The study of opened specimens of Millettia species confirms the presence of septula subdividing the individual chambers. Toothplates are present between the individual septular foramina, and the chamber foramen. Polished and etched sections show the test to be bilamellar, but secondary lamination is absent. The toothplates are monolamellar and made up of inner lining, each one continuous with the septula which are formed by doubled-up inner lining. Laterally, the internal chamber walls are covered by a web-like coating of supplementary inner lining, continuous with the septula. X-ray diffraction shows the genus to be calcific. The genus is revised to include M. tessellata, M. limbata and the newly described M. ipsithillae and M. polyxenae. The monotypic Millettiidae are considered incertae sedis within the Rotaliina.
- Received March 1, 1991.
- Accepted October 1, 1991.
- © 1992 The Micropalaeontological Society