The Rhynchocyon, which is a very rare animal in collections, appears from the description and figure of Professor Peters to be a queer-looking beast. It measures about eight inches in length, exclusive of the tail, which is rather long, tapering, and rat-like, being covered with a ringed skin, and furnished with only a few scattered hairs. The muzzle is produced into a very long movable snout. The fur is of a rusty-brown colour, with a blackish tinge about the ears and the back of the head, and some light reddish spots on the hinder part of the back.
This animal, which is called Mutâu by the natives, lives in holes in the ground, from which it issues at night in search of the insects on which it feeds, and is chiefly interesting to the zoologist for the structural characters which it presents. Thus, whilst agreeing with the ordinary members of the present family sufficiently to warrant its being classified with them, and to prevent its going anywhere else, it differs from them in some exceedingly important particulars, which might almost justify its being placed in a family by itself. Although the hind legs are more developed than the fore limbs, the disproportion between them is hardly so great as in the true Jumping Shrews; and further, all the feet are reduced to the same four-toed condition as the hind feet in the Petrodrome, and the outer toe is shorter than the rest. But it is in the dentition that the anomaly is the greatest. The Rhynchocyon never has more than one small incisor tooth on each side in the upper jaw, and even this drops out as the creature advances in age; and the upper canine is a simple tooth with a single root. In the lower jaw there are three incisors on each side, and in both jaws the canines are followed by three premolars and three molars. In the hind legs the two shank-bones are united near the extremity as in the preceding species, but the two bones of the fore-arm (radius and ulna) are separate.
RHYNCHOCYON.
FAMILY IV.—ERINACEIDÆ, OR HEDGEHOGS.
We pass now from groups of insect-eating animals the members of which must be sought in far distant countries, to a family represented in England by a very well-known species. Our Common Hedgehog, in fact, may serve as an excellent example of the family to which it belongs, although this certainly includes one species which presents rather anomalous characters.
All the Erinaceidæ have the two molar teeth broad, as in the preceding families; in fact, here the hinder ones are nearly square, and the tubercles forming their upper surface are rounded in form. The skull has a complete zygomatic arch, and the tympanic bone forms a bubble-like swelling on each side of the back of the skull. The back is clothed with hairs, among which there are a number of strong spines or bristles. The legs are short, and formed exclusively for walking, and the hind legs have the two bones of the shank (tibia and fibula) united. The intestine has no cæcum.
These animals are confined to the Old World, in nearly all parts of which some of the species are to be found. They feed chiefly upon insects and other small animals; most of them have the power of rolling themselves up into a ball, when the prickles with which the back is armed constitute a most formidable defensive armour; and in cold countries they pass the winter in a state of torpidity. Several fossil species have been found in Tertiary deposits in Europe.
THE HEDGEHOG.[261]
Our Common English Hedgehog may serve as the type of this family; all the species of which, with only a single exception, belong to the same genus, and present a very close resemblance to each other, both in appearance and habits. All the Hedgehogs, in fact, are small animals of robust form, with very short tails, and the greater part of the hairs of the upper surface converted into sharp spines. The muzzle is conical, and the jaws contain thirty-six teeth, twenty of which are in the upper and sixteen in the lower jaw (see figure, [p. 343]). The arrangement of these teeth is peculiar. There are three incisors on each side, of which the inner one is considerably larger than the rest, and in the upper jaw these are separated by a small space from the next tooth, which is generally regarded as a premolar, in which case the animals have no canines. Behind this, in the upper jaw, are three premolars, gradually increasing in size until the third has very much the appearance of a true molar, but furnished with a cutting edge; and then three molar teeth, two of which are large and broad, nearly square, and crowned with very strong tubercles, admirably adapted for crushing the hard skins of the insects on which the Hedgehogs principally feed. The hindmost molar is a small tooth. In the lower jaw the innermost incisor is very large, and projects almost horizontally forward, and it is followed by three small teeth, the nature of which has been a matter of dispute. Two of them, however, are generally considered to be incisors, and the third a premolar, but by M. F. Cuvier they were all described as premolars, making, with another and larger tooth which follows them, four premolars in the lower as in the upper jaw, This last premolar is a carnassial or cutting tooth, corresponding to that in the upper jaw. It is separated by a small space from the last of the smaller anterior teeth, and is followed by three true molars, two of which are large, and furnished with four or five sharp tubercles, while the third is small, and shows only one strong point.