Page:Philosophical Transactions - Volume 054.pdf/74

 no more convolutions could be carried on; the indented lips being a full stop to its inward dimensions; and that here was the period of its growth. My sentiments were just as to its inward dimension; but observing that the lips of some were much larger than others, and that the curved part of the outer lip appeared thicker, when sawed open, than the other parts of the shell; I began to think, that the animal, instead of enlarging the inner dimensions, was employed in thickening the outer wall, to guard against injuries and accidents, so common to the inhabitants of that turbulent element the sea. I was the more confirmed in these sentiments by seeing the beautiful spots, with which this animal decorates its house, covered by other spots of different colour and size, as new laminæ were added to strengthen the last-formed convolution. It is really matter of admiration to see how these shells are adorned and variegated; the exquisite polish; which covers the whole infinitely surpassing the skill even of the most accomplished human artist. These new coverings or laminæ, which are carried from the lips, terminate in the middle of the back part of the shell; and there form a list, or seam, of a quite different colour from that of the other part of the shell, and of an unequal surface.

This very circumstance gave birth to my sentiments concerning the formation of the Belemnite: for whoever considers the seam or sulcus in the Belemnite, will, I think, conclude with me, that the outward lamina is formed latest, as in the cowree, and that the seam or sulcus is caufed by the several additional coverings or laminæ terminating there. But as the anatomist makes fresh difcoveries by dissecting the