PLATE XXXI K— Continued. 

 Sttliola pissurella. 



Pago 178. 



Fig-8. 29, 30. Two individuals from the «oft calcareous shales of the Hamilton group, presenting- the prevailing 

 forms in that honzon, with suifaees entirely smooth. Fig-ure 29 is slig-htly bulbiform at the 

 apex ; fig-ure 30 is acute, presenting a depressed line along the middle of its length, which is 

 due to pressui-e. 



Figs. 31, 32. Two individuals, enlarged to six diameter.=<, showing strong longitudinal stris, and faint, trans- 

 verse annulafions; 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 

 CheiTy Valley, and are referred to ,Sf. fi/t.iure.lla var. gtrigata. 



Fig. 33. A more elorgate form, whei-e the striffi are obsolescent, being barely perceptible under a strong 

 lens, and appearing smooth under ordinary observation. The apex is distinctly bulbiform. 

 This form occui-s associated with those of figures 29 and 30, in the calcareous shales of the 

 Hamilt(m group. 



The forms illustrated in figures 29, 30 and 33 are referred to .S fissurella var. ohaolesceiis . 

 See page 180. 



Sttliola obtusa. 



Page 182. 

 Fig. 84. A fragment of shale covered with individuals of this form. Natural size. 

 Fig. 35. A small sjiecimen with a scai-cely perceptible bulbifoi-m apex. 



Fig. 36. A largei- 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 38, is somewhat 



contracted near the aperture, and free from annulations. 

 Figs. 39-42. Specimens of similar chai-acter, varying iu 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 ai-e moi-e acute, and somewhat unequally distant, with the 



apical portion marked only by longitudinal striae. 

 Rg. 44. A specimen, in the compact limesttme of the Marcellus shale, whei-e the annulations are sharply 



defined and continuing to the extremity, so far as preserved. 

 Fig. if>. A small si>ecimen from the Genesee slate, where the annulations are continued nearly to the apex. 

 Fig. 46. A fragment of shale, preserving Tbmtaculitbs and Sttliola 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 Tentaetdlt^ gracilistriatus, which preserve 



only slight undulations of the surface, with a single smooth Styliola. 



Tentaculites bellulus. 



Page im 



Pig. 48. A specimen partially denuded of the shell, the thickness of which is shown on each si<le of the 

 fig-ure. The annulations are irregular, and the tube contracted towards the aperture ; enlarged 

 to two diametei-8. 



Fig, 49. An individual partially donnded of the shell, and showing distant and irregular annulations. The 

 apex has become solidified from organic dejiosition, as shown in the lower part of the tigui-e. 



Fig. .W. The apical |)ortion of a specimen, where the annulations are regular and closely arranged through- 

 out. The figure i-epresents the specimen enlargeil to two diameters, and the surface is marked 

 by about sixty annulations. 



Fig. 51. A group of individuals of this 8pe'.:ie3, as they occur on the surface of the shale ; enlarged to three 

 diameters. 



