THE WONDER OF LIFE 619 



and in the way these end in the hair-folhcle. There may- 

 be four hundred nerve-fibres to a single hair, so that if 

 there are twenty-five hairs on the chin region, there are 



Fio. 96. — ^King Crab, Limulus, seen from above. It is an archaic 

 type, a, veritable ' living fossil,' the sole survivor' of thejancient 

 race of Palseostraca. The figure shows the horseshoe-shaped 

 cephalothorax shield, bearing lateral and median eyes ; the ab- 

 dominal shield ; and a spear or telson projecting behind. (From 

 a specimen.) 



ten thousand nerve fibres. The vestigial hairs seem hke 

 speciaUzations of the tactile hairs or vibrissse which every 

 one knows in a cat's whiskers. In the toothless Cetaceans 



