Art. IX.—Note on the Rat that invaded Picton in March, 1884.
[Read before the Philosophical Institute of Canterbury, 5th May, 1887.]
Mr. James Rutland has kindly sent me four heads of this rat, and I have extracted the skull from one of them and compared it with one of Mus maorium from the sandhills at Shag River. The two agree in all essential points, but in the Picton rat the foramen magnum is rounded at the top, and the brain-case is relatively rather larger. Length of skull, 1.35 inch; width at zygomatic arch, 0.6; depth from palate, 0.415. Foramen magnum, height 0.17, width 0.22.
Mr. Meeson has given a good description of the rat, and has identified it, correctly I think, with Mus maorium.* The following additional particulars have been furnished me by Mr. Rutland.
The rat appears to have invaded Picton at the end of March, and to have suddenly disappeared by the 20th April. Old Maoris recognised it as the rat they used to eat in former times, and said that swarming on to the low lands periodically was always characteristic of it. Mr. Rutland says that a similar visitation, but on a smaller scale, occurred at Picton in 1878 or 1879.
These rats were often noticed climbing trees. In the Pelorus, where they stopped longer, they built nests, like birds, in trees. One in Mr. Rutland's possession had been constructed in the crown of a tree-fern, from dried leaves and the hairs of the fernfronds. They fed on green vegetables as well as on berries.
This rat is certainly different from Mus huegeli, Thomas, from Fiji (“Proc. Zool. Soc.,” 1880, p. 11), and I should think from M. exulans, Peale, also; but I have seen no full description of that species.
[Footnote] * “Trans. N.Z. Inst.,” vol. xvii., p. 199.