. The Canadian field-naturalist. Natural history. 102 The Ottawa Naturalist [December type specimen agree with the description of Comarocystites punctatus given by Billings which lead Meek and Worthen to diagram Comarocystites shumardi as having three basal plates. (Geol. Surv. Illinois, o, p. 292). At the time this diagram was prepared a part of the plates of the type specimen of the latter species still were covered by the matrix. Recently the writer removed this matrix and a new diagram has been prepared (Text diagram, No. 4).. Text figure No. 4. Diagram of the thecal plates of the type spe
. The Canadian field-naturalist. Natural history. 102 The Ottawa Naturalist [December type specimen agree with the description of Comarocystites punctatus given by Billings which lead Meek and Worthen to diagram Comarocystites shumardi as having three basal plates. (Geol. Surv. Illinois, o, p. 292). At the time this diagram was prepared a part of the plates of the type specimen of the latter species still were covered by the matrix. Recently the writer removed this matrix and a new diagram has been prepared (Text diagram, No. 4).. Text figure No. 4. Diagram of the thecal plates of the type specimen of Comarocystites shumardi, replacing the diagram published by Meek and Worthen in the report of the Geological Survey of Illinois, volume HI page 292. In order to compare this diagram with that in the Illinois report, the page should be turned so that the part marked anal side forms the bottom of the figure. Additional plates have been ex- posed recently by removing the matrix. The position of the nodular stereom protuberance supporting the left pair of arms is indicated at 1 2. The approximate location of the anal pyramid is indicated by A. The apical part of the theca surrounding the right pair of arms, as far down as the plates bordering on the lower side of the anal opening, is missing. The diagram is not intended to suggest any radiate structure in the arrangement of the thecal plates. It is intended, however, to suggest the presence of more than three plates in the basal series, although the evidence in the particular specimen here diagrammed is Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Ottawa Field-Naturalists' Club. Ottawa
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