PLATE CXI. 
Trochoceras obliquatum. 
Page 401. 
See Plate 58. 
Pig. 1. Upper lateral view of a fragment, showing the curvature of the tube and the depth of the air- 
chambers. Schoharie grit. Schoharie, N. Y. 
Fig. 2. A septum of the preceding, showing the transverse section of the tube and the position of the 
siphuncle. 
Trochoceras Pandion. 
Page 400. 
See Plate 58. 
Fig. 3. Lateral view of a septate fragment, showing the curvature of the tube, the depth of the air-chambers 
and some traces of the furrows of the crenulations continued over the internal mould of the 
walls of the air-chambers. Schoharie grit. Schoharie, N. Y. 
GoNIOCERAS ? PANDUM. 
Page 403. 
Fig. 4. A fragment imbedded in the surrounding rock, showing one of the angles of the tube, the variation 
in the depth of the air-chambers, and the curvature of the sutures over the broad, flat faces of 
the tube. Schoharie grit. Schoharie, N. Y. 
Trochoceras expansum. 
Page 402. 
See Plate 58. 
Fig. 5. Dorsal view of a portion of a small individual, showing the form of the shell and the transverse 
section of the tube, with the siphuncle on the convex ventral side. The slight departure from 
a symmetrical coil, and its nautiloid character, are also indicated. Schoharie grit. Scho¬ 
harie, jy. y. 
Trochoceras Clio. 
Page 392. 
See Plate 59. 
Fig. 6. The upper side of a small individual, showing oblique annulations, with the septa at right angles to 
the spiral axis, and crossing the annulations. Schoharie grit. Schoharie, N. Y. 
Trochoceras Biton. 
Page 395. 
Fig. 7. A fragment showing the curvature of the tube, and the linear nodes which are prominent on the 
concave dorsal side, and extend as rounded, transverse undulations to the convex ventral side. 
The surface-markings are preserved over a small portion of the tube, and show as strong longi¬ 
tudinal striae. Schoharie grit. Clarksville, N. Y. 
Trochoceras Barrandei. 
Page 398. 
Fig. 8. The siphuncle of a specimen which has broken longitudinally along the ventral line, and exposed the 
siphuncular tube, showing the amount of its expansion in the cavities of the air-chambers, and 
the striations of its surface at the constrictions where it passes through the septa. Schoharie 
grit. Clarksville, N. Y. 
