THE HEDGEHOGS 321 



The more important of these characteristics are, however, of such a nature as to be 

 but briefly referred to in this place. It may be observed, however, that the brain 

 (as may be readily seen from the dimensions of its chamber in the dried skull) is 

 relatively smaller, and the union of the anterior elements of the pelvis in the middle 

 line on the inferior aspect of the body shorter, than in the preceding families. 

 Further, if the cavity for the eye in the dried skull be examined, it will be found 

 that there is not even a trace of any bony process to mark off its hinder limit frpm 

 the larger hollow containing the muscles that work the lower jaw. With the excep- 

 tion of one species, all the members of the family have five-toed feet, provided with 

 simple claws not adapted for digging ; this feature being in accordance with their 

 purely terrestrial and non-fossorial habits. And the broad first and second molar 

 teeth of the upper jaw are characterized 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. 



Genus Erinaceus 



The European hedgehog, or urchin, which is far the largest of the British In- 

 sectivores, is the best known representative of a somewhat extensive genus dis- 

 tributed over the greater portion of Europe, and parts of Africa and Asia, although 

 unknown in Madagascar, the Malayan Peninsula and islands, Burma, 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, f are incisors, \ canines, and f 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 

 {Erinaceus europ&us} is characterized 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 one and one- 

 half inches, an average-sized hedgehog is about ten inches in length. The great 

 peculiarity of all the hedgehogs is the power they possess of rolling themselves up 

 into a ball-like form, presenting a chevaux-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 



