Pericardial chamber: is the open space 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 canal.
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 circumference or outer margin.
Peripneustic: larvae which have the spiracles absent on middle and posterior thoracic rings, and present on all other body segments.