202 



ARTHROrODS ; CRUSTACEANS. 



larly protrude and withdraw, — a sort of grasping 

 motion as tliough tlrey would secure any little animals 

 or particles of food that might be within their reach. 

 Some kinds of Acorn Barnacles completely cover the 

 rocks between high and low water mark ; others de- 

 light in deep water. In long voyages Barnacles some- 

 times become so numerous on the bottom of a vessel 

 as to seriously hinder its progress. Although in the 

 adult state Barnacles, or Cirripeds, are fixed and sta- 

 tionary, the young swim freely about 



Fig- 35I' — Duck Barnacle. 



Fig- 353- — Horseshoe Crab. 



The Horseshoe Crab is found on the Atlantic coast 

 of the United States and on tlie coast of Eastern Asia. 

 Some are two feet in length, and in all cases the body 

 ends in a sharp spine, which some of the savage tribes 

 use for spear points. This curious Crab walks and eats 

 with the same organs, — the lower part of the first six 

 pairs of legs being used for walking, and the upper 

 parts of the same legs being provided with teeth-like 

 organs, and used for jaws. 



