14 INVERTEBRATE ZOOLOGY 



Exercise 11. Remove carefully and with the aid of the dissecting 

 microscope, if necessary, the antennae, labrum, mandibles, 

 maxillae, and labium of the beetle. Mount them on a 

 slide and draw them on a large scale. Label carefully 

 all the parts. 



Exercise 12. The mouth-parts of the wasp are much more 

 highly specialized than those of the beetle, as they are 

 adapted not only for chewing, but also for licking. Remove 

 the antennae and the mouth-parts of the wasp and mount 

 them on a slide. The labrum and the mandibles will be 

 seen to be similar to those already studied. The maxillae 

 and the labium, also, do not differ materially from those of 

 the beetle or the grasshopper. The labium lies between 

 the two maxillae, and its ligula is elongated and modified 

 to form a licking organ. Draw an antenna and the mouth- 

 parts on a scale of 6. 



Internal anatomy. Take the grasshopper in the hand and with 

 a pair of fine, sharp scissors cut a slit through the body-wall a 

 little to one side of the mid-dorsal line from one end of the 

 body to the other, using great care not to injure the organs 

 within. Place the animal, dorsal side up, in a shallow pan 

 with a wax -covered bottom containing water or 30J& alcohol. 

 First, with two strong pins, pin the head to the wax and then 

 the extreme hinder end of the body, then carefully spread the 

 cut edges of the body-wall as widely as possible to the right 

 and left and pin them down, using many pins on each side. 

 Observe the organs as they lie in the body-cavity. In the 

 thorax will be seen the strong locomotory muscles. Lying 

 immediately beneath the dorsal abdominal wall in the median 

 line is the heart ; this may have been destroyed by the incision, 

 but if not, it may be recognized as a narrow, transparent tube 

 of the diameter of a needle, flanked by paired triangular muscles 



