24 ARTHROPODS 



said to be specialised. Do you find any part or parts of the 

 leg specialized? If so, how are the parts specialized and 

 for what purposes? 



Make drawings of a first and third leg (X2). Mark the 

 specialized parts. 



(4) Look closely at the sternum of the thorax. How 

 many segments in it ? How are they joined together? How 

 does the number of segments compare with the number on 

 the dorsal side? Explain. The three front parts of the 

 sternum are called respectively the prosternum, the meso- 

 sternuMj and th^ metastermim. 



Make drawings of the sternum of the thorax, showing 

 the first two segments of the legs (X4)- 



Study the pleurum of the thorax. Do you find any other 

 markings beside the lines of division? 



Look above the second pair of legs, in the groove dividing 

 the mesothorax, and the metathorax for a light colored 

 rough spot. This is a spiracle or breathing pore, and is one 

 of the places where air enters the body. 



Look at it closely with a magnifying glass in a living 

 specimen and see it open and close as the animal breathes. 

 Look for another one of these on the front side of the meso- 

 thorax under the prothoracic collar. 



Make a drawing of the left side of the thorax showing 

 the points observed (X3)- 



(5) Get a fresh specimen and examine the wings. Move 

 the anterior wings out at right angles to the body. What 

 follows ? Why ? Note the place of attachment of the front 

 wings. How are they attached? Note the texture of the 

 anterior wings. They are called the tegmina, or wing 

 covers. Why should they be called wing covers? 



