PLATE LXXVIII B. 
Orthoceras masculem. 
Page 238. 
Fig. 1. A fragment showing the great depth of the chambers, and gradual enlargement of the tube. The 
crenulations of the upper margin of the chamber walls, impressed upon the interior cast, are 
shown along the septal line of several of the chambers. Clarksville, N. Y. 
Orthoceras Pelops. 
Page 233. 
See Plates 35, 35 A, 37. 
Fig. 2. An individuaLof this species retaining a large portion of the chamber of habitation, and eleven other 
chambers. The sinuate direction of the striae upon the chamber of habitation is not due to a 
proper sinus of the ornamentation, but to the repairing of a fracture in the shell, which had 
thus become thickened and is preserved, while the other portions are dissolved. Knox, N. Y. 
Orthoceras ltjxum. 
Page 214. 
See Plates 35, 76, 77, 78, 81, 112. 
Fig. 3. Longitudinal section showing the elements of the siphuncle, and amount of organic deposit. The 
specimen is the same as the one figured on plate 77, figure 8, where the details are not suffi¬ 
ciently or accurately represented. 
Orthoceras tetricum. 
Page 251. 
See Plate 80. 
Fig. 4. A septate fragment preserving the test as replaced by the material of the rock. Several individuals 
of a species of Spirorbis are attached to the upper portion. Clarksville, N. F. 
Orthoceras Thoas. 
Page 261. 
See Plates 41, 79, 80, 112. 
Fig. 5. A fragment retaining a large portion of the chamber of habitation and four other chambers 
Remains of the surface-markings are preserved on a portion of the tube. This specimen 
illustrates the extreme variation in the prominence and distance of the annulations. Clarks¬ 
ville, N. Y. 
