^{page 506 note *} Zeitschr. für Wissen. Zoologie, vol. xiii. p. 563.

^{page 506 note †} New Zealand, New Caledonia, and the Seychelles have primitive rocks, if these can be regarded as oceanic islands. Some of the islands between New Caledonia and Australia may have primitive rocks, and the atolls in these regions may be situated on foundations of this nature.

^{page 506 note ‡} Proc. Roy. Soc. Edin., 1876–77, p. 247.

^{page 507 note *} Scrope on Volcanoes, chap, viii,

^{page 508 note *} The Challengeridæ, and many of the other members of Haeckel's new order Phœodaria, certainly live deeper, as we never got them in the tropics except when the net was sent down to a depth of 200 or 300 fathoms.

^{page 508 note †} Among the varieties of Foraminifera recognised by Mr Brady in the “Challenger” collections, the following have a Pelagic habitat:—

It is the dead shells of these Pelagic Foraminifera which chiefly make up the calcareous oozes of the deep sea. The living shells of all the above varieties swarm in the tropical and sub-tropical waters near the surface. It is especially in the region of the equatorial calms that the largest and thickest shelled specimens are found. As we go north or south into colder water they become smaller, and many varieties die out. In the surface waters of the Arctic and Antarctic regions, only some dwarfed specimens of Globigerina bulloides are met with. The author is unable to agree with Dr Carpenter and Mr Brady in thinking that these Pelagic Foraminifera also live on the bottom. This question was made the subject of careful investigation during the cruise. The shells from the surface and from the bottom were compared at each locality, and it was found, by micrometric measurement, that surface specimens were as large and as thick shelled as any average specimens from the soundings. It is quite unlikely that the same individuals should pass a part of their lives in the warm sunny surface waters, at a temperature of from 70° to 80° Fahr., and another part in the cold dark waters two or three miles beneath, at a temperature of 30° or 40° Fahr. The geographical distribution of these Pelagic forms over the bottom coincides exactly with the distribution of the same forms on the surface; that is to say, both on the surface and on the bottom, the distribution is ruled by surface temperature. No specimens of these Pelagic varieties were ever obtained from the bottom with the shells filled and surrounded with sarcode. Whereas creeping and attached forms (like Truncatulina, Discorbina, Anomalina and some Textulariæ) were taken in this condition in almost every dredge. These last-mentioned forms which we know live on the bottom have a distribution quite independent of surface temperature.

^{page 510 note *} Coral Reefs, p. 118.

^{page 511 note *} Coral Reefs, p. 134.

^{page 511 note †} There are no living corals or shells in some small lagoons, the waters of which become highly heated, and in some cases extremely saline.

^{page 512 note *} Complete little Serpula-atolls, with lagoons from 3 to 50 feet in diameter, and formed in this way without subsidence, were numerous along the shores of Bermuda.

^{page 512 note †} Mr Darwin's application of his theory to this group—where the disseverment of large atolls is called in, and a destructive power attributed to oceanic currents, which it is very unlikely they can ever possess–has often been considered unsatisfactory.

^{page 512 note ‡} “In speaking of Bow Island, Belcher mentions the fact that several of its points had undergone material change, or were no longer the same when visited after the lapse of fourteen years. These remarks refer particularly to islets situated within the lagoon. I could myself quote many instances of the same description.”—“Wilkes' Exploring Expedition,” vol. iv. p. 271.

^{page 513 note *} U. S. Ex. Exp., vol. iv. p. 269.

^{page 513 note †} Geol. Mag., Dec. 1877.

^{page 513 note ‡} Fuchs,Über die Entstehung der Aptychenkalke. Sitzb. der k. Akad. der Wissensch. 1877.

^{page 514 note *} This ledge and steep slope beyond where a depth of 30 or 40 fathoms was reached, was characteristic of a large number of atoll and barrier reefs, and seemed due to wave action. Experiments had been made with masses of broken coral, and it was found that these could (on account of their rough and jagged surface) be built up into a nearly perpendicular wall by letting them fall on each other. A talus formed in water deeper than 40 fathoms where there was little if any motion would be different from one formed on land. In the latter case the disintegrating forces at work always tended to set the talus in motion; in the former case everything tended to consolidate and to fix the blocks in the positions first assumed. A removal of lime in solution would take place from the blocks forming this steep slope, but, except in very deep water, this would not be sufficient to check the outward extension of the reef.

^{page 515 note *} A dredging in 155 fathoms, close to the barrier reef of Australia (between it and Raine Island), gave a coral sand, which was, I estimate, more than two-thirds made up of the shells of surface animals.

^{page 515 note †} Hence in barrier reefs, where the depth outside is very great, we find the reefs running closer to the shore than where the depth is less, and consequently the talus to be formed is smaller.

^{page 516 note *} Voyage of the Fly, vol. i. p. 335.

^{page 516 note †} Dana's Corals and Coral Islands, p. 345. Couthouy's “Remarks on Coral Formations,” Bost. Jour. Nat. Hist. See also Stutchbury, West of England Journal.

^{page 516 note ‡} Very strong currents run out of the entrances into lagoons and lagoon channels, and when the tow-net was used in these entrances it showed that a large quantity of coral detritus was being carried seawards.

^{page 517 note *} “We may conclude that immense areas have subsided, to an amount sufficient to bury not only any formerly existing lofty table-land, but even the heights formed by fractured strata and erupted matter.”—“Coral Reefs,” p. 190.