HETEROGENEITY IN THE DISTRIBUTION OF ELEM ENTS IN THE SHELL OF OSTRACODA - THE EXAMPLE OF LEPTOCYTHERE PSAMMOPHILA

The chemical composition of the shell of Leptocythere psammophila has been determined by means of an electron microprobe. Twelve elements ha ve been analyzed at 30 points that had exactly the same position on 39 valves. Statistical analysis of the results reveals that ail specimen s present a significant anisotropy in the distribution of one or sever al elements. Antero-posterior differences are the more common. Variati ons between inner and outer parts of the shell are less frequent. The elements involved in biological pathways (P, Na, S, Mg, Ca) have a het erogenous distribution. Elements associated with mineral inclusions (A l, Si, Mn, Fe) have a more homogeneous distribution.