The ocean depths by which these islands are separated from the nearest continents are enormous. North, east, and south, soundings have been obtained a little over or under three thousand fathoms, and these profound deeps extend over a large part of the North Pacific. We may
be quite sure, therefore, that the Sandwich Islands have, during their whole existence, been as completely severed from the great continents as they are now; but on the west and south there is a possibility of more extensive islands having existed, serving as stepping-stones to the island groups of the Mid-Pacific. This is indicated by a few widely-scattered coral islets, around which extend
considerable areas of less depth, varying from two hundred to a thousand fathoms, and which may therefore indicate the sites of submerged islands of considerable extent. When we consider that east of New Zealand and New Caledonia, all the larger and loftier islands are of volcanic origin, with no trace of any ancient stratified rocks (except, perhaps, in the Marquesas, where, according to Jules Marcou, granite and gneiss are said to occur) it seems probable that the innumerable coral-reefs and atolls, which occur in groups on deeply submerged banks, mark the sites of bygone volcanic islands, similar to those which now exist, but which, after becoming extinct, have been lowered or destroyed by denudation, and finally have altogether disappeared except where their sites are indicated by the upward-growing coral-reefs. If this view is correct we should give up all idea of there ever having been a Pacific continent, but should look upon that vast ocean as having from the remotest geological epochs been the seat of volcanic forces, which from its profound depths have gradually built up the islands which now dot its surface, as well as many others which have sunk beneath its waves. The number of islands, as well as the total quantity of land-surface, may sometimes have been greater than it is now, and may thus have facilitated the transfer of organisms from one group to another, and more rarely even from the American, Asiatic, or Australian continents. Keeping these various facts and considerations in view, we may now proceed to examine the fauna and flora of the Sandwich Islands, and discuss the special phenomena they present.
| The light tint | shows | where | the sea is | less than 1,000 fathoms deep. |
| The dark tint | ,, | ,, | ,, | more than 1,000 fathoms deep. |
| The figures show the depths in fathoms. | ||||
Zoology of the Sandwich Islands: Birds.—It need hardly be said that indigenous mammalia are quite unknown in the Sandwich Islands, the most interesting of the higher animals being the birds, which are tolerably numerous and highly peculiar. Many aquatic and wading birds which range over the whole Pacific visit these islands, twenty-five species having been observed, but even of these six are peculiar—a coot, Fulica alai; a moorhen, Gallinula galeata var sandvichensis; a rail with rudimentary wings, Pennula millei; a stilt-plover, Himantopus knudseni; and
two ducks, Anas Wyvilliana and Bernicla sandvichensis. The birds of prey are also great wanderers. Four have been found in the islands—the short-eared owl, Otus brachyotus, which ranges over the greater part of the globe, but is here said to resemble the variety found in Chile and the Galapagos; the barn owl, Strix flammea, of a variety common in the Pacific; a peculiar sparrow-hawk, Accipiter hawaii; and Buteo solitarius, a buzzard of a peculiar species, and coloured so as to resemble a hawk of the American subfamily Polyborinæ. It is to be noted that the genus Buteo abounds in America, but is not found in the Pacific; and this fact, combined with the remarkable colouration, renders it almost certain that this peculiar species is of American origin.
The Passeres, or true perching birds, are especially interesting, being all of peculiar species, and, all but one, belonging to peculiar genera. Their numbers have been greatly increased since the first edition of this work appeared, partly by the exertions of American naturalists, and very largely by the researches of Mr. Scott B. Wilson, who visited the Sandwich Islands for the purpose of investigating their ornithology, and collected assiduously in the various islands of the group for a year and a half. This gentleman is now publishing a finely illustrated work on Hawaiian birds, and he has kindly furnished me with the following list.
Many of the birds recently described are representative forms found in the several islands of the group.