194 THE HAUNTS OF LIFE 



actual fossils have been found, as they have no 

 hard parts which could have been preserved, 

 yet we have evidence of the existence of worms 

 in the remote past "by the discovery of the 

 trails which they have left in crawling over 

 soft mud, now hardened into shale or slate, or 

 by the burrows which they made in sand, which 

 has now been converted into sandstone and 

 quartzite. . . ." "Worm-burrows and trails 

 are among the oldest fossils yet discovered." 



FIG. 19. PERIPATUS. 

 A primitive Air-breather, antecedent to Centipedes and the like. 



The second great invasion was that of the 

 Air-Breathing Arthropods, led by simple 

 jointed-footed animals, well represented by 

 a "living fossil," called Peripatus, an old- 

 fashioned creature, surviving from a very 

 different world. Peripatus is a beautifully 

 coloured soft-bodied animal, worm-like in 

 shape, but with simple stumpy limbs, with' 

 antennae on the head, and two pairs of mouth- 

 parts. It lives chiefly in rotting wood, and 

 comes out only at night. When it is handled it 



