188 



ARTICULATES: CRUSTACEANS. 



with feather-like arms or feet, which they regularly 

 protrude and withdraw, a sort of grasping motion as 

 though they would secure any little animals or parti- 

 cles of food that might be within their reach. Some 

 kinds of Acorn-Barnacle completely cover the rocks 

 between high and low water mark; others delight in 

 deep water. In long voyages barnacles sometimes be- 

 come so numerous on the bottom of a vessel as to seri- 

 ously hinder its progress. Although in the adult state 

 Barnacles or Cirripeds are fixed and stationary, the 

 young swim freely about. 



Fig. 35 1 . Duck Barnacle. Fig. 353. Horse-shoe Crab. 



The Horse-shoe Crab is found in all seas. 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. 



