318 INSECTIVORES. 
in accordance with their purely terrestrial and non-fossorial habits. And the 
broad first and second molar teeth of the upper jaw are characterised by having 
five distinct cusps, of which the central one is very small, and connected with 
the two inner ones by a pair of oblique ridges. 
THE HEDGEHOGS. 
Genus Hrinaceus. 
The European hedgehog, or urchin, which is far the largest of the British 
Insectivores, is the best known representative of a somewhat extensive genus 
distributed over the greater portion of Europe, and parts of Africa and Asia, 
although unknown in Madagascar, the Malayan Peninsula and Islands, Burma, 
Siam, Southern China, and Siam. 
The essential characteristics of the hedgehogs, as distinct from the gymnuras, 
are to be found in the dense coat of short spines covering the back and sides of 
the body, and also the shortness of the tail. The hedgehogs have 36 teeth, of 
which, on each side, 3 are incisors, + canines, and § cheek-teeth. An examination 
of the skull will show that the first pair of front or incisor teeth in the upper jaw 
have remarkably long crowns, which are widely separated from one another in 
the middle line; while the two remaining incisor teeth on each side of the same 
jaw are much smaller. It will further be observed that the middle region of 
the palate of the skull contains some open spaces not occupied by bone. The 
common hedgehog (Hrinaceus ewropeus) is characterised by the short and almost 
imperceptible neck, the pig-like snout, from which it derives its popular name, 
and also by the shortness of its limbs. Exclusive of the short naked tail, 
which measures about 1} inches, an average-sized hedgehog is about 10 inches 
in length. The great peculiarity of all the hedgehogs is the power they possess 
of rollmg themselves up into a ball-like form, presenting a chevaua-de-frise 
of spikes, impenetrable to the great majority of other animals. This rolling-up 
process is effected by the aid of an extraordinary development of a layer of 
muscles found beneath the skin of most Mammals, and known as the paniculus 
carnosus. When rolled up, the head and feet are tucked inwards, so that only the 
spines are exposed; and it requires a bold dog or fox to attack a hedgehog 
when in this condition. Under the microscope the spine is seen to be marked 
by a number of parallel longitudinal grooves; the ridges between them being 
ornamented, in some of the foreign species, with rows of tubercles. Hedgehogs 
date from a remote antiquity; and it is doubtless solely due to this protective 
armour of spines that animals of such low organisation and of such comparatively 
large size have been enabled to survive without resorting to the protection afforded 
by a subterranean or aquatic mode of life. 
The food of the European hedgehog is very varied, including 
insects, worms, slugs, snails, lizards, snakes, birds’ eggs, rats, mice, and 
other small animals ; while roots and fruit are also consumed to a certain extent. 
The partiality of hedgehogs for insects is often taken advantage of in ridding 
houses of beetles and cockroaches; although the hedgehog itself not unfrequently 
Habits. 
