1911] May-Flies of Fall Creek, N. Y. 119 



EXPLANATION OF PLATES. (All figures much enlarged.) 

 PLATE VI. 

 Heads of Ephemerella nymphs. 

 Fig. 1. Ephemerella rotunda sp. nov. 

 " 2. " tuberculata " 



" 3. " cornuta " 



" 4. " deficiens 



" 5. " serrata " 



" 6. " lata 



PLATE VII. 

 Legs of Ephemerella Nymphs. 

 Fig. 1. Right legs of Ephemerella lata sp. nov. 



" 2. " foreleg " " serrata " 



" 3. " " " " rotunda 



" 4. " " " " deficiens " 



" 5. " " " " tuberculata " 



" 6. " " " " cornuta 



These drawings are all made from the upper or dorsal aspect. The enlarged 

 sketches of the claw and tarsus of each show the ventral aspect of the tarsus with 

 its chitinous comb which is used in clinging to the rocks. 



PLATE VIII. 

 Mouth-parts of Ephemerella nymphs. 

 Fig. 1. Mouth-parts of Ephemerella lata. sp. nov.; r. md., right mandible; 

 1. md., left mandible; lr., labrum; 1., labium; mx., left maxilla; hy., hypopharynx, 

 viewed from above. 



Fig. 2. Left maxilla of Ephemerella serrata sp. nov. 

 " 3. " " " " tuberculata " 



" 4. " " " " deficiens 



" 5. " " " " rotunda 



" 6. " " " " cornuta " 



PLATE IX. 

 Epeorus and Ephemerella. 



Fig. 1. Epeorus humeralis sp. nov. Portions of the 3rd and 4th abdominal 

 segments of the nymph with gills removed, to show lateral spines. 



Fig. 2. Forceps and penes of Epeorus humeralis, sp. nov. (From below.) 

 " 3. " " " " Ephemerella serrata sp. nov. (From below) 



" 4. " " " " " deficiens " (From below). 



" 5. Wings of " cornuta " 



" y " " rotunda 



" 7. " Epeorus humeralis " 



PLATE X. 

 Iron fragilis sp. nov. 

 Fig. 1. Mouth-parts of the nymph; 1, outer aspect of the labium; 11., inner 

 aspect of the labium; r. md., right mandible; 1. md., left mandible; hy., hypopharynx. 

 Fig. 2. Wings. 



Fig. 3. Foreleg of the male imago. 



Fig. 4. Forceps and penes from below; dotted lines represent the portion of 

 the penes hidden by the last sternite. 



PLATE XI. 

 Tricorythus allectus Needham. 

 Fig. la. Elytroid lamella; hy., hypopharynx; 



" lr. labrum; r. md., right mandible; 1. md., left mandible. 

 " mx. left maxilla; 1., labium. 



. PLATE XII. 

 Fig. 1. Surface of stone covered with masses of Baetis eggs. 

 " 2. A few of the masses enlarged. 



