Acantharia
Acknowledgments

This work is based partly on an earlier manuscript version prepared by Anthony Michaels, which in turn was derived from a summary written by C. Febvre, J. Febvre and A. Michaels. We are indebted to A. Michaels for putting this initial draft and other pertinent materials at our disposal, as well as to John Lee for providing unpublished graphic materials for consultation purposes. The assistance of Georges Merinfeld for the identification of several of the SEM images is greatly appreciated. Michiko Matsubara provided efficient technical assistance. This work was partly financed by grants from the University of Buenos Aires (UBA EX-040), from the Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina (CONICET PID-BID 0366), and from the Agencia Nacional de Promoción Científica y Tecnológica, Argentina (PMT-PICT0395).