Taking the above in the order here given, we have, first, two peculiar genera of true flycatchers, a family confined to the Old World, but extending over the Pacific as far as the Marquesas Islands. Next we have two peculiar genera (with four species) of honeysuckers, a family confined to the Australian region, and also ranging over all the Pacific Islands to the Marquesas. We now come to the most important group of birds in the Sandwich Islands, comprising seven or eight peculiar genera, and twenty-two species which are believed to form a peculiar family allied to the Oriental flower-peckers (Diceidæ), and perhaps remotely to the American greenlets (Vireonidæ), or
tanagers (Tanagridæ). They possess singularly varied beaks, some having this organ much thickened like those of finches, to which family some of them have been supposed to belong. In any case they form a most peculiar group, and cannot be associated with any other known birds. The last species, and the only one not belonging to a peculiar genus, is the Hawaiian crow, belonging to the almost universally distributed genus Corvus.
On the whole, the affinities of these birds are, as might be expected, chiefly with Australia and the Pacific Islands; but they exhibit in the buzzard, one of the owls, and perhaps in some of the Drepanididæ, slight indications of very rare or very remote communication with America. The amount of speciality is, however, wonderful, far exceeding that of any other islands; the only approach to it being made by New Zealand and Madagascar, which have a much more varied bird fauna and a smaller proportionate number of peculiar genera. The Galapagos, among the true oceanic islands, while presenting many peculiarities have only four out of the ten genera of Passeres peculiar. These facts undoubtedly indicate an immense antiquity for this group of islands, or the vicinity of some very ancient land (now submerged), from which some portion of their peculiar fauna might be derived. For further details as to the affinities and geographical distribution of the genera and species, the reader must consult Mr. Scott Wilson's work The Birds of the Sandwich Islands, already alluded to.
Reptiles.—The only other vertebrate animals are two lizards. One of these is a very widespread species, Ablepharus pœcilopleurus, ranging from the Pacific Islands to West Africa. The other is said to form a peculiar genus of geckoes, but both its locality and affinities appear to be somewhat doubtful.
Land-shells.—The only other group of animals which has been carefully studied, and which presents features of especial interest, are the land-shells. These are very numerous, about thirty genera, and between three and four hundred species having been described; and it is remarkable that this single group contains as many species of
land-shells as all the other Polynesian Islands from the Pelew Islands and Samoa to the Marquesas. All the species are peculiar, and about three-fourths of the whole belong to peculiar genera, fourteen of which constitute the subfamily Achatinellinæ, entirely confined to this group of islands and constituting its most distinguishing feature. Thirteen genera (comprising sixty-four species) are found also in the other Polynesian Islands, but three genera of Auriculidæ (Plecotrema, Pedipes, and Blauneria) are not found in the Pacific, but inhabit—the former genus Australia, China, Bourbon, and Cuba, the two latter the West Indian Islands. Another remarkable peculiarity of these islands is the small number of Operculata, which are represented by only one genus and five species, while the other Pacific Islands have twenty genera and 115 species, or more than half the number of the Inoperculata. This difference is so remarkable that it is worth stating in a comparative form:—
| Inoperculata. | Operculata. | Auriculidæ. | |
| Sandwich Islands | 332 | 5 | 9 |
| Rest of Pacific Islands | 200 | 115 | 16 |
When we remember that in the West Indian Islands the Operculata abound in a greater proportion than even in the Pacific Islands generally, we are led to the conclusion that limestone, which is plentiful in both these areas, is especially favourable to them, while the purely volcanic rocks are especially unfavourable. The other peculiarities of the Sandwich Islands, however, such as the enormous preponderance of the strictly endemic Achatinellinæ, and the presence of genera which occur elsewhere only beyond the Pacific area in various parts of the great continents, undoubtedly point to a very remote origin, at a time when the distribution of many of the groups of mollusca was very different from that which now prevails.
A very interesting feature of the Sandwich group is the extent to which the species and even the genera are confined to separate islands. Thus the genera Carelia and Catinella with eight species are peculiar to the island of Kaui; Bulimella, Apex, Frickella, and Blauneria, to Oahu; Perdicella to Maui; and Eburnella to Lanai.
The Rev. John T. Gulick, who has made a special study of the Achatinellinæ, informs us that the average range of the species in this sub-family is five or six miles, while some are restricted to but one or two square miles, and only very few have the range of a whole island. Each valley, and often each side of a valley, and sometimes even every ridge and peak possesses its peculiar species.[[125]] The island of Oahu, in which the capital is situated, has furnished about half the species already known. This is partly due to its being more forest-clad, but also, no doubt, in part to its being better explored, so that notwithstanding the exceptional riches of the group, we have no reason to suppose that there are not many more species to be found in the less explored islands. Mr. Gulick tells us that the forest region that covers one of the mountain ranges of Oahu is about forty miles in length, and five or six miles in width, yet this small territory furnishes about 175 species of Achatinellidæ, represented by 700 or 800 varieties. The most important peculiar genus, not belonging to the Achatinella group, is Carelia, with six species and several named varieties, all peculiar to Kaui, the most westerly of the large islands. This would seem to show that the small islets stretching westward, and situated on an extensive bank with less than a thousand fathoms of water over it, may indicate the position of a large submerged island whence some portion of the Sandwich Island fauna was derived.