338 EEV. A. E. EATON ON EECENT EPHEMEEID^E OE MAYFLIES. 



maxilla and palpus, x 65 diam. 8. Part of the laciuia of the same maxilla reversed, x 65 

 diam. 9. One of the pectinate spinules at the extreme point of the same, more enlarged. 

 10. Underside of hypopharynx, labium, 2nd maxillae, and palpi, x 65 diam. 11. Part of the 

 same reversed, x 65 diam. 12. Dorsal view of tongue and paraglossse [no record of 

 enlargement]. 13-15. Fore, intermediate, and hind legs numbered consecutively, X 20 diam. 

 16-22. Tracheal branchise of the abdomen (the right one of every pair) numbered consecutively 

 from the foremost, all x 20 diam. 23. The foremost of the same, x 35 diam. 24. The 

 outer and median caudal setae, x 20 diam. (In fluid.) 



Plate XXXVII. 



Ephemerdla igmta. Nymph. 



Figs. 1-20, all enlarged. — 1. Dorsal view of $ insect, with legs in a conventional posture ; a light- 

 coloured specimen captured in the Holybrook above Reading, Berks, similar to that figured by 

 Pictet, op. cit. pi. xxix. 1, and of very advanced grade. 2. Ventral view of a dark ^ specimen 

 captured in a trout-stream, similar to that figured by Pictet, op. cit. pi. xxxiii. 1, and of very 

 advanced grade. 3. Head of <S , from in front. 4. Antenna, x 50 diam. 5. Exterior of 

 labrum, x 50 diam. 6 and 7. Right and left mandibles, with tendon attached, x 80 diam. 

 8. First maxilla and palpus, x 80 diam. 9. Underside view of labium, 2nd maxillae, and palpi, 

 X 85 diam. 10. Dorsal view of tongue and paraglossae, x 50 diam. 11-13. Legs numbered 

 consecutively, x 40 diam. 14-18. Tracheal branchiie of the abdomen (the left one of every 

 pair) numbered consecutively from the foremost, x 45 diam. 19. The third of the same 

 reversed to display the lamclligerous appendage, x 70 diam. 20. Outer and median caudal 

 setfe of J" , X 25 diam. (In fluid.) This Plate underwent considerable revision upon the stone 

 before publication. 



Plate XXXVIII. 



Figs. ]-10. Nymph No. I., allied to Ephemerella, described at p. 131. Figures all enlarged. — 

 1. Dorsal view of insect of advanced grade, with the legs disposed conventionally. 2. Ventral 

 view of head and body of the same. 3. Front view of head, x 12 diam. 4. First maxilla and 

 palpus, X 70 diam. 5. The same reversed. 6-8. Legs of the left side numbered in succession, 

 X 15 diam. 9. Spinules of the lower edge of the fore femur, x 60 diam. 10. A hair from 

 the upper edge of the hind femur, x 95 diam. (In alcohol.) 



Figs. 11-15. Nymph No. II. (p. 131). Figures all enlarged. — 11. Dorsal view of insect of advanced 

 grade, in repose. 12. Ventral view of head and body of the same. 13. Side view of the 

 same. 14. Front view of head. 15. First maxilla and palpus, x 40 diam. (In alcohol.) 



Plate XXXIX. 



Nymph No. III., allied to Ephemerella, described at p. 132. 

 Figs. 1-22, all enlarged. — 1. Dorsal view of insect of very advanced grade. 2. Dorsal view of the 

 headless body of a younger specimen, with the tracheal branchiae removed from the right side 

 of the abdomen and depressed on the left side of the same. 3. Ventral view of head and 

 body of the same. 4. Front view of head, x 12 diam. 5. Antenna, x 30 diam. 6. Exterior 

 of labrum, x 40 diam. 7. Right mandible, x 65 diam. 8. Left mandible, with part of 

 the stipes omitted, x 65 diam. 9. Molar surface of the same, x 170 diam. 10. First 

 maxilla and palpus, x 65 diam. 11. Underside of labium, 2nd maxilla;, and jjalpi, x 40 diam. 



