6 PRACTICAL ZOOLOGY. 



laying the egg these points are first pressed together, 

 then thrust into the ground, and then separated ; this 

 process is repeated till a hole is made, sometimes as 

 deep as the abdomen is long, at the bottom of which the 

 eggs are deposited, passing out between the four points 

 of these egg guides, which together are called the 

 ovipositor; compare the inner and outer surfaces of 

 these egg guides. The males are smaller than the 

 females. Draw the abdomens, as seen from the side, 

 of both the male and the female. Take now an entire 

 specimen and draw a side view of it. 



INTERNAL STRUCTURE OF THE GRASSHOPPER. 



This work would better be done after the student has 

 dissected the crayfish. Dissect under water with the dis- 

 secting pan as described under the " crayfish." 



1. Get a large female grasshopper, freshly killed. Cut 

 off the wings, and place the specimen, back upper- 

 most, in the dissecting pan ; pin the hindermost ring 

 of the abdomen firmly to the bottom of the dissecting 

 pan ; turn each hind leg outward and pin down. 

 With sharp, fine-pointed scissors, cut through each 

 side of the roof of the next to the last abdominal ring; 

 lift, with the forceps, the cover of this ring ; continue 

 the cut forward, on each side of the abdomen, pulling 

 the tergum upward and forward as it is loosened. 

 Thus carefully unroof the whole abdomen. 



2. The heart is a delicate tube, running along just 

 under the tergum, and probably was torn away with 

 the tergum. 



8. On each side there should now be seen a row of air 

 sacs, with their white air tubes. 



