tell him to apply his knowledge of the mode of extracting tin ore from his own gravel to the drift and debris on the flanks of the great north and south chains of Australia, or any smaller parallel ridges of that great country;* for great would be my pleasure to learn, that through the application of Cornish skill, such a region should be converted into a British "El Dorado."

Requesting you to pardon this little digression, which, after all, may be turned to profit, and hoping that you will be as proud as I am of the connection which is now established between Cornwall and Siluria, believe me to be, my dear Sir Charles, yours most faithfully,

ROD. I. MURCHISON.

Geographical Distribution of Zoophytes. By JAMES D. DANA.

Heat, light, pressure, and means of subsistence, influence more or less the distribution of all animals; and to these causes should be added, for water species, the nature or condition of the water, whether fresh or marine, pure or impure, still or agitated. Next to the character of the water, heat is the most prominent limiting agent for marine animals, especially as regards latitudinal extent; while light and hydraulic pressure have much influence in determining their limits in depth.

Although these causes fix bounds to species and families, they do not necessarily confine tribes of species to as small limits. This is sometimes the case, and it is nearly true of a large group of zoophytes; yet other tribes and orders include species whose united range comprises all the zones, from the equator to the polar ices, and every depth, to the lowest which man has explored, affording traces of life.

Order Hydroidea.-The Hydroidea are met with in all seas, and at great depths, as well as at the surface. The tropics, and the cold water of the frigid zone, have their peculiar species, and a few are found in fresh waters. The rocks and common marine plants of the sea-coast, the shell, or the floating fucus of the ocean, are often covered with these feathery corals; and about reefs they occasionally

dead or living

* It appears that gold ore has been also found in the metalliferous ridges of South-western Australia (Adelaide, &c.).

implant themselves upon the dead zoophyte, forming a mossy covering, taking the place of the faded coral blossom.

The species are most abundant, however, in the waters o the temperate zone, and are common upon some portions of our own coast.

Order Actinoidea. The Actinoidea are marine zoophytes. All oceans have their species, yet in the torrid zone they more especially abound, and display most variedly their colours and singular forms.

zone.

The soft Actinidæ and the Alcyonaria have the widest range, occurring both among the coral reefs of the equatorial regions, and to the north and south beyond the temperate The Mediterranean affords species of Gorgonia, Corallium, and Alcyonium, besides numerous Actinoidea. The coasts of Britain have also their Alcyonia and Actinia; and from far in the northern seas come the Umbellularia, and some other species of the Pennatula family.

Among the coral-making Actiniaria, the Madrepore and Astræa tribes are almost exclusively confined to the coral-reef seas, a region included mostly between the parallels of 28° north and south of the equator, while the Caryophyllia family are spread as widely as the species of Actinia. Several species of Caryophyllidæ occur in the Mediterranean, and others in the high northern seas, and they are met with at depths of several hundred feet. They are also common. among the coral reefs of the tropics.

The Madreporacea and Astræacea, with the Gemmiporidæ, are the principal constituents of coral reefs. The temperature limiting their geographical range is 66° or 68° F., this being the winter temperature of the ocean on the outskirts of the reef-growing seas. The waters may sometimes sink to 64°, but this appears to be a temperature which they can endure, and not that in which they germinate. The extremes which they will survive prove only their powers of endurance, and do not affect the above statement; for their geographical distribution will be determined by the temperature which limits their powers of germination.

The temperature of the ocean in the warmest parts of the Pacific varies from 80° to 85°, and here Astræas, Meandri

nas, Madrepores, &c., are developed with peculiar luxuriance, along with thousands of other strange and beautiful forms of tropical life. A range from the above temperature to 72° does not appear to be too great for the most fastidious species. At the Sandwich Islands, which are near the northern limits of the coral seas, Porites and Pocilloporæ prevail, and there are very few species of the genera Astræ, Mussa,* and Meandrina, which are common nearer the equator.

The range of these reef-forming corals in depth is singularly small. Twenty, or perhaps sixteen, fathoms will include very nearly all the species of the Madrepore and Astræa tribes. Temperature has little or no influence in occasioning this limit, as 68° F. will not be found under the equator short of a depth of 100 fathoms. Light and pressure-the latter affecting the amount of air for aëration, are probably the principal causes. The waves, moreover, cannot aid in renewing the expended air below, as they do at the surface.

