BIVALVE CRUSTACEANS AND BARNACLES. 



151 



rock. It will be much better to take them from the wooden 

 piers, or, if possible, specimens should be collected attached 

 to some pebble. These may now be placed in a jar or bowl 

 of salt-water ; and, if they are watched closely, there will be 

 seen a set of fringed arms, like hairs, thrust out at the top of 

 the shell, which, stretching out with graceful curves, close and 

 partly retract within the opening. This motion will be con- 

 stantly and rapidly repeated. There are six pairs of these 

 appendages, and they are flung out in this way to grasp the 

 minute particles in the water, which serve them as food. 

 The arms being jointed and fringed with delicate hairs, the 

 whole combined forms a sort of net. In Fig. 140, <7, the 

 tip of one of these arms is shown, highly magnified. 



Fig. 140.—^, Side-Tiew of Barnacle, Natural Size, showing Appendages protruded for Food; 

 B, Top-View of same closed ; C, hlghly-magniflcd View of the Tip of one of the Appendages. 



137. Inland pupils may break open the barnacles collected 

 on the oyster-shell, and, taking out the soft parts, may examine 

 them by placing the parts in water, when the fringed arms 

 become apparent ; and under the microscope the delicate hairs 



