356 THE LIVING ANIMALS OF THE WORLD 



A comparatively small 

 number of these moss-animals 

 are inhabitants of fresh-water, 

 forming brown tubular aggre- 

 gations on the under side of 

 the leaves of water-lilies or 

 other submerged objects. It 

 is interesting to observe that 

 the tentacular crown in almost 

 all these fresh-water species 

 is horseshoe-shaped, instead ^f 

 like a shuttle-cock, as in the 

 marine forms. One very not- 

 able fresh-water species is re- 

 markable for the circumstance 

 that in place of horny tubes 

 the component individuals 

 secrete a common trail-parent 

 gelatinous matrix, which is 

 provided with a crecping-ba-e, 

 wherewith the colony-stock is 

 enabled to travel over the 



surfaces of the water-plants among which it lives, or up the glass sides of an aquarium. 



In some respects, and more especially their earlier developmental phases, the Moss animals 



show affinities with the Lamp-shells, while the tentacular crown of the adult individual is 



closely imitated in certain worms. 



!*/ 



MOSS-ANIMALS 



Tkeie coral-Hie masses are tomfoied of man? thousand closely united dwelling- 

 cells of microscopic dimension! 



CHAPTER V 



H'ORMS 



THE WORMS and their allies embrace a numerous assemblage of animals which exhibit a 

 remarkable amount of variation both in structure and habits. A fundamental distinction 

 which serves to separate readily even the most highly organised members of the group 

 from the other articulate or jointed-bodied animals, such as Crabs, Insects, or Centipedes 

 is furnished by the character of the locomotive appendages. These in the Worm Tribe never 

 assume a jointed character, but take the form of unjointed membranous processes which maj- 

 or may not be supplemented by bristles. Frequently bristles alone constitute the essential 

 locomotive organs. In certain groups, such as the Leeches, Flat-worms, Thread-worms, and 

 others, even these are unrepresented. 



The appropriate title of BRISTLK-WOUMS has been conferred upon the section in which 

 the locomotive organs take the form of bristles. Among tlie-e the COMMON KAKTII-WOKM is 

 included. At first sight the worm's body appears to be perfectly smooth and naked; it 

 is found, however, on closer investigation to be furnished, according to the species, with 

 either two or four longitudinal rows of fine, hook-like bristles. Although these bristles 

 project but slightly above the surface of the skin, they constitute very effective aids to 

 locomotion, enabling the animal to obtain a secure grip upon the surface of the ground 

 over which it may be traveling. Progression under such conditions is effected, in fact, on 

 the same principle as that of the snake, the ends of the stiff bristles with which the segments 

 are armed fulfilling the same role as the projecting edges of the reptile's scales. I.arth- 

 worms are chiefly vegetable-feeders, dragging into their holes fallen leave-;, straws, and every 



