476 MAMMALIA. 



of year. From three to four young are born in May : they are 

 pinky white, with white quills, and both eyes and ears are 



Fig. 224. — Skull of Hedgehog (Brinaceus europaius). (NicliolsoD.) 



closed. They are joroduced and kept in a nest of moss, covered 

 with leaves. In many respects the hedgehog is injurious, but 

 it also does good in destroying vermin. 



Order CHIROPTEEA or BATS. 



The Bats, which are insectivorous mammals, are characterised 

 by the peculiarly modified forearms, adapted to form the 

 wings. The digits of the fore-limb are enormously elongated, 

 except the poUex. These fingers are united by a thin mem- 

 brane called the "patagium" (fig. 225, P), which is also ex- 

 tended between the fore and hind limbs and united to the sides 

 of the body. This expanded membrane is used for flight. The 

 poUex and first finger of the fore-limb may have a claw, but the 

 others are destitute of them. The hind-digits have each a long 

 nail. Bats have teeth of three kinds, and in all the canines are 

 well developed. The molars in the insectivorous bats are alwa3's 

 sharp pointed ; in the foreign fruit-eating bats they are tuber- 

 culate. The bones are never hollow as in birds. Two mammse 

 are placed upon the chest. The body is covered with hair, and 



