to very different habitats in brackish and in salt water; in the several zones of shallow, deep, and abyssal seas; and under every climate, from the poles to the equator. In arranging our synoptical tables of the Mediterranean Rhizopoda, recent and fossil, and in comparing their numerous specific and varietal forms one with another, we have not confined ourselves to our collections from this region, but have necessarily made comparisons of forms from almost every part of the globe; from the Arctic and the Tropic Seas; from the temperate zones of both hemispheres; and from shallow, as well as deep sea-beds. Geologically, also, we have reviewed the Foraminifera in their manifold aspects, as presented by the ancient Faunas of the Tertiary, Cretaceous, Oolitic, Liassic, Triassic, Permian, and Carboniferous times; finding, to our astonishment, that scarcely any of the species of Foraminifera met with in the Secondary Rocks have become extinct; all, indeed, that we have yet seen have their counterparts in the recent Mediterranean deposits. This is still more clearly found to be the case with regard to the Chalk of Maestricht and the Tertiaries"[1]. And the same excellent observers, in summing up their description of the Foraminifera of the blue clay met with in the alabaster pits at Chellaston, near Derby, belonging to the Upper Triassic series, thus express themselves:—"Having thus pointed out that, judging from these specimens obtained at Chellaston, the minute Nodosarinæ and other Foraminifera of the Triassic period have continued to exist through the intermediate ages to the present day, without losing any of their essentially specific features, we will observe that the Nodosariæ are present in rocks of still greater age than the Trias,—namely, the Permian and Carboniferous, and probably even the lower Silurian. Nodosariæ and Dentalinæ abound in some of the Permian limestones of Durham and the Wetterau, in company with Textulariæ. Nodosaria occurs also in the Carboniferous limestone of Ireland, according to M'Coy; and the green sand of the lower Silurian series, near St. Petersburg, has yielded to Ehrenberg casts of chambers something like those of Dentalina, together with unmistakeable casts of Testularian and Rotalian shells. We may remark, too, that the Fusulina of the Russian, North American, and Arctic Mountain-limestone carries back the pedigree of the Nonionina group to the Palæozoic periods; and that it is accompanied with other Foraminifera of known types, amongst which Nummulina is not absent. This last-named type has rare representatives in the Lias and Oolite; it acquired great potency in the Tertiary seas, and is not extinct now. Altogether we have here some remarkable instances of the persistency of life-types among the lower animals. Though the specific relations of the Palæozoic Foraminifera require further elucidation, we feel certain that the six genera, represented in this Upper Triassic clay of Chellaston by about
- ↑ "On the Rhizopodal Fauna of the Mediterranean, compared with that of the Italian and some other Tertiary Deposits," in the Quarterly Journal of the Geological Society for August, 1860, p. 294.
