CHAPTER VII 

 BRANCH ARTHROPODA: ANIMALS WITH JOINTED LEGS 



THE WOOD-LOUSE OR SOW-BUG 



These curious creatures may be obtained in abundance 

 under boards and stones, especially in moist situations. 

 For this study, get as large specimens as you can find. 



I. — Notice the segmented character of the body. See if 

 you can easily distinguish the three divisions of the 

 body — head, thorax, and abdomen. 



II. — When the animal is viewed from above, the head is 

 what appears to be the first segment. Determine the 

 limits of the head by looking at it from both sides. 

 Notice its mode of attachment to the first segment of 

 the thorax. 



III. — To distinguish between the thorax and abdomen, look 

 for a place where there is a decided difference in the 

 size of two adjoining segments as seen from above. 

 How many segments has the thorax ? How many has 

 the abdomen .'' 



IV. — Returning now to the head, study the long, jointed 

 antennae. Compare the segments of these with the seg- 

 ments of the legs. Is there a similarity ? Notice the ag- 

 gregation of simple eyes near the base of each antenna. 



Unless the specimens are quite large, the mouth parts 

 are not easily distinguished by beginners. The jaws, 

 maxillae, and upper and lower lips come close together in 

 a point. The tips of the jaws are black. 



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