In recapitulation, we state, that the Astræacea, Madreporacea and the Gemmiporidæ among the Caryophyllacea, are, with few exceptions, confined to the coral-reef seas, and to within 20 fathoms of the surface. The Caryophyllidæ§ extend from the equator to the frigid zone, and some species occur at a depth of 200 fathoms or more. The Alcyonaria have an equally wide range with the Caryophyllidæ, and probably reach still farther towards the poles. The Hydroidea range from the equator to the polar regions, but are most abundant in the waters of the temperate zone.

Besides the above mentioned limiting causes, there are others of importance, one of which may be alluded to in this place; the remaining, belonging more properly to the Geological Report on Coral Reefs and Islands, will be particularly considered in the forthcoming volume by the author. The

* Lobophyllia of Blainville, Mussa of Oken.

†The evidences on this point will be presented in the Report on Coral Islands.

The exceptions belong mostly to the genus Euphyllia, which includes the genus Flabellum, some Turbinaliæ, and the Lobophyllia, having entire lamellæ. § The Caryophyllic of Blainville, with the Dendrophylliæ, Oculinæ, &c.

cause referred to is that proceeding from original sites or centres of distribution. There is sufficient evidence that such centres of distribution, as regards zoophytes, are to be recognised, The species of corals in the West Indies are, in many respects, peculiar, and not one can with certainty be identified with any of the East Indies. The central parts of the Pacific Ocean appear to be almost as peculiar in the corals they afford. But few from the Feejees have been found to be identical with those of the Indian Ocean. A more complete acquaintance with the corals of these different seas, will undoubtedly multiply the number of identical species; but observations thus far made, seem sufficient to establish as a fact, that a large part of zoophytes are confined to a small longitudinal range. This will be seen from the following table, exhibiting, in a general manner, as far as known, their geographical distribution. Each column gives the number peculiar to the region specified at top:

The Pocilloporæ, Sideroporæ, Milleporæ, Favosites, and other genera of Madreporacea, in which the cells are internally divided by horizontal septa. † Part of the Porites of authors, the species having shallow cells closed at

From this table it appears, that only twenty-seven species out of 306 are known to be common to the East Indies and Pacific Ocean. With regard to those common to the East and West Indies, for which no column is arranged, there are but two, the Meandrina labyrinthica and Astrea galaxea, about which much doubt remains.

We have no authority for accrediting to the West Indies any species of the genera Fungia, Pavonia, Herpetolithus, Merulina, Monticularia, Gemmipora, Anthophyllum,* Pocillopora, Sideropora or Sericitopora, all of which are common in the opposite hemisphere. The Agaricia, with the excep- · tion of two osculant species, are confined to the sub-genus Mycedia, exclusively West Indian, which contains very firm compact corals, often with an Astree-like character. The Millepores are the only known Favositidæ, and but half a dozen Madrepores have yet been distinguished. The Manicinæ, Caryophylliæ, and Oculinæ, are more numerous in the West Indies than elsewhere, and the Ctenophyllia (Meandrinæ, with stout entire lamella), have been found only in the West Indies. The genus Porites contains several species, but they are uniformly more fragile and more porous than those I have seen from the Pacific and Indian Oceans; and the Polyps, as figured by Lesueur, are more exsertile, approaching in this particular, the Gonioporæ.—(American Journal of Science and Arts, Second Series, Vol. iii., No. 8, p. 160.)

Origin of the Hawaiian Nation.

All the Polynesians have clearly had one and the same parentage. Though their general resemblance in manners and customs, in religion and government, in appearance and dress, might be made to fill

bottom (Porites clavaria, and the allied). The other Parites, with a few exceptions, belong to the genus Manopora of the author, and are true Madrepores in their cells, but with imperfect calicles or none; the P. spumosa of Lamarck, and the allied, are here included, besides the Montipora of Blainville.

* Sarcinula in part of Blainville, Caryophyllia in part of Lamarck, Anthophyllum of Schweigger, who introduces the name, but not of writers on fossil

corals.