EPHEMERIDA 65 



8. Keep the others in an aquarium with water weed and 

 exclude all carnivorous animals. 



9. Pin and mount a few specimens on a spreading board. 



10. Prepare slide mounts of the wings of the adult. 



11. Prepare slide mounts of the legs and tails of the adult. 



12. Prepare slide mounts of mouthparts of any of the 

 nymphs. 



13. Routine (see p. 204). 



LA BORA TOR Y PROGRA M 



A. The Study of Living Specimens. 



Adult mayflies must be studied in the field, where, only, 

 they behave normally; but the living nymphs are quite 

 available for study in the laboratory. In all of them first 

 note the presence of paired more or less leaflike gills on the 

 back of the abdominal segments — this is the best distinctive 

 mark of a mayfly nymph. Then note: 



1. The shuttle-like shifting of the gills for contact with 

 fresh water and better aeration. 



2. The use of the legs in climbing and clinging. 



3. Their rather indifferent swimming by undulations of 

 the body and backward lashings of gills and tail. 



4. Throw a burrowing nymph out of the sand and watch 

 it dig in again. Observe how it lifts with its tusks, 

 scrapes the sand aside with its front feet and pushes 

 with its hind feet. 



