THE CRAYFISH 93 



(2) Study the ventral view of the head. What mouth 

 parts are there ? Are the mandibles segmented ? Where are 

 the mandibles located with reference to the other mouth 

 parts? Are they similarly located in insects? What do 

 these facts teach with reference to the mandibles? Do you 

 find indications of mandibles under the labrum? 



The Body. — How many segments? How are they joined 

 together ? How many feet ? Count the segments. How do 

 they end? Look between dorsal and ventral sides for spir- 

 acles. How many? Compare this animal with the larva 

 of butterfly? Of beetle? 



Make drawing of dorsal side (X2). Also ventral side 



(X2). 



Development.^ — The centipede belongs to the class My- 

 riapoda and is one of the most timid of the class. Its eggs 

 are hatched into a form similar to the adult, and the animal 

 grows by molting and adding segments back of the head. 



Habits. — Where is this animal found? What does it 

 do when discovered ? Do all " thousand legs " act in the 

 same way ? From its mouth parts what do you think is the 

 nature of its food? How does the centipede defend itself? 

 Do you think it is poisonous ? Do you believe the stories 

 told about the deadly effects of the centipedes of Texas? 

 Why not? 



THE CRAYFISH 



Camharus sp. 



General Directions. — Crayfish may be found in ponds 

 and streams at any time of the year, except in winter. They 

 may be kept for a short time in a vessel with a small amount 



