236 OF URCHINS IN GENERAL. 



dered fixed, and capable of contracting. The 

 anterior move the head upward, and extend it 

 towards the back. The posterior raise the tail. 

 Those of the deep-seated layer elevate the head 

 and neck. The animal is then enabled to walk. 



"If the approach of danger induce the Urchin 

 to roll itself up, it accomplishes this in the follow- 

 ing manner: 



<e The orbicular cutaneus relaxes, and the muscles 

 of the head and neck elongate the oval; the deep 

 transverse fibres attached to the external portion 

 of the ventral cutaneus, render it broader. Every 

 thing now yields to the impulse: the flexors, and 

 the cutaneus of the neck and breast, draw the head 

 towards the belly : the cutaneus, and the muscles of 

 the abdomen, bring the tail and thighs towards the 

 head; the flexors of the limbs contract; the great 

 orbicular muscle then descends on the ribs, con- 

 tracts obliquely, and thus, assuming the shape of a 

 purse, retains the animal in a globular form*/' 



The Hedgehog is the only animal of the present 

 tribe that is an inhabitant of Europe. The other 

 six species are all natives of hot climates. Most of 

 them have a fetid and unpleasant smell. 



* Cuvier's Lectures on Comparative Anatomy, ii. p. 576581. 



THE 



