LABORATORY EXERCISES 121 



Compare pleopods of male and female. Study with a lens a 

 pleopod of segment 1 6 or 17; there is a basal protopod, a lateral 

 exopod and a medial endopod. 



(d) Study the region of the mouth in a ventral view, to show espe- 

 cially the appendages 3-8 (see c above). Begin with appendage 

 8 and work forward. 



(e) In a ventral view of the entire animal note the openings of the 

 green glands on the basal segments of the antennae, the openings 

 of the gonoducts at the base of the eleventh (female) or thirteenth 

 (male) appendages, and the anal opening. Draw the appendages 

 9-13 in detail, showing all the joints. 



(f) Note the sensory hairs. Where are they found? In the eyes 

 note the eye stalk and the retina. Study a preparation of the 

 retina with the microscope. With the point of a needle search 

 the dorsal surface of the basal segment of the antennule for the 

 opening into the statocyst. 



(g) In a specimen in which the gill chamber has been laid open 

 note character of the gills, their number, position and mode of 

 attachment to the body. With a lens study a single gill under 

 water in a watch glass. 



(h) In a specimen that has been sectioned longitudinally near the 

 median plane note: (i) the digestive tract with oesophagus, 

 cardiac and pyloric portions of the stomach, the liver and the 

 intestine; (2) the heart in the pericardial chamber under the 

 posterior edge of the thoracic shield and the arteries (ophthal- 

 mic, sternal and abdominal), (3) the gonads lying below the 

 heart, (4) the green gland above the basal joint of the antenna, 

 (5) the large complicated muscles of the abdomen, (6) the ventral 

 nerve cord communicating with the brain. 



(i) In a side view of a grasshopper (Schistocerca) show in the body: 

 head, prothorax, mesothorax, metathorax, abdomen. The 

 appendages are; antennas, lab rum, maxillae, with maxillary palps, 

 labium with labial palps, legs. The parts of a leg are; coxa, 

 femur, tibia and tarsus. 



(j) Remove the wings and draw the thorax and abdomen on a larger 

 scale. Note especially the tympanum and the ten spiracles 

 eight on the abdomen and two on the thorax. Note the number 

 of segments in the abdomen and compare male and female. 



(k) Draw both wings of one side expanded. 



