EPHEMERIDA 67 



II. In the thorax. 



1. The great size of the meso thorax; it contains the 

 muscles that move the large fore wings. Note its form 

 and finish. 



2. The excessive length of the fore legs, especially in the 

 male. 



3. The five segments of the tarsus, consolidated basally 

 with the tibiae in middle and hind legs. 



4. The form of the tarsal claws. Are those on each tarsus 

 alike in form? 



5. The small size of the hind wing and the lengthwise 

 furrowing and dense venation of both wings. 



III. In the abdomen, note. 



1. The ten free segments. 



2. The two or three long tails. 



3. In the males, a pair of jointed forceps beneath the 

 terminal segments. 



b. Nymphs 

 In any of the three types observe: 



1. The biting mouthparts. 



2. The slender antennae. 



3. The large compound eyes. 



4. The one-jointed tarsi, each with a single claw. 



5. The wing cases right side up (not inverted, as in dragon- 

 fly nymphs). 



