Proximal | directed toward centre of coccosphere/cell. On nannofossils this is usually assumed to be the concave side, but cannot always be determined. |
Distal | directed toward outer surface of coccosphere/cell. |
Horizontal | perpendicular to proximo-distal direction. |
Vertical | proximo-distal direction. |
Internal/inner/inward | toward centre of coccolith. |
External/outer/outward | away from centre of coccolith. |
Longitudinal | direction parallel to long axis of an elliptical / elongated coccolith. |
Transverse | direction parallel to short axis of an elliptical / elongated coccolith. |
End | edge of coccolith parallel to short axis. |
Side | edge of coccolith parallel to long axis. |
Length/width/height | maximum dimensions of coccoliths in the longitudinal, transverse and vertical directions respectively. |
Central-area | Inner part of coccolith, enclosed by the rim. Usually characterised by less regularly cyclical elements than the rim and by inward element growth. May be entirely closed, or include a central opening. N.B. We recommend hyphenating central-area since it has a special meaning. |
Rim | Outer part of coccolith, usually characterised by regular cycles, some vertically directed structures and outward element growth (alternative term marginal area, see appendix). N.B. Use of this term was agreed after considerable discussion at the workshops. |
Murolith | rim elevated but without well developed shields (e.g. Zeugrhabdotus, Pontosphaera). (Discolith has been used in this sense, see appendix). {Young 1992a, from Latin murus wall} |
Placolith | rim has two, or more, well developed shields (e.g. Coccolithus, Emiliania, Watznaueria). {Lohmann 1902} |
Planolith | rim not significatly elevated (e.g. Rhabdosphaera, Discoaster). {Young 1992a, from Latin planus flat} |
Axial Ratio (abb. AR) | ratio of length to width. Suggested descriptive terms, for elliptical coccoliths, are: Circular ; Sub-circular; Broadly elliptical; Normally elliptical; Strongly elliptical.. |
Asymmetrical | without bilateral symmetry, due to a wing or similar structure. |
Elliptical | continuously curved with two axes of symmetry. Close to, but not necessarily an exact, mathematical ellipse (alternative terms oval, ovoid, see appendix). |
Irregularly elliptical | with an approximately elliptical shape but departing noticeably from regular form. |
Lenticular | symmetrical form intermediate between a rhombus and ellipse, i.e. with pointed ends (e.g. Syracosphaera prolongata, Stradnerlithus). |
Oblong | symmetrical form intermediate between a rectangle and ellipse, i.e. with curved ends but sub-parallel sides (e.g. Calciopappus caudatus, Ellipsolithus macellus). N.B. This is recommended botanical use (Stearn 1983). |
Polygonal | with straight sides (triangular, pentagonal etc., e.g. scapholiths, Corollithion). (alternative term geometric, see appendix). |
Reniform | concavo-convex, kidney-shaped (e.g. Nephrolithus). |
Ring-shaped | circular or elliptical with narrow rim and open central-area (e.g. Cricosphaera, Manivitella). |
Wing | local extension of rim (e.g. Helicosphaera, Kamptnerius). |
Caneolith* | Syracosphaeraceae, endothecal coccolith. (N.B. The terms complete/incomplete caneoliths have been used, see appendix). {Braarud et al. 1955a, 1955b} |
Cricolith* | Pleurochrysidaceae, placolith with narrow rim and open central-area . {Braarud et al. 1955a, 1955b} |
Cyrtolith* | Syracosphaeraceae, exothecal coccolith. {Braarud et al. 1955a, 1955b} |
Discolith* | Pontosphaeraceae, murolith without flanges. {Huxley 1868} |
Helicolith | Helicosphaeraceae, coccoliths with helical flange. |
Lopadolith | high rimmed equatorial murolith of Scyphosphaera. {Lohmann 1902} |
Osteolith | whorl coccoliths of Ophiaster. {Halldal and Markali 1955} |
Pappolith* | Papposphaeraceae. |
Podorhabdid coccolith | Podorhabdaceae. |
Protolith | Stephanolithaceae, Parhabdolithaceae (cf. Bown 1987). |
Rhabdolith | Rhabdosphaeraceae, planoliths +/- spines. {Schmidt 1870} |
Scapholith | Calciosolenia, Anoplosolenia. (Alternative term rhombolith). {Deflandre and Fert 1954} |
Tremalith* | Hymenomonadaceae, vase-shaped murolith. {Lohmann 1913} |
Reticulofenestrid coccolith | Reticulofenestra and descendants. {Young 1989} |
Coccolithid placolith | Coccolithaceae. {Jordan et al. 1995} |