Cretarhabdus multicavus Bukry, 1969
From the Greek ataktos, meaning “irregular” or “without order”, and lithos, meaning “stone”, referring to the irregular arrangement of the pores.
The slightly deformed placolith comprises a cretarhabdid pelaga sloping towards the central area, composed of inclined segments that are weakly clockwise-imbricated in most specimens, and a distally arched central area with an indistinct axial cross whose longer arms curve adjacent to the pelaga. Each quadrant between the cross arms contains two to three randomly arranged irregular pores. No distal process was observed.
The placolith generally displays first-order, pale greyish-white interference colours; however, it becomes dimmer towards the periphery, where only the inner layer of the distal shield is developed. In plan view under crossed polars, the outer layer of the distal shield exhibits inclined extinction and length-fast (–) elongation.
Bukry, D. 1969. Upper Cretaceous coccoliths from Texas and Europe. University of Kansas Paleontological Contributions, Articles 51 (Protista 2): 1-79.