PLATE LXXXV. 
Orthoceras exile. 
Page 290. 
See Plates 39, 84. 
Fig. 1. The chamber of habitation, with two of the attached air-chambers, showing the regular enlarge¬ 
ment of the tube to the aperture. 
Fig. 2. A septum of the preceding, showing the circular, transverse section of the tube and the excentric 
position of the siphuncle. 
Fig. 14. A chambered fragment of an individual referred with doubt to this species. The specimen has 
been much macerated and distorted in the soft shales, which has obscured the specific charac¬ 
ters. The exterior shows numerous furrows where the shell has been invaded by some 
terebrous animal. East shore of Cayuga lake, N. Y. 
Fig. 15. A specimen in the same association, and similar to the preceding. The apparent expansion and 
constriction of the tube is due to the action of iron pyrites. 
Orthoceras Telamon. 
Page 201. 
Fig 3. The chamber of. habitation of an example, showing its cylindrical form and the absence of any con¬ 
striction or expansion at the aperture. 
Fig. 4. A septum of the preceding, showing the transverse section of the tube and the very excentric 
position of the siphuncle. 
Fig. 12. Ventral view of a small, chambered fragment, showing the depth of the chambers and the gradual 
enlargement of the tube. A low, longitudinal carina along the ventral side is not represented. 
The specimens of this species here represented are from the shales of the Hamilton group, at 
Monteitlis Point, Canandaigua lake, N. Y. 
Orthoceras constrictum. 
Page 2S8. 
See Plate 84. 
Fig. 5. A fragment of the chamber of habitation, with two of the attached air-chambers, showing a decided 
constriction of the tube at the upper extremity. Cazenonia, JST. Y. 
Fig. 10. A fragment retaining a portion of the chamber of habitation and twenty-one air-chambers, showing 
the very gradual increase in their depth toward the grand chamber. Cazenovia, IV. Y. 
Fig. 11. A chambered fragment, retaining nearly its normal form and proportions. Monteith's Point, 
Canandaigua lake, N. Y. 
Fig. 13. A septum of another fragment, showing the position of the siphuncle and the circular, transverse 
section of the tube. Monteith’s Point, Canandaigua lake, N. Y. 
Orthoceras spissum. 
Page 287. 
Fig. 6. A fragment embracing a portion of the chamber \of habitation and fifteen air-chambers, showing the 
frequency of the septa and the regular depth of the air-chambers. Pratt's Falls, Onondaga 
county, N. Y. 
Fig. 7. A septum of the preceding, showing the position and size of the siphuncle. The section as repre¬ 
sented is nearly circular, whereas the transverse section of the tube is broadly elliptical. 
Fig. 8. A poi'tion of a larger individual, exhibiting the same characters as the preceding example. Pratt’s 
Falls, Onondaga county, N. Y. 
Fig. 9. A septum of the preceding specimen, showing the position of the siphuncle. This figure is also too 
nearly circular in outline. It should be flattened in a dorso-ventral direction. 
