AKTHKOPODA. 55 



Why are the antennse so small in the shrimp and 

 so large in the crayfish ? (Remember that the 

 shrimp and the crayfish swim in opposite direc- 

 tions.) 

 h. Identify the prominent stalked eyes. 



c. Identify also a single smaller median eye. 



d. Where is the mouth located ? 



e. Identify a large pair of jaw-like organs. (These 



are modified antennse and are present only on 

 the male shrimp.) 



2. Of the Thorax : — 



a. Identify the prominent gills. 



h. How many pairs of gills are there ? 



c. What two uses have these gills ? 



3. Of the Abdomen : — 



a. Are any swimmerets present ? 



b. What is peculiar to the appendages of the last 



somite? (1.) What is the probable use of 

 these appendages ? 



c. Notice the packet of eggs attached to the female 



shrimp. 



d. Is the packet of eggs situated dorsally or ven- 



trally ? 



e. Is the packet of eggs carried above or below the 



shrimp when it swims '? 

 Why does not the shrimp have a caudal fin ? 



I). Make Sketches to illustrate this study. 



5. THE LOCUST. " Grasshopper." 

 A. Habitat. 



1. Where do grasshoppers live ? 



2. Do they like sunny or shady fields ? 



