Zygodiscus adamas Bramlette & Sullivan, 1961
This elliptical discolith is constructed by a dextrally arranged outer wall, a tangentially arranged wide inner wall, and a central area spanned by a disjunct bar of varying width and orientation.
The narrow outer wall remains in constant extinction, whilst the inner wall exhibits first-order white to yellow interference colours with dextrogyre inclined extinction lines and length-fast (−) elongation on the distal side.
Bramlette, M. N. & Sullivan, F. R. 1961, Coccolithophorids and related nannoplankton of the Early Tertiary in California. Micropaleontology 7(2): 129-188.