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Some “laws” of gastropod shell form

Published online by Cambridge University Press:  08 April 2016

Robert M. Linsley*
Affiliation:
Department of Geology, Colgate University, Hamilton, New York 13346

Abstract

Five generalizations derived from the shell form of prosobranch gastropods are developed. (1) A univalve of more than one volution whose aperture lies in a plane that passes through the axis of coiling does not live with the aperture parallel to the substrate. (2) A univalve of more than one volution whose aperture lies in a plane that is tangential to the body whorl does live with the plane of the aperture parallel to the substrate. (3) Gastropods with tangential apertures, when extended, support the shell so that the center of mass of the shell and its contents is over the midline of the cephalopedal mass; this balancing of the shell may be accomplished either by regulatory detorsion, by inclination or by a combination thereof, to keep the center of gravity of the shell as low as possible. (4) Angulations or re-entrants in the gastropod aperture are usually indicative of inhalent or exhalent areas; inhalent areas are directed as far anteriorly as possible. (5) Gastropods having elongated apertures possess only a single gill and develop a water current through the mantle cavity from anterior to posterior along the long axis of the aperture; this axis is subparallel to the anterior-posterior axis of the foot.

These generalizations are then used as the basis for some deductive interpretations of behavioral modes of Paleozoic Gastropoda.

Type
Research Article
Copyright
Copyright © The Paleontological Society 

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References

Literature Cited

Bandel, Klaus. 1976. Observations on spawn, embryonic development and ecology of some Caribbean lower Mesogastropoda. Veliger. 18:249271.Google Scholar
Banks, M. R. and Johnson, J. R. 1957. Maclurites and Girvanella in the Gordon River Limestone (Ordovician) of Tasmania. J. Paleontol. 31:632640.Google Scholar
Knight, J. Brookes. 1952. Primitive fossil gastropods and their bearing on gastropod evolution. Smithson. Misc. Collec. 117:156.Google Scholar
Naef, A. 1913. Studien zur generellen Morphologie der Mollusken. 1. Ergebn. und Fortschr. der Zool. 3:73164.Google Scholar
Raup, David M. 1966. Geometric analysis of shell coiling: general problems. J. Paleontol. 40:11781190.Google Scholar
Raup, David M. and Chamberlain, John A. Jr. 1967. Equations for volume and center of gravity in ammonoid shells. J. Paleontol. 41:566574.Google Scholar
Robertson, Robert and Merrill, Arthur J. 1963. Abnormal dextral hyperstrophy of post-larval Heliacus (Gastropoda:Architectonicidae). Veliger. 6:7679.Google Scholar
Runnegar, Bruce and Jell, Peter A. 1976. Australian Middle Cambrian molluscs and their bearing on early molluscan evolution. Alcheringia. 1:130.Google Scholar
Salter, J. W. 1859. Canadian Organic Remains, Decade 1. 47 pp. Geol. Surv. Can.; Montreal.Google Scholar
Vermeij, Geerat J. 1971. Gastropod evolution and morphological diversity in relation to shell geometry. J. Zool. 163:1523.CrossRefGoogle Scholar
Vermeij, Geerat J. 1973. West Indian molluscan communities in the rocky intertidal zone: a morphological approach. Bull. Mar. Sci. 23:351386.Google Scholar
Vermeij, Geerat J. 1975. Evolution and distribution of left-handed and planispiral coiling in snails. Nature. 254:419420.Google Scholar
Yochelson, Ellis L. 1967. Quo vadis, Bellerophon? pp. 141161 In: Teichert, C. and Yochelson, E. L., eds. Essays in Paleontology and Stratigraphy. University of Kansas Press. Lawrence, Kansas.Google Scholar