Online Dictionary of Invertebrate Zoology: Complete Work - Best Text

Online Dictionary of Invertebrate Zoology 677gression from a copulatory stage to a noncopulatory stagein consecutive molts; subsequent molting leads to a copulatorystage again.periopticon see laminaperioral disc see labial discperiostracal glands (MOLL: Bivalvia) Glands of the mantleedge that secrete the base layer of the periostracum.periostracal groove (MOLL: Bivalvia) The groove between thetentacular fold and the shell fold that houses the periostracalglands.periostracum n. [Gr. peri, around; ostrakon, shell] A thin skinor horny covering on the exterior of the shells of mostMollusca and Brachiopoda. periostracal a.periparturient period That period before, during and aftergiving birth.periphallic organs (ARTHRO: Insecta) Genital processes on theposterior ventral surface of segment 9.peripharyngeal ganglion (BRYO) Prolongation of the cerebralganglion around the oral opening.peripheral a. [Gr. peri, around; pherein, to carry] To or towardthe surface; distant from the center.peripheral nerve net (NEMATA: Adenophorea) A subcuticularneural meshwork that connects the setae and papillae onthe whole body surface of some marine forms.peripheral nervous system Contains all sensory cell bodies(exceptions rare), plus local plexuses in the body wall orviscera, local ganglia of either sensory or motor-and-internuncialcomposition, plus the pheripheral axons making upthe nerves.periplasm n. [Gr. peri, around; plassein, to mold] (ARTHRO:Insecta) A bounding layer formed by cytoplasm in the eggthat lies just beneath the vitelline membrane and completelysurrounds the egg.peripneustic a. [Gr. peri, around; pneustikos, of breathing](ARTHRO: Insecta) Having 9 pairs of functional spiracles;usually a prothoracic pair and 8 abdominal pairs. seepolypneustic.