Plate P4. Triquetrorhabdulus, Calcispheres, Discoasteraceae. Taxonomic organization and concepts are generally comparable to those of Young and Bown (1997) and Young (1998). Images with black background are cross-polarized light images; those with light backgrounds are phase-contrast images. 1–6. Amaurolithus primus; (1, 2) Sample 198-1208A-26X-CC, (3, 4) Sample 198-1208A-21X-CC, (5, 6) Sample 198-1208A-24X-CC. 7–9. Ceratolithus cristatus; (7, 8) Sample 198-1208A-19H-CC, (9) Sample 198-1208A-1H-CC. 10, 11. Ceratolithus rugosus; (10) Sample 198-1208A-19H-CC, (11) Sample 198-1208A-14H-CC. 12, 15–17. Calcisphere (12) Sample 198-1208A-1H-CC, (15) Sample 198-1208A-18H-CC, (16, 17) Sample 198-1208A-4H-CC. 13, 14. Triquetrorhabdulus rugosus (Sample 198-1208A-28X-CC). 18–20, 24, 25. Discoaster deflandrei; (18) Sample 198-1208A-32X-CC, (19, 20) Sample 198-1208A-34X-CC, (24, 25) Sample 198-1208A-35X-3, 149 cm. 21. Discoaster exilis (Sample 198-1208A-30X-4). 22, 23. Discoaster petaliformis (Sample 198-1208A-34X-5). 26, 27. Discoaster druggii (Sample 198-1208A-35X-3, 149 cm). 28–31. Discoaster exilis (Sample 198-1208A-32X-CC).