[Read before the Philosophical Institute of Canterbury, 1st June, 1910.]
There are neither land - reptiles nor land - mammals indigenous to the Kermadec Islands, the group presenting in this respect one of the main features of oceanic islands. When the islands were discovered rats were plentiful, but reasons will be given below for considering them as introduced through the agency of man. Two marine animals—the green turtle and the humpback whale—regularly visit the group, while others are occasional visitors.
Mr. R. S. Bell, of Sunday Island, informed me that besides the green turtle one or two individuals of another species, probably the hawksbill, have been noticed from the shore. Mr. T. F. Cheeseman, F.L.S., F.Z.S., mentions a water-snake, which, from the description given him by Mr. T. Bell, he supposes to be Pelamys bicolor (Cheeseman, 1888).
On several occasions during September, 1908, I observed dolphins in Denham Bay, Sunday Island. Mr. Bell says that the sperm whale has been seen from the north coast of Sunday Island. On one occasion a portion, about 2 ft. long, of a large cuttlefish was cast up on Low Flat Beach. This fragment was possibly the remains of an animal which a whale had made a meal from, as it is known that sperm whales kill and eat these gigantic cephalopods.
The following notes are mainly from material gathered during a ten months' stay on Sunday Island, in 1908, as a member of the scientific expedition which originated with Mr. W. L. Wallace, of Timaru.
Chelone mydas. (Green Turtle.)
A large female specimen of the green turtle was shot by Mr. R. S. Bell off the rocks at the south end of Denham Bay on the 23rd May, 1908.
Turtles were noticed chiefly during the summer months—January to March—often as many as five or six being seen at one time. An observer standing on the shore at a little height can watch them browsing on a species of alga (Pterocladia capillacea), which grows abundantly on rocks in water down to about 5 m. in depth. Apparently, whilst in Sunday Island waters turtles eat no other kind of food. Every few minutes they come to the surface for a few seconds to breathe, but on the slightest alarm these timid reptiles swim swiftly away. They do not breed in the Kermadecs, but go north to warmer regions.
Megaptera boops. (Humpback Whale.)
A few humpback whales were noticed in Denham Bay in the latter part of August, 1908. During September their numbers increased, while in October and November they were common all round Sunday Island; at Macauley Island also, on 12th November, a large number were seen. They had their calves with them, and probably were migrating southwards. During their northward migration they are not seen from Sunday Island.
Mus exulans. (Pacific Rat.)
Specimens of the Pacific rat examined on Sunday Island agree in every particular with those from Funafuti, as described by Mr. E. R. Waite, F.L.S. (1897, p. 174), except that the under-surface, including inside of limbs, is light buff, or sometimes pale grey; fur pale grey at base; upper surface of feet light buff, hairs short; hairless parts of feet pink.
Skulls of Sunday Island examples appear to be proportionately more slender than the skull of the Funafuti specimen. The zygomatic arch is less prominent, thus giving a smaller breadth, whilst the nasal bones are narrower. These differences are apparent in the table of measurements given below, where the corresponding figures recorded by Mr. Waite for the Funafuti specimen are given for comparison.
Of thirty-four specimens of rats from Sunday Island of which I have measurements, I select the ten largest of each sex as best showing the size of full-grown individuals :—
|Head and Body.||Tail.||Length of Head.||Ear.||Forearm and Hand.||Hind Foot.|
Thus the male is, on an average, larger than the female. Apparently in the female the tail is proportionately longer than it is in the male; but this is probably due to the fact that the males are the more pugnacious, and consequently have their tails bitten more frequently. A large number of specimens collected for examination had to be rejected because more or less of the end of the tail was missing.
|" greatest breadth||3·5||3·5||3·4||3·5||3·6||4·0|
|Anterior palatinal foramina||5·5||6·5||5·7||5·7||6·4||5·7|
|Condyle to incisor-tip||21·5||22·5||22·5||23·0||24·4||23·0?|
|Coronoid-tip to angle||9·5||10·0||9·5||9·8||10·0||9·2|