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Show 1899.] ON THE MICE OF ST. KILDA. 77 Since then I have met with two instances of the same kind in the skulls of Marsupials. The first of these I detected in the skull of an apparently adult Macropus giganteus in the Museum of the Royal University of Ireland. In this case the bone was only recognizable on the right side as a distinct ossification, while on the left the suture between it and the lachrymal had disappeared. The second instance I found in the skull of an adult Wombat (Phascolomys platyrhinus) in the Natural History Museum of Queen's College, Belfast. Here the bone was well-developed on both sides of the skull, and distinctly separated by suture from the frontal, nasal, maxilla, and lachrymal. It is worthy of note that, in his memoir on the 'Modifications of the Skeleton in the Species of Phascolomys,' the late Sir Richard Owen does not seem to have recognized this pair of bones, notwithstanding that they are clearly displayed in more than one beautiful figure of the skull by his artist, Mr. Smit. The occurrence of such bones in Mammals so far removed from one another as a Lemur, a Hippopotamus, and two Marsupials suggests the probability of their being less uncommon in the mammalian skull than would at first appear, and I have little doubt that any naturalist who possesses the requisite time and opportunities for conducting the research in a large osteological museum would add to the list of such instances. 3. On the Species of the Genus Mus inhabiting St. Kilda. By G. E. H. BARRETT-HAMILTON, F.Z.S. [Received December 5, 1898.] (Plate IX.) The existence of any wild species of Mouse on the isolated rock of St. Kilda is an occurrence so apparently unlikely, that when in 1895 a specimen of a Mus sylvaticus-\\ke species was found amongst some examples of Mus musculus sent thence to the British Museum in spirit, it was received with an amount of surprise certainly equal to the importance of the discovery. The specimen, a young male, had been obtained aud was presented to the Museum by M r . J. Steele Elliott1. It was a very remarkable one, and bore unmistakable evidence of having come from an out of the way part of the world. Its characteristics were a larger foot and a smaller ear than the corresponding organs of typical Mus sylvaticus, while, what was no less noticeable, the very characteristic snow-white colour of the belly of our common Field-Mouse was in this individual replaced by a uniform rufous hue shading imperceptibly 1 Mr. Steele Elliott appears to have been the first person to collect specimens of the Mice of St. Kilda. The occurrence there of mice of some sort was, however, known previously to the outer world, and Seton states that " A cat is to be seen in almost every cottage, the mouse being the only wild animal on the island, and rats are still unknown " (' St. Kilda, Past and Present,' 1878, p. 132). |
