PLATE CXIII —Continued. 
Orthoceras textum. 
Page 285. 
Fig’. 14. An individual showing the form of the shell and the character of the surface-markings, which are 
preserved over the entire exterior of the tube. Limestone of the age of the Hamilton proup. 
Falls of the Ohio, near Louisville, Ky. 
Orthoceras tenere. 
Page 285. 
Fig. 15. An individual preserving several air-chambers near the apex, and showing the form of the tube. 
This specimen and the preceding of 0. textum have become silicified, and the internal charac¬ 
ters of the septa and siphuncle are obliterated. From limestone of the age of the Hamilton 
group. Falls of the Ohio, near Louisville, Ky. 
Orthoceras pustis. 
Page 281. 
See Plate 83. 
Fig. 16. The chamber of habitation entire, with several attached air-chambers. The septate portion is 
covered with the test and shows the surface characters. The chamber of habitation retains 
fragments of the test and shows the internal mould, which is marked by a decided constric¬ 
tion of the tube near the aperture, and a more gentle constriction near the base of the chamber. 
The aperture is entire, and a small fragment of the test presents its natural acute margin. 
Goniatite limestone. Schoharie, N. Y. 
Fig. 17. A septum of the preceding, showing the central position of the siphuncle. 
Orthoceras Marcellense. 
Page 278. 
See Plates 38, 83. 
Fig. 18. A fragment showing the internal mould of the air-chambers and the characters of the organic 
deposit. The larger extremity preserves three longitudinal carinae, of which the central one is 
stronger, and marks the ventral side of the tube. Proceeding in the direction of the apex, the 
organic deposit is first exhibited as small, irregular masses of calcareous matter, arranged 
somewhat symmetrically in regard to the ventral line. It increases in amount and complexity, 
until, at the smaller extremity, the cavities of the air-chambers are nearly filled with the 
deposit. Goniatite limestone. Manlius, N. Y. 
Orthoceras cochleatum. 
Page 308. 
Fig. 19. An individual nearly entire, showing the form of the tube and the curvature and obliquity of the 
septal sutures. The chamber of habitation shows a slight constriction of the tube near the 
aperture, with a contraction at the aperture, and preserves traces of transverse lamellose 
surface-markings. Upper Chemung group. Warren, Pa. 
Orthoceras bipartitum. 
Page 313. 
Fig. 20. A small fragment preserving a portion of the grand chamber, with ten attached air-chambers, 
showing the prominent annulations on the chamber of habitation, and their absence over the 
septate portion. The internal mould preserves traces of shaiq) longitudinal striae and trans¬ 
verse lines of growth. 
