Bar | structure crossing central opening. Types; |
Conjunct bar | developed from rim elements (e.g. H. carteri). (Alternative terms optically continuous bar, bar, bridge, see appendix). |
Disjunct bar | formed from elements discrete from the rim (e.g. H. intermedia). (Alternative terms optically discontinuous bar, bridge, bar, see appendix). |
Normally oriented bar | diagonal bar with dextral orientation; i.e. rotated to the right of the long axis in distal view/ anterior end on opposite side to the wing. |
Inversely oriented bar | diagonal bar with sinistral orientation; i.e. rotated to the left of the long axis in distal view/ anterior end on same side as wing. N.B. Use of the terms normal/inverse is a ubiquitously adopted convention based on their relative abundances. |
Blanket | mass of elements forming distal cover. {Theodoridis 1984} |
Flange | rim structure of helicolith (shield is also used by some workers). |
Origin | location of first/shortest elements of flange on the proximal side. |
Proximal plate | inward radiate elements on proximal side of central-area. |
Spur | spike-like expansion of flange near its termination (e.g. H. recta). |
Termination | location of last elements of flange on the distal side. |
Wing | broad expansion of flange near its termination (e.g. H. carteri). |