PLATE XXXVII. 
Orthoceras inoptatum. 
Page 267. 
See Plate 112. 
Fig-. 1. A fragment, retaining a large part of the chamber of habitation, and showing the regular frequency 
of the septa. From the Upper Helderberg limestone. Western New York. 
Orthoceras rudictjla. 
Page 268. 
See Plate 112. 
Fig. 2. A septate fragment, showing the rapid expansion of the tube, and the increase in the depth of the 
air-chambers from the apex toward the chamber of habitation. Stafford, N. Y. 
Orthoceras Pelops. 
Page 233. 
See Plates 35, 35 A, 78 B. 
Fig. 3. A septum, preserving the natural circular form of the transverse section. 
Fig. 4. A septum, showing an elliptical form, due to compression. Schoharie grit. Schoharie and 'the 
Helderberg mountains. 
Orthoceras viator. 
Page 270. 
Fig. 5. A fragment, preserving the chamber of habitation nearly entire, and portion of two of the air-cham¬ 
bers, partially showing the double constriction of the tube toward the aperture. Upper Hel¬ 
derberg limestone. Clarence Hollow, N. Y. 
Orthoceras CEdiphs. 
Page 294. 
See Plate 82. 
Fig. 6. A fragment, probably of the outer chamber, showing the surface ornaments Hamilton group. 
Geneseo, N. Y. 
Orthoceras profundtjm. 
Page 271. 
Fig. 7. A cast of the chamber of habitation, preserving its normal form and retaining the imprint of the 
surface-markings from the interior of the test. Williamsville, N. Y. 
Fig. 8. A fragment of the test of the grand chamber, showing the surface ornamentation. Black Rock, N. Y. 
Fig. 9. A partial cast of the chamber of habitation, preserving a portion|of the shell. Williamsville, N. Y. 
The specimens of this species are all from the limestone of the Upper Helderberg. 
