EEV. A. E. EATOX OX EECEXT EPHEMEEID^ OE MAYFLIES. 341 



Plate XLVI. 



CentroptUum luteolum. Nymph. 

 Figs. 1-19, all enlarged. — 1. Dorsal view o£ insect of advanced grade, in repose. 2. Ventral view of 

 head and body of the same. 3. Antenna, x 25 diam. 4. Exterior of labrum, x 65 diam. 

 5. Eight mandible with tendon attached, x 100 diam. 6. Left ditto. 7. First maxiUa 

 and palpus, x 100 diam. [The palpus is only 3-jointed. The artist has mistaken the prop 

 upon which the palpus is inserted for a 4th joint, and focussed the underlying edge of the 

 stipes. Compare the corresponding figures in Pis. XLVII. & L.] 8. Underside of labium, 

 2nd maxillae, and palpi, x 65 diam. 9. Dorsal view of tongue and paraglossas, x 65 diam. 

 10-12. Legs numbered consecutively from the foremost, x 30 diam. 13-19. Tracheal 

 branchiae of the abdomen, one of every pair, numbered consecutively from the foremost, x 60 

 diam. (In fluid.) 



Plate XLVII. 



Clo'eon riifulum, figs. 1 & 4, c. simile, figs. 2, 3, 5-21, and c. dipterum, fig. 22. Nymphs. Figures all 

 enlarged. — 1. Dorsal view of? insect of advanced grade, in repose [the legs not in perspective]. 



2. Side v-iew of prothorax and head, with the fore leg and antenna cut off, x 25 diam. 



3. Front view of head, x 25 diam. 4. Antenna, x 18 diam. [The antennae of the other 

 species are much shorter and have fewer joints.] 5. Exterior of labrum, x 35 diam. 6. Right 

 mandible, x 70 diam. 7. Left ditto with part of the stipes omitted. 8. Lacinia and palpus 

 of the right 1st maxilla, x 70 diam. 9. Left 1st maxilla and palpus, x 70 diam. 10. Under- 

 side view of labium, 2nd maxillae, and palpi, x 35 diam. 11. Dorsal view of tongue and 

 paraglossfe, x 35 diam. 12-14. Legs numbered successively from the foremost, x 18 diam. 

 15-21. Right tracheal branchiae of the abdomen reversed, one of every pair, x 25 diam. 

 22. Right and median caudal seta^ x 10 diam. [The tail-points of most of the species are 

 short like these.] (In fluid.) 



Plate XLVIII. 



Callibtetis, sp. Nymph. 

 Figs. 1-19, all enlarged. — 1. Dorsal view of ? insect of very advanced grade. 2. Ventral view of 

 head and body of the same. 3. Antenna, x 23 diam. 4. Exterior of labrum, x 45 diam. 

 5. Right mandible with tendon attached, x 65 diam. 6. Left mandible, x 65 diam. 7. First 

 maxilla and palpus, x 65 diam. 8. Underside of labium, 2nd maxillae, and palpi, x 35 diam. 

 9. Dorsal view of tongue and paraglossae [enlargement unrecorded] . 10-12. Legs numbered 

 successively from the foremost, x 20 diam. 13-19. Right tracheal branchiae (in reverse) of 

 the abdomen, one of every pair, numbered consecutively from the foremost, x 30 diam. (In 

 alcohol, from Dr. Hagen.) 



Plate XLIX. 



? Chirotonetes, sp. Nymph. 

 Figs. 1-19, all enlarged. — 1. Dorsal view of insect of very advanced grade, in a conventional posture. 

 2. Ventral dew of head and body of the same. 3. Antenna, x 30 diam. 4. Labrum, x 30 

 diam. 5. Right mandible, with tendon attaclied and muscular tissue within the hollow of the 

 stipes, X 50 diam. 6. Left ditto. 7. First maxilla and palpus, x 50 diam. 8. Underside 

 of labium, 2nd maxillae, and palpi, x 50 diam. 9. Dorsal view of tongue and parao-lossie 

 X 30 diam. 10-12. Legs numbered successively from the foremost, x 15 diam. 13-19. 

 Right tracheal branchiic (in reverse) of the abdomen, one of every pair, x 50 diam. (lu 

 alcohol, from Dr. Hagen.) 



