Orthoceras Sicinus. 
Page 301. 
Fig. 1. A fragment showing the form and proportions of the shell, with the obscure simulations and sur¬ 
face-markings. The annulations are not represented sufficiently distinct. Marcellos shale* 
Avon, N. Y. 
Fig. 2. An enlargement of the surface of the preceding specimen, showing the rounded annulations and 
reticulate surface. 
Orthoceras subulatum. 
Page 283. 
See Plates 84, 86. 
Fig. 8. The original of the species, which is nearly entire, preserving the chamber of habitation. The 
specimen is flattened from pressure in the shale. Marcellus shale. Bloomfield, N. Y. 
Orthoceras Marcellense. 
Page 278. 
See Plate 83, 113. 
Fig. 4. A frag-ment preserving several of the air-chambers, and a portion of the test with the external 
markings. 
Fig. 5. The ventral side of a larger fragment retaining portions of the test over the surface, and the carina 
on the internal mould, which is too prominently represented along the chamber of habitation 
towards the aperture. 
Fig. 6. A nearly entire individual showing the length of the outer chamber and the increase in the frequency 
of the septa toward the apex. The peculiar‘organic deposit and ornamentation of the internal 
cast, shown in the specimen, are not represented in the figure. The apex is represented as 
entire, but several air-chambers are wanting in the specimen. 
Fig. 7. A larger example, imperfect at both extremities, retaining* fragments of the test on different parts of 
the surface. 
Fig. 9. An enlargement of the surface, showing the transverse strife interrupted by longitudinal lines. 
The above specimens are all from the Goniatite limestone of the Marcellus shale. Manlius, 
Marcellus, and other places in New York. 
Orthoceras aptum. 
Page 2S2. 
Fig. 8. An individual preserving the greater portion of the chamber of habitation, and- over thirty air- 
chambers, showing the gradually enlarging tube, and the curved and oblique septal sutures : 
dorsal view. Goniatite limestone. Manlius, N. Y. 
Orthoceras Bebryx. 
Page 275. 
See Plates 39, S3, 84. 
Fig. 10. A large fragment of the septate porlion, retaining a part of the chamber of habitation. Hamilton 
shales. Cazenovia, N. Y. 
