planospiral

planospiral

[¦plā·nō′spī·rəl]
(invertebrate zoology)
Having the shell coiled in one plane, used particularly of foraminiferans and mollusks.
References in periodicals archive ?
71-73) up to 15 mm, planospiral, about 3.5 loosely coiled whorls that are angulated above and below, spire deep, depressed on both sides; sutures shallow; growth lines conspicuous, crowded; aperture broadly lunate, sharply shouldered below and extending beyond plane of spire, inflated and rugose in mature specimens (Harmen & Berg 1971); subfossils well-preserved, but lack periostracum.
74, 75) up to 15 mm, sinistral, planospiral, with 4.5 tightly coiled whorls; sutures deep; growth lines conspicuous, evenly spaced, aperture broadly lunate, inflated on mature specimens (Harmen & Berg 1971); subfossils well-preserved, lack periostracum.
76, 77) up to 7 mm, but mostly less than 4 mm, planospiral, 3.5 whorls; spire depressed; sutures deeply impressed; aperture broadly lunate, deflected downward (Harmen & Berg 1971); subfossils well-preserved, lack periostracum.