| Conjunct | formed from crystal-units of the rim structure. E.g. Gephyrocapsa (bridge and grill), Helicosphaera sellii (bar), Kamptnerius (plate), Watznaueria biporta (bar). (Alternative term optically continuous structure, see appendix). {Young 1992a} |
| Disjunct | formed from crystal-units discrete from the rim structure. E.g. Arkhangelskiella (plate), Coccolithus pelagicus (bar), Helicosphaera seminulum (bar), Watznaueria britannica (bar). (Alternative term optically discontinuous structure, see appendix). {Young 1992a} |
| Simple | bar, or similar, appearing to be formed of a single unit |
| Split perpendicular to length | bar, or similar, appearing to be formed of two units, meeting in the middle |
| Divided longitudinally | bar, or similar, appearing to be formed of two parallel sub-bars separated by an extinction line |
| Complex | bar, or similar, with more complicated structure, appearing to be formed of numerous sub-units |
| Basal | occurring on the proximal surface. |
| Elevated | occurring above the proximal surface. |
| Vaulted | cone-shaped, rising from the rim toward the centre. |
| Planar | flat, not vaulted. |
| Transverse | parallel with short axis of (elliptical) coccolith. |
| Longitudinal | parallel with long axis of (elliptical) coccolith. |
| Diagonal | inclined relative to axes. We reccomend that the angle should be measured from the transverse direction, hence: Low angle near to transverse direction; High angle near to longitudinal direction. NB Some authors use the opposite convention, i.e. measure angle from longitudinal direction, so care needs to be taken when using the literature. |
| Dextral/sinistral | inclined to the right/left of the long-axis as seen in distal view. N.B. As with element obliquity the terms dextral/sinistral are preferred for describing orientations which appear different in proximal and distal view. |
| Relative width | width of central-area relative to rim width: Wide central-area width >2x rim width; Normal central-area width 1-2x rim width; Narrow central-area width <1x rim width. |
| Arm | part of crossbar, bridge or cross running from centre of coccolith to edge of central-area. (alternative terms limb, spoke, see appendix). |
| Bar | any elongate central-area structure. N.B. This is a general term. When it is useful to be more specific terms such as longitudinal bar, cross-bar, and arm can be used. (Alternative term jugum, see appendix). |
| Blanket | covering of small elements on distal side of central-area (e.g. Helicosphaera, Coccolithus). |
| Bridge | elevated bar spanning the central-area (e.g. Gephyrocapsa). |
| Cross-bar | bar spanning the central-area. |
| Cross | pair of cross-bars meeting in centre. Axial cross (abb. +), cross-bars longitudinal and transverse. Diagonal cross (abb. X) cross-bars diagonal - may be symmetrical or asymmetrical relative to the axes. Offset cross cross with an offset between the arms of one, or both, of the crossbars (e.g. Chiasmolithus). |
| Foot | broadening of bar as it meets the rim (e.g. Cruciplacolithus tenuis). |
| Lateral bar | bar running from rim to a cross bar (e.g. Retecapsa). |
| Central opening | opening at centre of coccolith, may be spanned by bars or other central-area structures, but not by a continuous structure such as a grill or plate. |
| Closed central-area | central-area without a central opening. |
| Grill | system of bars closing central-area (e.g. Emiliania). |
| Net | mesh-like structure closing central-area (e.g. Reticulofenestra, Cribrosphaerella). (Alternative term cribrate central-area, see appendix). |
| Open central-area | central-area without any structures. |
| Plate | continuous or nearly continuous structure closing central-area. |
| Perforated plate | plate with perforations (e.g. Arkhangelskiella). |
| Calyx | flaring structure at tip of process (e.g. Podorhabdus, Papposphaera). |
| Boss | low process, height similar to or less than width (alternative term knob, see appendix). |
| Process | general term for any structure rising from the central-area. |
| Protrusion | broad low process, with height similar to width, and width near that of entire central-area. Types: Conical cone-shaped protrusion (e.g. Acanthoica); Sacculiform sac-like protrusion with more or less rounded upper part (e.g. Algirosphaera). (N.B. labiatiform has been used for the elongate double-lipped sacculiform protrusions, see appendix). |
| Spine | elongated process, height greater than width. (Alternative term column, see appendix). Types: Styliform {Halldal and Markali 1955} - spine tapers toward the distal end; Claviform {Halldal and Markali 1955} - spine has blunt end, without calyx. (N.B. helatoform has been used for nail-shaped processes, see appendix); Calicate - spine is surmounted by a calyx. Salpingiform {Braarud et al. 1955a, 1955b} - spine (or protrusion) trumpet-shaped (e.g. Discosphaera). |
| Stem | part of process below calyx. |
| Cavity | wide opening within process (e.g. Podorhabdus grassei, Algirosphaera robusta). |
| Canal | narrow opening running along length of process. |
| Proximal pore | opening of canal, on proximal side of central-area. |
