EEV. A. E. EATON ON EECENT EPIIEMERID.E OR MAYFLIES. 343 



Plate LIII. 



Last slough cast by the nymph of a nameless insect, described at pp. 229-230. 



Figs. 1-14, all enlarged. — 1. Dorsal view of slough, defective in flie sette and in the five hinder pairs 

 of abdominal tracheal branehiiB. 2. Antenna, x 35 diam. 3. Exterior of labrum [attached 

 to the frons, with antennae partly removed], x 10 diam. 4 & 5. Left mandible in two 

 jDOsitions, x 20 diam. G. First maxilla and palpus, with a portion of the tongue (paraglossa) 

 adhering, x 12 diam. 7. The same palpus, x 65 diam. 8. Underside of labium, 2ud 

 maxillae, palpi, &c., x 12 diam. 9. One of the same palpi, x 25 diam. 10-12. Legs 

 numbered successively from the foremost, x 10 diam. 13. One of the tracheal branchiae of 

 the foremost abdominal pair, x 12 diam. 14. Right tracheal branchia of the 2nd abdominal 

 pair, in reverse, x 12 diam. (Slough dried; scalded.) 



Plate LIV. 



Rhith'ogena aurantiaca and [figs. 3 & 4] Rh. semicolorata. Nymphs. 



Figs. 1-24, all enlarged. — 1 Dorsal view of insect of very advanced grade, in repose, with tracheal 

 branchiae spread. 2. Ventral view of head and body of the same. 3. Dorsal view of another, 

 with the laminae of the tracheal branchiae deflected. 4. Side view of the same. 5. F'ace, 

 upside down, with antennae partly removed, x 12 diam. 6. Antenna, x 35 diam. 7. Labrum, 

 x 35 diam. 8. Right mandible, x 60 diam. 9. Left ditto, x 60 diam. [Point of mandible 

 more enlarged, PI. LXV. 6.] 10. First maxilla and palpus, x 35 diam. 11. Underside of 

 labium, 2ud maxillae, and palpi, x 35 diam. 12. Ditto, reversed. 13. Dorsal view of tongue 

 and paraglossae, x 35 diam. 14-16. Left legs, numbered successively from the foremost, x 

 15 diam. 17-23. Tracheal branchiae of the abdomen, one of every i^air, numbered consecutively 

 from the foremost, x 25 diam. 24. Left and median caudal setae, x 15 diam. [Rh. auran- 

 tiaca, in fluid, from Tarascon, Ariege ; Rh. semicolorata, in alcohol, from Dorset.) 



Plate LV. 



Iron, sp. Nymph. 



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

 and l)ody of the same. 3. Face with antennae partly removed. 4. Antenna, x 30 diam. 

 5. Exterior of labrum, x 80 diam. 6. Right mandible, x 50 diam. 7. Left ditto. 8. First 

 maxilla and palpus, x 65 diam. 9. Underside or exterior of labium, 2nd maxilhe, and palpi, 

 x 30 diam. 10-12. Right legs [with the hairs of the tibiie accidentally thrown backwards, 

 and those of the tarsi out of sight] numbered successively from iu front, x 15 diam. 13- 

 19. Tracheal branchia; of the abdomen, one of eveiy pair, numbered consecutively from the 

 foremost, x 30 diam. [In alcohol, from Dr. Hagen.] 



Plate LVI. 



Epeorus torrentium. Nymph. 

 Figs. 1-22, all enlarged. — 1. Dorsal view of J insect of very advanced grade, in repose. 2. Ventral 

 view of head and body of the same. 3. Face, x 9 diam. 4. Antenna, x 30 diam. 

 5. Exterior of labrum, x 30 diam. 6. Right mandible, x 50 diam. 7. Left, ditto. 8. First 

 maxilla and palpus, x 30 diam. 9. Underside or exterior of labium, 2nd maxillae, and palpi, 

 X 25 diam. 10. Upperside or interior of ditto. 11. Tongue and paraglossae, x 30 diam. 

 12-14. Left legs, numbered successively from the foremost, x 10 diam. 15-21. Tracheal 

 branchiae of the abdomen, one of every pair, numbered consecutively fi-om in front, x 20 diam. 

 22. One caudal seta and part of the other, x 12 diam. [In alcohol, from Tarascon, Ariege.] 

 SECOND SERIES. — ZOOLOGY, VOL. III. 46 



