PLATE LXXXIIL 
Orthoceras Marcellense. 
Page 278. 
See Plates 38, 113. 
Fig. 1. Ventral view of a fragment showing, on the cast, a longitudinal convex line on each side of the 
median carina. 
Fig. 2. Ventral view of a larger fragment preserving portions of the test, and showing the ventral carina 
along the internal mould of the air-chambers. Goniatite limestone. Manlius, iV. Y. 
Fig. 3. A longitudinal section showing the position and elements of the siphuncle, and the depth of the air- 
chambers. 
Fig-. 4. A septum, showing the elevated areola around the siphuncle, and its extension to the ventral side. 
Fig. 5. Ventral view of the same, showing the elevation of the areola, and the continuation of the areolar 
process over the walls of the air-chamber. These two figures are from the lower extremity of 
specimen figure 2. 
Fig. 6. A septum showing the elevated areola and radiating vascular markings, extending to the margins. 
Fig. 7. A septum showing a simple areola without extension to the ventral margin, and surrounded by 
obscure, radiating, vascular markings. 
Fig. 8. A septum nearer the outer chamber, without distinct areolar markings, showing the position of the 
siphuncle. Manlius, N. Y. 
Fig. 9. The concave surface of a septum, which has become distorted from compression. 
Fig. 10. An enlargement of the surface, showing broad, flat, transverse strise, without any evidences of lon¬ 
gitudinal markings. 
Fig. 12. An enlargement similar to the preceding, from another part of the specimen, with sharper striae 
of growth, and strong longitudinal lines. 
Orthoceras fustis. 
Page 281. 
See Plate 113. 
Fig. 11. A portion of the surface enlarged, showing the minutely undulating striae of growth, and fine longi¬ 
tudinal strise. Schoharie, N. Y. 
Orthoceras, sp. undetermined. 
Page 301. 
' Fig. 13. A fragment of undetermined specific relations. The surface of a septum is covered with numerous 
individuals of a species of Spirorbis. Hamilton group. Ontario, Canada West. 
Orthoceras Bebrtx. 
Page 275. 
See Plates 38, 39, 84. 
Fig. 14. A fragment much compressed and weathered, with the siphuncle exposed, showing its elements. 
Skaneateles Lake, 2V. Y. 
