. Bulletins of American paleontology. . Figure lU. tttrueture oi' Cineinnatian Mixochoaiiites.—A. Lateral aspect of a SchucJicriuceras internal mold, nomenclature of structure. B. Vertical section through base of Sdiucitcrtoccras obscunun Kliowing sug- gestion of two areas of inllation in the first segment of siphuncle. C. Ver- tical section through apex of Sclmdicrtoccras ef. prolan gal ura (Foerste), partially restored. A. Ascoceroid sejita. B. Basal septum. T. Septum of truncation. L. Lateral angle. S. Siptiuncle. Difficult}' was encountered in the .study of the Cineinnatian Ascoce
. Bulletins of American paleontology. . Figure lU. tttrueture oi' Cineinnatian Mixochoaiiites.—A. Lateral aspect of a SchucJicriuceras internal mold, nomenclature of structure. B. Vertical section through base of Sdiucitcrtoccras obscunun Kliowing sug- gestion of two areas of inllation in the first segment of siphuncle. C. Ver- tical section through apex of Sclmdicrtoccras ef. prolan gal ura (Foerste), partially restored. A. Ascoceroid sejita. B. Basal septum. T. Septum of truncation. L. Lateral angle. S. Siptiuncle. Difficult}' was encountered in the .study of the Cineinnatian Ascoceratidse owing to the close similarity of two genera, Schu- chertoceras and Billimjsites. These genera can be distinguished by the presence of a single nautiloid septum in ScJiuchcrtoceras between the septum of truncation and the first ascoceroid septum. Eillin;jsitcs lacks this structure. For brevity. Miller (1932) pro- posed the basal septum for this septum in Schuchertoceras, a term which has been used in tlie following descriptions. Oc- casionally a ScliHchcrtnccras may show clearly botli the suture of the septum of truncation and the basal septum. More often, only a single nautiloid septum is seen at the base of a shell. It has 'been necessarv to resort to sections to demonstrate whether this. 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 Paleontological Research Institution (Ithaca, N. Y. ); Columbia University. Ithaca, N. Y. , Paleontological Research Institution [etc. ]
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