A second species of Biplanispira from the Eocene of Borneo

In 1928, when studying the genus Pellatispira 1), I found some sections of the foraminifer described below in a limestone from S.E. Borneo (no. 1446 B. 414). The foraminifer resembles Pellatispira in many respects, but the distal part of the test shows a different structure, consisting of a double arrangement of median chambers on either side of an equatorial system of pores. Because the material was insufficient I put it aside. Some time afterwards a more intense study was made possible, as another limestone from S.E. Borneo (no. 1408 B. 404) was crowded with the same interesting species. It was, however, not before now that I had the opportunity of finishing this study and to publish the results. I now describe this foraminifer as Biplanispira absurda. In the mean time I met with a foraminifer, which too possesses a single coil of median chambers in the central part of the test, but a double arrangement of median chambers on either side of an equatorial system of pores in the distal part of the test.