virgatotome

English

Etymology

Ultimately from Latin virga.

Adjective

virgatotome

1. (malacology, of the ribs on a shell) Having multiple secondary ribs which branch off successively in front of each primary rib (resulting in a shape like ᚠ), like the ribs of Zaraiskites ammonites.
   • 1967, J. C. W. Cope, The Palaeontology and Stratigraphy of the Lower Part of the Upper Kimmeridge Clay of Dorset:

     [...] gyrate furcation, and often a tendency to become fasciculate or virgatotome; secondary ribs obsolescent in some [...] polygyrate ribs and intercalatory secondaries. Microconchs 100-112 mm. in diameter with following rib densities […]

   • 1977, Acta geologica polonica:

     ... polygyrate or bidichotomous to fasciculate (rarely virgatotome) ribs, more loosely spaced and coarser. External whorls of macroconch forms with dichotomous to polygyrate ribs […]