Art. XXXVIII.—Note on the Maori Rat.
[Read before the Otago Institute, 24th October, 1876.]
In the collection obtained by Mr. Booth from the Maori cooking-places at Shag Point, were several skulls and other bones of the Maori Rat. These skulls differ considerably from those of Mus decumanus, and it is remarkable that they all have the teeth ground quite flat, exactly as in old Maori skulls.
These skulls resemble very closely the figure and description of the English Mus rattus given by Mr. Salter in the “Pro. Lin. Soc,” 1862, Zoology, p. 66; but they differ from it in the following particulars:—
They are much smaller. The nasal bones are not so obtuse at the anterior end; there is a slight process projecting backward from the anterior edge of the zygomatic fossa; the ridges on the frontal bones are widely bowed out and extend backward quite across the parietal bones, but become very small posteriorly; the foramen magnum is higher in proportion, and strictly pentagonal in outline; the foramen ovale is considerably larger than the foramen rotundum; the posterior nares are longer, a line from the front edge of the zygomatic arch crosses them slightly in front of the centre. (See Plate III.)
These differences appear to be sufficient to distinguish the Maori Rat from English specimens of Mus rattus. It will be interesting to compare these skulls with specimens of the Black Rat from Polynesia, for they will probably be found to be identical.
The following are the more important dimensions of the skulls from Shag Point:—
|Width at zygomatic arch||.85 "|
|Foramen magnum, height||.17 "|
|" " width||.23"|
The Black Rat described by Dr. Buller under the name of Mus novœ-zealandiœ,* and the one described by myself,† seem to be larger than the present specimens; they probably belong to the true Mus rattus.
I have compared the lower jaws of the rats from Shag Point with those from the Earnscleugh Cave, and I find them to be identical. The Earns-cleugh Cave rat is therefore not Mus decumanus, and the argument that I drew from the remains of these rats as to the recent age of the remains of Clangula finschi, Cnemiornis, and Dinornis in this cave,‡ falls to the ground.
[Footnote] * “Trans. N.Z. Inst.,” Vol. III., p. 1.
[Footnote] † “Trans. N.Z. Institute,” Vol. IV., p. 183.
[Footnote] ‡ “Trans. N.Z. Institute,” Vol. VII., p. 138.