Online Dictionary of Invertebrate Zoology: Complete Work - Best Text

Online Dictionary of Invertebrate Zoology 203and as such, behave as if they belong to separate species;a rassenkreis.circular plate (ARTHRO: Insecta) In Syrphidae larvae, a weaklysclerotized refractive area on the dorsal inner sector of theposterior spiracular plate; however, in saprophytic forms asunken area at or just above the center of the posteriorspiracular plate.circulation n. [L. circulare, to make round] In higher invertebrateforms, movement of blood within definite channels inthe body; in other forms, movement of blood in the bodycavity fluid.circulatory system The cardiovascular system; the heart andblood vessels. a. Closed system: the blood is confined totubes throughout its entire course. b. Open system: theblood leaves the arteries and circulates through bodyspaces before reentering the heart.circulus n.; pl. circuli [L. circulus, ring] 1. Any ring-like arrangement,i.e., the branching of small blood vessels. 2.(ARTHRO: Insecta) In scale insects, a glandular structurethat discharges its contents internally.circumanal a. [L. circum, around; anus, anus] About or surroundingthe anus.circumapical band (ROTIF) The second division of the coronathat encircles the margin of the head. see buccal field.circumboreal a. [L. circum, around; Gr. boreas, north wind]Pertaining to the north, i.e., distribution around the borealregion.circumcapitular furrow (ARTHRO: Chelicerata) In Acari, thefurrow around the base of the gnathosoma.circumcolumellar a. [L. circum, around; columella, pillar]Surrounding a columella.circumenteric ring (NEMATA) A commissural nerve ring thatencircles the esophagus (pharynx).circumesophageal, circumoesophageal a. [L. circum,around; Gr. oisophagos, gullet] Structures or organs encirclingthe esophagus.circumesophageal commissure The major commissure of