Cyrtobaltoceras
Introduction '''''Cyrtobaltoceras''''' is an extinct cephalopod genus known from the upper Lower Ordovician Fort Cassin Formation at Valcour, N.Y. that is included in the Nautiloid family Baltoceratidae
Taxonomy ''Cyrtobaltoceras'' was named by Flower (1964  who then assigned it to the Baltoceratidae which at that time was included in the Ellesmerocerida. The Baltoceratidae, along with included genera, has since been moved to the Orthocerida.
Morphology The genotype, ''Cyrobaltoceras gracile'' Flower, is based on a small, slender, incomplete, 25 mm long  shell with a slight exogastric curvature. Sutures form lobes across the ventral side but go transversely straight across the dorsum. The siphuncle is proportionally large, almost half the shell diameter in width, and lies against the ventral margin.
Retention The holotype of ''Cyrtobaltoceras gracile'', Reusseau Flower's no. 341, is housed in the paleontological collection of the New Mexico Museum of Natural History and Science in Albuquerque, N.M (U.S.A)
''References'' * ''Fossils'' (Smithsonian Handbooks) by David Ward