PLATE LXXXIX. 
Orthoceras pacator. 
Page 307. 
Fig. 1. A fragment of a large individual embracing a portion of the tube near the chamber of habitation, 
and showing considerable irregularity and variation in the depth of the air-chambers. The 
specimen is much flattened from compression in the soft shales, and many of its features 
obscured. Portage group. Mt. Morris, Livingston county, N. Y. 
Fig. 2. A fragment of a small, compressed individual, showing the constriction of the tube near the aper¬ 
ture, and a curvature and obliquity of the suture?, due to compression. 
Fig. 3. An incomplete individual retaining its normal proportions, and showing the chamber of habitation 
nearly entire. The last two air-chambers are not shown in the figure, making the chamber of 
habitation appear longer than its true proportions.' 
Fig. 4. A septum of a larger individual, referred to this species with doubt. The tube is somewhat com¬ 
pressed on one side, and the true position of the siphuncle is not shown. From a septum of 
specimen figure 3, it is seen that the siphuncle is more excentric than is here represented. 
Fig. 5. A septate portion, showing the regular increase in the depth of the air-chambers from the apex, and 
their irregularity near the outer chamber. Portage group. Ithaca, N. Y. 
Fig. 6. A fragment of the chamber of habitation, with several attached air-chambers, showing the inequality 
of the last air-chamber. Portage group.' ItJiaca, IV. Y. 
Orthoceras, sp. indet. 
Fig. 7. A fragment of undetermined, specific relations, which has been incrusted with a Bryozoan of peculiar 
character. 
Fig. 8. A portion of the surface enlarged, showing the epitheca and bases of the cell-pores, as exposed upon 
a weathered surface. 
Orthoceras anguis. 
Page 312. 
Fig. 9. A compressed fragment, showing the gradually enlarging tube, and the regular, transverse, 
lamellose strife of the surface. Lower part of the Chemung group. CascacLilla Creek, Upper 
Fall, Ithaca, N. Y. 
Orthoceras Atreus. 
Page 305. 
See Plate 8S. 
Fig. 10. A chambered fragment, preserving its natural cylindrical form, and showing the depth of the air- 
chambers. Calcareous beds of the Portage group at Penn Yan, Yates county, N. Y. 
Fig. 11. A septum of'a small fragment, preserving several chambers, and showing the size and excentric 
position of the siphuncle. The specimen is referred to this species with some doubt. 
