.

Percipient: with the power of perceiving.

Percurrent: running through the entire length.

Pereion: the prothorax.

Pereipoda: the second and third pair of thoracic legs of larvae, and the 2d pair in adults.

Perfoliate: divided into leaf-like plates: applied to antennae with disc-like expansions connected by a stalk pa.s.sing nearly through their centres: also to any part possessing a well-developed leaf-like or plate-like expansion.

Pergamenous: thin, partly transparent: resembling parchment.

Peri-: round about.

Periopticon: a complex nerve structure back of the basilar membrane of the eye.

Pericardial: around, or belonging to the heart.

Pericardial cavity: the s.p.a.ce between the diaphragm and dorsal body wall, which contains the heart.

Pericardial cells: specialized cells, which lie along both sides of the heart, and whose function it is to purify the blood.

Pericardial chamber: is the open s.p.a.ce around the heart or dorsal vessel.

Pericardial diaphragm: a delicate membranous tissue attached to the ventral surface of the heart and laterally to the body wall := dorsal diaphragm wings of the heart.

Peri-intestinal: that part of the body cavity around the alimentary ca.n.a.l.

Peri-neural: situated around a nerve: the body cavity immediately surrounding the nervous system.

Periodical: recurring at regular intervals.

Periopticon: third ganglionic swelling of optic tract: see opticon.

Peripheral: referring to the outer margin.

Peripheria: the entire outline of the body.

Periphery: the circ.u.mference or outer margin.

Peripneustic: larvae which have the spiracles absent on middle and posterior thoracic rings, and present on all other body segments.

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 ca.n.a.l by means of which the food is forced toward the a.n.a.l extremity.

Peristethium: the meso-sternum.

Peristoma -ium: the border of the mouth or oral margin in Diptera; sometimes used as := epistoma: q.v.

Peristome: a membranous tissue surrounding the mouth parts at base, and forming the true ventral wall of the head.