[447] Hylodes martinicensis affords another instance. Mon. Berl. Ac., 1876, p. 714.
[448] According to Mr. Boulenger, they measure from 6 to 10 mm. in diameter.
With regard to the interesting species, Ceratobatrachus guentheri, which forms the type of a new family, Ceratobatrachidæ, the same writer observes that it is remarkable for the numerous appendages and symmetrical folds which ornate its skin. It is, in fact, “all points and angles,” and may be truly termed a horned frog. There is great variation both in the coloration and in the integuments. “Out of the twenty specimens before me,” thus Mr. Boulenger writes, “no two are perfectly alike.” The development is presumed to be of the type in which the metamorphoses are hurried through within the egg. These horned frogs are very numerous in the islands of Bougainville Straits, and so closely do they imitate their surroundings, both in colour and pattern, that on one occasion I captured a specimen by accidentally placing my hand upon it when clasping a tree.
It is particularly important to notice not only that the Batrachians of the Solomon Islands, as far as we at present know, do not occur elsewhere, but also that in this region a distinct family has been produced. These facts support the conclusions deducible from the geological evidence that these islands are of considerable geological age (vide [page x.]). The insular and isolated conditions have been preserved during a period sufficiently extended for the development of a peculiar Batrachian fauna.
The modes of dispersal of frogs and toads, and, in truth, of the whole Batrachian class, are matters of which we are to a great extent ignorant. Frogs are usually stated to be absent from oceanic islands, a peculiarity of distribution which apparently accords with the circumstance that neither they nor their spawn can sustain submersion in sea-water. The occurrence, however, of three species of Cornufer in the Caroline and Fiji Islands, and of a species of Bato in the Sandwich Islands,[449] affects the general application of this conclusion. It may be suggested that these exceptions are due to human agency; but if so, it is difficult to understand why they have not been found in such a well explored island as New Caledonia.[450]
[449] Boulenger’s “Catalogue of the Batrachia Gradientia,” &c., 2nd edit., 1882.
[450] Perhaps the peculiar geographical distribution of the Batrachia may throw light on this subject. Ibid.
In concluding this chapter I will refer to the circumstance that my collections of the Reptiles and Batrachians of this large group have only in a manner broken ground in a region which promises the richest results to the collector. It cannot be doubted that in the elevated interiors of the large islands, such as those of Bougainville and Guadalcanar, there will be found a peculiar Reptilian and Batrachian fauna, the study of which will be of the highest importance for the furtherance of our knowledge of these geologically ancient classes of animals. I believe I am correct in stating that it was on account of the highly interesting Batrachian collections I sent to the British Museum, that I received a grant for further exploration from the Royal Society, which, however, I was unfortunately prevented from turning to account. The work has yet to be done, and there can be little doubt that the man who is first able to examine the lofty interior of such an island as Guadalcanar will bring back collections, the importance of which will amply recompense him for any hardship or personal risk he may have endured. My experience was confined to the sea-border and its vicinity. The future explorer will find his field in the mountainous interiors and on the highest peaks.
Note (April 19th, 1887).—Since I penned the above, further collections of reptiles and batrachians, made in these islands by Mr. C. M. Woodford, have been described by Mr. Boulenger at a recent meeting of the Zoological Society. I had the pleasure of meeting Mr. Woodford before he left England, and I hope that he has been able to accomplish his purpose of penetrating into the interior of one of the larger islands of the group.