36 PRACTICAL ZOOLOGY. 



THE SOW-BUG. 



Sow-bugs are usually to be found under boards and 

 stones, and in other damp places. Get the largest speci- 

 mens for this study. 



1. The first part is the head, or carapace. 



2. Find and describe the eyes. 



3. What are the peculiarities of the antennae ? 



4. The jaws and maxillae are closely pressed together, 

 forming a short, blunt projection under the head. 

 The tip of this blunt proboscis is usually black. A 

 longitudinal groove shows the line of union of the 

 hinder maxillae. By pinching the body of a live sow- 

 bug, the mouth is sometimes more clearly shown by 

 the exudation of a liquid, as in the case of a grass- 

 hopper. 



Where is the line of division between the head and 

 thorax? Count the appendages which may be sup- 

 posed to belong to the head; how many rings do 

 these indicate? 



5. The line of division between the thorax and abdomen 

 is indicated by an abrupt change in the size of the 

 segments. How many segments has the thorax ? 



6. How many segments are there in the abdomen ? 



7. How many pairs of legs are there ? How many seg- 

 ments has each leg? Do the legs all extend in the 

 same direction? 



8 A series of thin, over-lapping plates under the abdomen 

 are the gills. In the anterior plates observe the white 

 air-chambers. Beginning at the foremost of these 

 gills, pick them apart with a -needle. Remove them 



