. Bulletins of American paleontology. 48 Bulletin 150 194. Fig. 8. Ectosiphuncle of Hcmichoanclla canningi. Family Eothinoceratidae Ulrich, Foerste, Miller and Unklesbay, 1944 The family Eothinoceratidae was erected by Ulrich, Foerste, Miller and Unklesbay (1944) for the reception of a single new genus, Eothinoceras. The walls of the siphuncular segments of Eothinoceras were shown to be greatly thickened and V-shaped in longitudinal section, the apex of the V pointing inwards. Eothinoceras ameri- canum, the only species of the genus, was described from a few poorly preserved fragments which ha
. Bulletins of American paleontology. 48 Bulletin 150 194. Fig. 8. Ectosiphuncle of Hcmichoanclla canningi. Family Eothinoceratidae Ulrich, Foerste, Miller and Unklesbay, 1944 The family Eothinoceratidae was erected by Ulrich, Foerste, Miller and Unklesbay (1944) for the reception of a single new genus, Eothinoceras. The walls of the siphuncular segments of Eothinoceras were shown to be greatly thickened and V-shaped in longitudinal section, the apex of the V pointing inwards. Eothinoceras ameri- canum, the only species of the genus, was described from a few poorly preserved fragments which had been ground and polished in planes of random orientation. The only forms referable to the family appeared to have straight breviconic conchs, with short camerae, and a large ventral siphuncle. They all came from the Middle Canadian Rochdale limestone of New York. The family Cyrtocerinidae was established by Flower in 1946 with Cyrtocerina Billings as the only genus. Flower was of the opin- ion that Eothinoceras agreed with Cyrtocerina and with no other genus in the structure of the siphuncle, having achoanitic septal necks and highly inflated connecting rings. In a later paper Flower and Kummel (1950) included Eothinoceras with Cyrtocerina in the family Cyrtocerinidae. They considered Eothinoceras to be endo- gastric, with compressed shell and vestigial septal necks. The structure of the connecting rings of the Australian species of Eothinoceras is almost identical with the connecting ring struc-. 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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