The Nummulites, like the Nautilus and Ammonite, are divided into air-chambers, which served the office of a float: but there is no enlargement of the last chamber which could have contained any part of the body of the animal. The chambers are very numerous, and minutely divided by transverse plates; but are without a siphuncle.[1] The form of the essential parts varies in each species of this genus, but their principles of construction, and manner of operation, appear in all to have been the same.
The remains of Nummulites are not the only animal bodies
which have contributed to form; the calcareous strata
of the crust of the earth; other, and more minute species of
Chambered shells have also produced great, and most surprising
effects. Lamarck (Note, v. 7. p. 611,) speaking of
the Miliola, a small multilocular shell, no larger than a millet
seed, with which the strata of many quarries in the neighbourhood
of Paris are, largely interspersed, notices the important
influence which these minute bodies have exercised
by reason of their numerical abundance. We scarcely condescend,
>br />the Clio Borealis, that in calm weather, the surface of the water in these seas swarms with such millions of these mollusks (rising for a moment to the air at the surface, and again instantly sinking towards the bottom,) that the whales can scarce open their enormous mouths without gulping in thousands of these little gelatinous creatures, an inch long, which, together with Medusæ, and some smaller animals, constitute the chief articles of their food; and we have a farther analogy in the fact mentioned in Jameson's Journal, vol. ii. p. 12. "That the number of small Medusæ in some parts of the Greenland seas is so great, that in a cubic inch, taken up at random, there are no less than 64. In a cubic foot this will amount to 110,592; and in a cubic mile (and there can be no doubt of the water being charged with them to that extent,) the number is such, that allowing one person to count a million in a week, it would have required 80,000 persons, from the creation of the world, to complete the enumeration."—See Dr. Kidd's admirable Introductory Lecture to a course of Comparative Anatomy, Oxford, 1824, p. 35.
- ↑ In Pl. 44, Figs. 6, 7. sections of two species of Nummulite are copied from Parkinson. These show the manner in which the whorls are coiled up round each other, and divided by oblique septa.
