PLATE XXXI A—Continued. 
Styliola fissurella. 
Page 178. 
Figs. 29, 30. Two individuals from the soft calcareous shales of the Hamilton group, presenting the prevailing 
forms in that horizon, with surfaces entirely smooth. Figure 29 is slightly bulbiform at the 
apex ; figure 30 is acute, presenting a depressed line along the middle of its length, which is 
due to pressure. 
Figs. 31, 32. Two individuals, enlarged to six diameters, showing strong longitudinal striae, and faint, trans¬ 
verse annulations; the smaller one is slightly expanded at the apex, and the larger one 
distinctly bulbiform. These specimens are from the calcareous band in the Marcellus shale at 
Cherry Valley, and are referred to S. fissurella var. strigata. 
Fig. 33. A more elongate form, where the strias are obsolescent, being barely perceptible under a strong 
lens, and appearing smooth under ordinary observation. The apex is distinctly bulbiform. 
This form occurs associated with those of figures 29 and 30, in the calcareous shales of the 
Hamilton group. 
The forms illustrated in figures 29, 30 and 33 are referred to /S' fissurella var. obsolescens. 
See page 180. 
Styliola obtitsa. 
Page 182. . 
Fig. 84. A fragment of shale covered with individuals of this form. Natural size. 
Fig. 35. A small specimen with a scarcely perceptible bulbiform apex. 
Fig. 36. A larger individual with the apex bulbiform. The surface is entirely smooth. From the shales of 
the Hamilton group. 
Tentaculites gracilistriatus. 
Page 173. 
Figs. 37, 38. Specimens of similar character with the apices acute. The specimen, figure 33, is somewhat 
contracted near the aperture, and free from annulations. 
Figs. 39-42. Specimens of similar character, varying in the proportional number and distance of the 
annulations, and in the comparative length of the smooth part of the tube towards the apex. 
The apices are all bulbiform. From the soft shales of the lower part of the Hamilton group. 
Fig. 43. A similar form, where the annulations are more acute, and somewhat unequally distant, with the 
apical portion marked only by longitudinal striae. 
Fig. 44. A specimen, in the compact limestone of the Marcellus shale, where the annulations are sharply 
defined and continuing to the extremity, so far as preserved. 
Fig. 45. A small specimen from the Genesee slate, where the annulations are continued nearly to the apex. 
Fig. 46. A fragment of shale, preserving Tentaculites and Styliola upon its surface, and presenting the 
usual conditions, as they occur in the shales of the lower part of the Hamilton group; enlarged 
to six diameters. 
Fig. 47. A small fragment of shale with the apical portions of Tentaculites gracilistriatus, which preserve 
only slight undulations of the surface, with a single smooth Styliola. 
Tentaculites bellulus. 
Page 169. 
Fig. 48. A specimen partially denuded of the shell, the thickness of which is shown on each side of the 
figure. The annulations are irregular, and the tube contracted towards the aperture; enlarged 
to two diameters. 
Fig. 49. An individual partially denuded of the shell, and showing distant and irregular annulations. The 
apex has become solidified from organic deposition, as shown in the lower part of the figure. 
Fig. 50. The apical portion of a specimen, where the annulations are regular and closely arranged through¬ 
out. The figure represents the specimen enlarged to two diameters, and the surface is marked 
by about sixty annulations. 
Fig. 51. A group of individuals of this species, as they occur on the surface of the shale ; enlarged to three 
diameters. 
