Hall, James, 1811-1898 / Geological survey of Wisconsin, 1859-1863. Palaeontology. Part third
Plate XVI, pp. [unnumbered]-Plate XVI PDF (670.7 KB)
PLATE XVI. TROCHOCERAS NOTUM, HALL. Page 403. FIG. 1. Dorsal view of a fragment of this species. " 2. A septum showing its convexity and the position of the siphuncle. CYRT1'OCERAS RIGID ux, HALL. Page 408. FIG. 3. Lateral view of the outer portion of the cast, showing the curvature of the shell and the character of the undulating ridges. c 4. Dorsal view of the same. " 5. Transverse section, showing the form. LITUITES mARSHII, HALL. Page 404. FIG. 6. Lateral view of a specimen of the natural size, showing the oblique costme and the out- line of the septa. 7. Profile showing the flattened dorsum, the concavity of the septa and the position of the siphuncle. TROCHOCERAS DESPLAINENSE, M'CHESNVEY. Page 401. FIG. 8. View of the upper side of spire, taken from an impression in the natural mould in the rock, showing the strong oblique costae. " 9. Dorsal view of the outer part of the last volution, showing the sinus in the margin of the aperture. 10. Transverse section, showing the convexity of the septa and position of the siphuncle. CYRTOCERAS FOSTERI, HALL. Page 406. FIG. 11. Lateral view of the specimen described. " 12. Dorsal view of the same. 13. Transverse section, showing the convexity of the septa and position of the siphuncle.