188 ARTHROPODA 



Find: 



1. Into what regions can the body be divided? 



2. The eyes, the eye spot, and the two pairs of small an- 

 tennae. 



3. The sucking proboscis, composed of mandibles and 

 maxillae, which lies between the suckers. 



4. The suckers, which are the modified second maxillae. 



5. The posterior (third) maxillipeds just behind the 



suckers. 



6. Four pairs of biramous thoracic appendages. What is 



their function? 



Make a drawing of the animal. 



Wilson: The Fish Parasites of the Genus Argulus Found in the Woods 

 Hole Region. Bull. U. S. Bur. Fish., 24, 1904. 



LEPAS (Goose Barnacle) 



If possible, examine a cluster of specimens as they natu- 

 rally occur attached to floating timber. 



1. Account for the fact that the peduncles are much larger 

 in some specimens than in others. Are they contractile so 

 the body may be moved into different positions? Would 

 such movements be of value? 



2. Notice the thoracic appendages. Can they be thrust 

 from the shell? What is their character? What are their 

 characteristic movements? Drop a small piece of clam meat 

 on these appendages of a living specimen and see what hap- 

 pens. What kind of food would they naturally collect? 



3. Examine the portions of the shell. The portion on the 

 closed margin is the carina, laterally and near the base of 

 the peduncle are the scuta, and near the extremity the terga. 

 Why are there so many pieces? Notice the lines of growth 

 and determine the direction of growth of each piece. 



Draw the animal as seen from one side. 



Carefully remove the carina and with a scalpel or razor 

 cut a preserved specimen into right and left halves, extend- 

 ing the cut through the peduncle. 



4. The mouth will be seen at the end of a rather thick 



