The Globigerina of the present day, for example, is not different specifically from that of the chalk; and the same maybe said of many other Foraminifera.

As I have pointed out elsewhere, it at once became obvious that the calcareous sticky mud of the Atlantic was made up, in the main, of shells of Globigerina and other Foraminifera, identical with those of which the true chalk is composed, and the identity extended even to the presence of those singular bodies, the Coccoliths and Coccospheres, the true nature of which is not yet made out.

Thus besides Globigerina, there are eighteen species of deep-sea Foraminifera identical with species found in the chalk.

Thus, in the whole of the "intermediate zone," the silicious deposit which is being formed there, as elsewhere, by the accumulation of sponge- spicula, Radiolaria, and Diatoms, is obscured and overpowered by the immensely greater amount of calcareous sediment, which arises from the aggregation of the skeletons of dead Foraminifera.

"] Ehrenberg appears to have taken it for granted that the Globigerinoe and other Foraminifera which are found in the deep-sea mud, live at the great depths in which their remains are found; and he supports this opinion by producing evidence that the soft parts of these organisms are preserved, and may be demonstrated by removing the calcareous matter with dilute acids.

"Had the Globigerinoe been drifted into their present position from shallow water, we should find a very large proportion of the characteristic inhabitants of shallow waters mixed with them, and this would the more certainly be the case, as the large Globigerinoe, so abundant in the deep-sea soundings, are, in proportion to their size, more solid and massive than almost any other Foraminifera.

But the fact is that the proportion of other Foraminifera is exceedingly small, nor have I found as yet, in the deep-sea deposits, any such matters as fragments of molluscous shells, of Echini, &c., which abound in shallow waters, and are quite as likely to be drifted as the heavy Globigerinoe.

Whatever may be the mode of life of the Foraminifera, to which the calcareous element of the deep-sea "chalk" owes its existence, the fact that it is the chief and most widely spread material of the sea-bottom in the intermediate zone, throughout both the Atlantic and Pacific Oceans, and the Indian Ocean, at depths from a few hundred to over two thousand fathoms, is established.

Professor Bailey, examining these grains microscopically, found that they were casts of the interior cavities of Foraminifera, consisting of a mineral known as Glauconite, which is a silicate of iron and alumina.

Contemporaneously with these observations, the indefatigable Ehrenberg had discovered that the "greensands" of the geologist were largely made up of casts of a similar character, and proved the existence of Foraminifera at a very ancient geological epoch, by discovering such casts in a greensand of Lower Silurian age, which occurs near St. Petersburg.

It would appear that this infiltration of Foraminifera shells with Glauconite does not take place at great depths, but rather in what may be termed a sublittoral region, ranging from a hundred to three hundred fathoms.

The smaller Foraminifera now give way, and are found in lessening proportion to the larger; the coccoliths first lose their thin outer border and then disappear; and the clubs of the rhabdoliths get worn out of shape, and are last seen, under a high power, as infinitely minute cylinders scattered over the field.

"In the meantime the proportion of the amorphous 'red clay' to the calcareous elements of all kinds increases, until the latter disappear, with the exception of a few scattered shells of the larger Foraminifera, which are still found even in the most characteristic samples of the 'red clay.'

An ordinary mixture of calcareous Foraminifera with the shells of pteropods, forming a fair sample of Globigerina ooze from near St. Thomas, was carefully washed, and subjected by Mr. Buchanan to the action of weak acid; and he found that there remained after the carbonate of lime had been removed, about 1 per cent.

Next, imagine sponges, Radiolaria, Foraminifera, and diatomaceous plants, such as those which now exist in the deep-sea, to be introduced: they would be distributed according to the same laws as at present, the sponges (and possibly some of the Foraminifera), covering the bottom, while other Foraminifera, with the Radiolaria and Diatomacea, would increase and multiply in the surface waters.

Next, imagine sponges, Radiolaria, Foraminifera, and diatomaceous plants, such as those which now exist in the deep-sea, to be introduced: they would be distributed according to the same laws as at present, the sponges (and possibly some of the Foraminifera), covering the bottom, while other Foraminifera, with the Radiolaria and Diatomacea, would increase and multiply in the surface waters.

Next, imagine sponges, Radiolaria, Foraminifera, and diatomaceous plants, such as those which now exist in the deep-sea, to be introduced: they would be distributed according to the same laws as at present, the sponges (and possibly some of the Foraminifera), covering the bottom, while other Foraminifera, with the Radiolaria and Diatomacea, would increase and multiply in the surface waters.

The most ancient forms recently made known by Ehrenberg are exceedingly like those which now exist: no one has ever pretended that the difference between any ancient and any modern Foraminifera is of more than generic value, nor are the oldest Foraminifera either simpler, more embryonic, or less differentiated, than the existing forms.

The most ancient forms recently made known by Ehrenberg are exceedingly like those which now exist: no one has ever pretended that the difference between any ancient and any modern Foraminifera is of more than generic value, nor are the oldest Foraminifera either simpler, more embryonic, or less differentiated, than the existing forms.

CUSHMAN, ALICE E. Foraminifera.

CUSHMAN, JOSEPH AUGUSTINE. Foraminifera; their classification and economic use.

Foraminifera: their classification and economic use; with an illustrated key to the genera.

CUSHMAN, ALICE E. Foraminifera.

CUSHMAN, JOSEPH AUGUSTINE. Foraminifera; their classification and economic use.

Foraminifera: their classification and economic use; with an illustrated key to the genera.