MARINE WORMS. 49 



Marine Worms. A common form on the sea-shore 

 is Nereh (Fig. 52) ; the body is composed of from one to 

 two hundred joints, each of which bears a pair of paddles ; 

 upon the head are four eyes, while the mouth is armed 

 with a powerful proboscis and two large cimeter-like teeth. 



FIG. 52. Sea-worm (Nereis). (After Morse.) 



They live in holes in the sand, lined with a fluid secretion. 

 They multiply by eggs. The Cirratulus also lives in a tube. 

 In the South some of these forms arrange a leaf of sea- 

 weed in the structure so that it falls over the mouth, form- 

 ing a door, and giving the entire tube the appearance of 

 sea-weed. The Serpula (Fig. 53), that build stony houses, 

 have radiating coronets, dashed with rich coloring, for 

 breathing organs. The Pectinaria bears upon its head 

 a pair of combs of burnished gold, while with very few 

 exceptions all the worms are luminous green, blue, 

 white, and yellow lights marking their movements under 

 the sea. 



been estimated that they average about 100,000 to the acre. In 

 New Zealand 348.480 have been found in an acre of rich ground ; so 

 it will be seen that the upper crust is continually being eaten and 

 ejected by them, their myriads of holes conveying water to the interior 

 as well as air. The worms also drag vast masses of leaves under 

 ground, that enrich the soil. They cover up seeds, undermine rocks, 

 burying them up, and to their work is due the preservation of many 

 ruins and ancient works of art. Some of their casts found in India are 

 over a foot in length. In England, numbers of ancient Roman villas 

 have been discovered beneath the ground, their entombment, accord- 

 ing to Darwin, undoubtedly caused by the worms that undermined 

 them and deposited their casts upon the floors, until finally, aided by 

 other causes, they disappeared from sight, 



