PLATE XLII. 
Orthoceras crotalum. 
Page 296. 
See Plates 82, 113. 
Fig. 1. A portion of the chamber of habitation, showing the absence of annotations near the aperture, and 
the strong, lamellose, striate surface of the internal mould. Schoharie county, N. Y. 
Fig. 2. A specimen similar to the preceding, with the annulations more prominent, and slightly oblique. 
Pratt's Falls, N. Y. 
Fig. 3. A fragment somewhat compressed, showing the marked annulations, and the depth of the air- 
chambers. Cazenovia, N. Y. 
Fig. 4. A more slender specimen, showing the amount of compression, and the obliquity of the annulations, 
with the septal sutures intersecting them by planes oblique to the axis of the tube, and to the 
direction of the annulations. Cazenovia, N. Y. 
Fig. 5. A small, septate fragment, preserving the characteristic, fine, longitudinal strise over the exterior of 
the tube. Hamilton, N. Y. 
Fig. 6. The'chamber of habitation nearly entire, showing the absence of annulations near the aperture, and 
a portion of a broad retral curve in the annulations over one side. 
Fig. 7. A fragment showing the increase in the distance and prominence of the annulations from the apex 
toward the outer chamber. Otisco Lake, N. Y. 
Fig. 8. A compressed fragment, exhibiting the same characteristics as the preceding specimen. Hamil¬ 
ton, N. Y. 
Fig. 9. A lateral view of the same, showing the amount of compression. 
Fig. 11. A portion of the surface enlarged from specimen fig. 5, showing the fine, regular, longitudinal 
strise. Two of the septal sutures are shown in the upper furrow. 
Fig. 12. A fragment of a large individual'with more distant annulations. Greneseo, Livingston county, N. Y. 
Orthoceras cjelahen. 
Page 298. 
See Plates 43, 82, 113. 
Fig. 10. An imperfect specimen, retaining portions of the test, and showing about twenty annulations. North 
Bristol, Ontario county, N. Y. 
