Geology and Mineralogy considered with reference to Natural Theology/Plate 38
Plate 38. V. I. p. 262. Note.
Air-chambers of Ammonites heterophyllus, filled with
Lias, and showing in a remarkable degree the effect of the
undulating course of the edges of the transverse plates beneath
the flat sides of the outer shell.
A portion of the outer shell is preserved at c. and impressions of the fluted interior of the shell, which has fallen off, are visible at d. (Original.)