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APPLIED BIOLOGY 



How many appendages on each segment ? Do any segments lack 

 appendages ? In what direction can the abdomen be bent ? Can it 

 bend laterally? Compare with joints of appendages. Bend the 

 abdomen and make sketch showing the second, third, and fourth 

 segments seen in side view. Now straighten the abdomen and 

 sketch the same segments. Notice the white membrane which unites 

 the segments. 



.cephalo-thorax abdomen 



mall antenna 



large antenna 



FIG. 116. Crayfish with side of carapace removed to expose the gills, e, 

 eye ; c, base of great claw ; /, scoop which drives water out of gill-chamber ; 

 6, bases of four walking legs ; a, swimmerets. (From Morse.) 



Cephalothorax. The sides and dorsal surface are in this region 

 covered by a hard shield known as the carapace. Notice the groove 

 which marks the line between the head and thorax. On the head 

 portion notice the beak; the eyes ; the mouth on the ventral side 

 (may be seen by separating the appendages). 



Make outline drawing of the animal as seen in dorsal or lateral 

 view. (Also ventral view, if time permits.) 



Appendages of the Abdomen. What segments (use numbers) of 

 the abdomen bear appendages ? Beginning at the posterior end of 

 the body, carefully use the fine pointed forceps in removing the 

 appendages of one side in order, or examine a mounted set of the 



