. Bulletin of the Natural Histort Museum. Geology series. The shell material on most specimens is thin, somewhat laminar in appearance and takes the buff colour of the matrix. In order to establish the nature of this shell, slivers from two specimens were studied by qualitative energy dispersive x-ray microanalysis using scanning electron microscopy in the Department of Mineralogy, The Natural History Museum, London. The results show a strong dominance of calcium, with no magnesium or phosphorus present (Fig. 9). The mineralogy indicates dominance of calcium carbonate (lacking magnesium) and t
. Bulletin of the Natural Histort Museum. Geology series. The shell material on most specimens is thin, somewhat laminar in appearance and takes the buff colour of the matrix. In order to establish the nature of this shell, slivers from two specimens were studied by qualitative energy dispersive x-ray microanalysis using scanning electron microscopy in the Department of Mineralogy, The Natural History Museum, London. The results show a strong dominance of calcium, with no magnesium or phosphorus present (Fig. 9). The mineralogy indicates dominance of calcium carbonate (lacking magnesium) and the lack of phosphate precludes the presence of apatite. The shell is not calcophosphatic so articulate brachiopods could have been the animals which secreted this shell material. It seemed unlikely that more material would become available, so it was important to preserve what we had. For this reason only two specimens were sectioned in an attempt to determine what internal structures were present. However, some internal details could also be seen on broken surfaces which cut across specimens while the rock was being broken, as well as on naturally weathered surfaces cutting across the partial interiors of two specimens. Careful examination of all specimens under a binocular microscope, commonly making drawings using a Wild drawing arm, gradually allowed the recognition of some consistent features on several specimens, which provided a form of orientation. The recognition of the same structures in different views and sections has allowed a general picture of the morphology of these specimens to be built up. Portions of shell from near the apex and the distal regions of the cone, and from the supposed dorsal valve have been studied uncoated in the environmental chamber of an ISI ABT55 scanning electron microscope and coated using a S2500 Hitachi machine, both in The Natural History Please note that these images are extracted from scanned page images that may have been d
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