SKULL OF LOPHIOMYS.
The latter is perhaps the case with the curious little Rodent which alone forms the present family, of which its original describer, M. Alphonse Milne-Edwards, writes as follows:—“In its general aspect it somewhat resembles certain Opossums, and like these it is pedimanous;[52] but these are the only analogies it presents to the Marsupials, and in its dental system, as also in the rest of its organisation, we easily see that it belongs to the order Rodentia. It differs, however, from all the members of this group by characters of considerable importance; I may even say that, by some peculiarities of structure it departs from all other Mammals, and that we find in it anatomical arrangements of which we have hitherto had examples only in the class of Reptiles.” After an exhaustive discussion of the characters of this curious little animal, M. Milne-Edwards comes to the conclusion that it is most nearly related to the members of the following family, and especially to the Hamsters, although he found it impossible to unite it with them. In this course he has been followed by other writers.
LOPHIOMYS.
The general construction of the skull is the same as in the Muridæ, but from the temporal ridges thin plates are developed, which bend downwards, and articulate with similar plates springing from the malar bones, and thus completely arch over the temporal fossæ after a fashion only met with in certain reptiles, and especially in the Hawksbill Turtle (Chelone caretta). The whole upper surface of the skull is covered with minute but perfectly definite granules, arranged with much regularity, and these, which occur in no other Mammal, give the skull a very peculiar aspect, such as may be seen in some fishes. As in the Muridæ, there are three molars on each side in each jaw, and these are rooted and strongly tubercular; the foremost in each series having three and the others each two ridges. Without entering in detail into the peculiarities described at great length by M. Milne-Edwards, we may say that in its general structure, and especially in that of the skeleton, the animal is murine, but with a very important distinction, namely, that the collar bones, which are well developed in the Rats and their allies, are here reduced, as in the Hares and Rabbits, so as to form only two small bony styles freely suspended among the muscles, and that the first toe in the hind feet, although not very long, is so attached as to be opposite to the rest, thus converting the organ into a prehensile hand which the animal uses freely in climbing. The cæcum is small.
In its external characters this animal is as remarkable as in its anatomical structure. In general appearance, as stated by its describer, it has much resemblance to a small Opossum, but the bushy tail and the peculiar arrangement of the hair on the body are met with in no Marsupials. The head is small; the general form stout; the limbs short, and the hind ones not much longer than their fellows; and the ears are of moderate size and sparingly clothed with hair. The prevailing colour is blackish-brown, but a triangular spot on the forehead, a streak under each eye, and the tip of the tail, are white; and the long hairs which clothe the body and tail are dark only in the middle, the base and tip being white, as are also a great quantity of finer and shorter hairs which form a sort of under fur. But the chief peculiarity of the coat is to be found in the arrangement of the hairs of the body. The long hairs of the middle of the back and tail, some of which are nearly three inches in length, are capable of being raised into a nearly upright position, forming a sort of crest which gives the animal a very peculiar aspect, and this crest is separated from the pendulous hair of the flanks by a sort of furrow clothed with very peculiar hair of a greyish-tawny colour. These hairs are unlike any others known to occur among Mammals. The apical part is of the ordinary construction; but the following portion down to the base is “very rugose, and presents a spongy aspect, due to the interlacing, and, so to speak, felting of a multitude of epidermic filaments emanating from radiate cells, which constitute a perfect network of irregular meshes. Within the sort of sheath thus formed longitudinal filaments which break up into bundles of fibrils are to be seen.”
Very little is known as to the habitat of this animal, which M. Milne-Edwards has named Lophiomys Imhausi, the former name referring to the crested character of the back, the second commemorating the person who first brought the creature to the notice of naturalists. M. Imhaus, stopping for a few hours at Aden on his way home from Réunion, saw a living specimen of this Rodent in the possession of a negro from whom he bought it, but could learn nothing as to its origin. He inferred, however, that it had not been brought very far, and that its native country was either Southern Arabia, or some region in Abyssinia, or Nubia, on the other side of the Red Sea. This specimen was brought to France, and lived for about a year and a half in the Garden of Acclimatization in the Bois de Boulogne, where it fed upon maize, vegetables, and bread, slept during the day, and climbed with ease upon chairs and other convenient objects by the aid of its hinder hands. It never took its food in the fore-paws to carry it to the mouth as so many Rodents do. When irritated it elevated the crest right down to the end of the tail, and defended itself by biting vigorously.
It is doubtful whether the Lophiomys inhabits Arabia, but it is found in the neighbouring parts of Africa. Professor Peters described the skull of the animal as representing a new generic type under the name of Phractomys æthiops. His specimen was obtained by Dr. Schweinfurth from the tombs of Maman, north of Kassala, in Upper Nubia. A third specimen has been brought from Keren in the Bogos country, and a fourth from the Erkanid mountains between Suakim and Singat.
MOLAR TEETH OF THE BLACK RAT.