MOUTH PARTS OF THE NYMPH. 



II. Mandible Without Tusk — Continued. 



(cc) Outer edge of mandible with a gentle 

 curve midway between base and 

 apex, and with short spines, tf. 20. 

 (aaa) Outer canine with three large teeth, 

 (b) Inner canine with 4 teeth, tf. 15. 

 (bb) Inner canine with 3 teeth, 

 (bbb) Inner canine with 2 teeth. 



(c) Outer edge of mandible serrated ; 

 lacinia broad at base, and cone- 

 shaped, tf. 1. 

 (cc) Outer edge of mandible not serrated ; 

 lacinia slender, tf . 2. 

 AA. Outer canine without large teeth, more or less scoop- 

 shaped ; edge crenated. HEPT. 

 (a) Outer canine with small teeth at apex. 



(b) Outer canine, with 1 small tooth at apex, 



tf. 5. 

 (bb) Outer canine with 2 small teeth at apex, 

 tf. 6. 

 (aa) Outer canine without small teeth at apex ; edge 

 finely crenated. 

 (b) Inner canine not more than y 2 length of 

 outer canine (PI. IV, fig. 48). 

 (bb) Inner canine more than l /> length of outer 

 canine. 



(c) Inner canine but little over J/> length 

 of outer canine; edge coarsely 

 crenated, tf. 4; outer canine 

 sharp at tip, tf. 7. 

 (cc) Inner canine almost as long as outer 

 canine, tf. 16; edge finely 

 crenated ; outer canine blunt at 

 apex, tf. 11. 



Ephemerella. 



Chirotenetes. 

 Choroterpes. 



Baetisca. 

 Lcptophlebia. 

 4GENINAE. 



Hcptagenia. 

 Ecdyuruj. 



Rhithrogena. 



Epeorus. 



Iron. 



15 



