THE HEDGEHOG. 
353 
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. Tlius, 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 Bhynchocyon 
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 pre- 
ceding species, but the two bones of the fore-arm (radius and ulna) are separate. 
FAMILY IV.-ERINACEIDiE, 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 Erinaceidae 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 c&ecum. 
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.* 
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 vest, 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 pre- 
molars, 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 
* Erinaccus europcms. 
