. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. KUMMEL: POST-TRIASSIC NauTILOID GENERA 369 aspect of the venter is apparent on the third camera. Adorally, the whorls become gradnally more depressed producing the broad venter and narrowly rounded sides. The umbilicus is perforate, measuring approximately 2 mm. in diameter. The suture has very shallow ventral and lateral lobes, and no annular lobe. The siphuncle is in a subventral position. The shell is smooth except for fine growth lines that form a deep tongue-shaped sinus on the b'i^'. 11. Cenoceras txcai
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. KUMMEL: POST-TRIASSIC NauTILOID GENERA 369 aspect of the venter is apparent on the third camera. Adorally, the whorls become gradnally more depressed producing the broad venter and narrowly rounded sides. The umbilicus is perforate, measuring approximately 2 mm. in diameter. The suture has very shallow ventral and lateral lobes, and no annular lobe. The siphuncle is in a subventral position. The shell is smooth except for fine growth lines that form a deep tongue-shaped sinus on the b'i^'. 11. Cenoceras (Sowerby). Diagrammatic cross-section of holotype represented by figures 1, 2, Plate 7. X 1. Hyatt (1883, p. 288) included Nautilus excavatus, d'Orbigny in Endolohus and considered that species to be the latest survivor of that series. However, in 1894 (p. 549) he noted that there were significant differences between the Carboniferous Endolo- hus and the Jurassic species he placed in Digo7iioceras. My own .study of Sowerby's type of Nauiilus excavatus in the (figured here on Plate 7 and Text Figure 11) and Hyatt's type. 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 Harvard University. Museum of Comparative Zoology. Cambridge, Mass. : The Museum
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