Plate P20. Diatoms from rise site: Thalassiosira and Actinocyclus. 1, 4. Thalassiosira lentiginosa. (1) Sample 178-1095A-1H-4, 1-2 cm, (4) Sample 178-1095B-36X-4, 8-10 cm. 2. Thalassiosira lentiginosa var. ovalis (Sample 178-1095A-8H-6, 24-25 cm). 3. Actinocyclus octonarius (Sample 178-1095B-12H-4, 41-42 cm). 5-8. Actinocyclus karstenii. (5) Sample 178-1095B-14X-3, 65-66 cm, (6) Sample 178-1095A-8H-3, 27-28 cm, (7) Sample 178-1095B-8H-2, 74-75 cm, (8) Sample 178-1095B-7H-3, 35-36 cm.