PLATE XXII A. 
StYLIOLA EISSURELLA. 
!; Page ( 178. 
Fig. 1. A fragment of slate with numerous crushed specimens of the fossil, enlarged to three diameters. 
Figs. 2-6. Individuals from the surface of the slate, showing the variety of form and surface-markings: 
fig. 2 being strongly striate longitudinally; fig. 3 showing transverse and longitudinal striae; 
and fig. 4 preserving only transverse strise ; while figs. 5 and 6 are without visible strise under 
an ordinary lens. All the .preceding figures are from the Marcellus shale.. Figs.-2-6 are 
enlarged to six diameters. 
Fig. 7. A fragment of the Genesee slate cpvered with Styliola jisaurella, enlarged to three diameters. 
All the following figures are enlarged to six diameters unless otherwise indicated. 
Fig. 8. A crushed specimen showing obscure transverse strise ; the apex acute. 
Fig. 9. A crushed specimen without visible transverse stria;, and with the extremity bulbiform. 
Fig. 10. A specimen in its natural proportions, the margin of the aperture broken away on one side. ' The 
surface is obscurely marked by transverse strise, and the extremity slightly bulbiform. 
Fig. 11. An individual which is apparently contracted near the aperture, with the surface faintly striate 
concentrically, and the apex acute. 
Fig. 12. A smaller form similar to the preceding, without visible transverse striae. 
Fig. 13. A larger compressed specimen with obscure transverse strise. 
Fig. 14. A portion of an individual where the transverse strise are more closely arranged, and more con¬ 
spicuous. 
Fig. 15. An individual of large size, where the lower part of the tube is essentially smobth, or preserving 
only obscure concentric strise, while towards the aperture these strise become much stronger, 
and are cancellated by longitudinal strise; the latter being visible only so far as shown in the 
figure. All the figures from 11-15 inclusive have no perceptible expansion at the apex. 
Fig. 16, a, b, c. Specimens showing an apparently intermittent mode of growth. 
Fig. 17. A specimen showing tlfe insertion of one individual within another; the outer broken margin 
being of the shell, and the intermediate portion the filling of mineral matter between the two. 
It is probable that some of the irregular specimens referred to intermittent growth may be due 
to conditions similar to fig. 17; but in other examples it is clearly the mode of growth. 
Figs. 18, 19. Two small individuals of regular form and acute apices, with faint, transverse' undulations, 
which are scarcely defined as striae. 
Fig. 20. Three individuals lying in juxtaposition and preserving their natural proportions; two of them 
show evidence of intermittent growth, and are contracted near the aperture, while the third one 
is simple. The surfaces are marked by faint undulations or obsolete strise. 
Fig. 21. A short, broad form, the breadth increased by compression. 
Fig. 22. A short, broad specimen with the aperture entire. From the Genesee slate. Lexington, Indiana. 
Figs. 23, 24. Two individuals of slightly different shape (fig. 23 being a little more compressed), both of 
which have the surface distinctly cancellated by fine, longitudinal and transverse strise. 
Fig. 24 is slightly bulbiform at the extremity, while fig. 23 is acute. 
Fig. 25. A fragment showing the cleavage surface of a calcareous layer in the Genesee slate, which is 
chiefly composed 'of Styliola with a few Tentaculites. Natural size. Cayuga creek, Erie 
county, N. Y. 
Fig. 25 a. A polished, translucent section from a calcareous layer in the Marcellus shale, showing the trans¬ 
verse and longitudinal sections of Styliola ; enlarged to three diameters. Cherry Valley, N. Y- 
Figs. 26, 27 and 28 are very minute, slender forms of Styliola enlarged to six diameters, as in the preceding 
and following figures of this species. The apices are slightly bulbiform; and on figure 27 
there are obsolescent strife, while figures 26 and 28 are smooth. From the compact layer 
composed of the shells of Styliola, in the Genesee slate. Cayuga creek, Erie county, N. Y. 
The figures from 7 to 28 inclusive, except 25 a, are from the Genesee slate. The figures 29 
and 30, and 33-36, are from the shales in the lower part of the Hamilton group, above the 
Marcellus shale. 
