20 A Canadian Arctic Expedition, 1913-18 
EXPLANATION OF PLATES. 
All the figures except Nos. 19, 20, 67, 70 and 71 are from specimens collected by the Expedition. 
Plate 1. 
Fig. 1. Podura aquatica, right hand foot, X 337. 
2. Podura aquatica, dorsal aspect of left macro, X 577. 
3. Podura aquatica, left mucro, X 577. 
4. Achorutes tullbergi, eyes of left side, X 577. 
5. Achorutes tullbergi, sense organ of third antennal segment of right side, X 908. 
6. Achorutes tullbergi, right mid foot, X 577. 
7. Achorutes tullbergi, left mucro, X 577. 
8. Achorutes tullbergi, right mucro, X 577. 
9. Achorutes tullbergi, left mucro, X 577. 
10. Achorutes tullbergi, anal spines, X 908. 
Pl.\te 2. 
Fig. 11. Achorutes tullbergi, right anal spine, X 577. 
12. Achorutes sensilis, postantennal organ and two eyes of left side, X 577. 
13. Achqrutes seyisilis, sense organs of third antennal segment of left side, X 577. 
14. Achorutes sensilis, left hind foot, X 341. 
15. Achorutes sensilis, right mucro, X 577. 
16. Achorutes sensilis, left mucro, X 577. 
17. Achorutes sensilis, left anal spine, X 560. 
18. Achorutes sensilis, dorsal setae of second abdominal segment, X 297. 
19. Achorutes viaticus, sense organ of third antennal segment of right side, from a European 
specimen, X 908. 
20. Achorutes viaticus, dorsal setae of second abdominal segment, from a European speci- 
men, X 337. 
Plate 3. 
Fig. 21. Achorutes armatus, left postantennal orgaji, X 505. 
22. Achorutes armatus, right fore foot, X 300. 
23. Achorutes armatus, left mucro, X 505. 
24. Achorutes armatus, left anal spine, X 505. 
25. Achorutes armatus, dorsal setaj of first abdominal segment, X 295. 
26. Onychiurus duodecimpunctatus, right postantennal organ, X 505. 
27. Onychiurus duodecimpunctatus, pseudocelli of right antennal base, X 295. 
28. Onychiurus duodecimpunctatus, sense organ of third antennal segment of left side, X 800. 
29. Onychiurus duodecimpunctatus, dorso-lateral asi)ect, to show pseudocelli, X 35. 
30. Onychiurus duodecimpunctatus, left hind foot, X 505. 
Plate 4. 
Fig. 31. OnyrJiiurus duodecimpunctatus, right anal spine, X 635. 
32. Oiiyrhinn(>i (hiodccimpunctatus, dorsal setae of second abdominal segment, X 295. 
33. TiirdcdiilhilUi u-ahlgreni, X 42. 
34. TetnicutilhiUd iruhlgreni, eyes and postantennal organ of right side, X 252. 
35. TetrucantlicUd irahlyreni, sense organ of third antennal segment of left side, X 825. 
36. Tetracanlhella wahlgreni, extremity of abdomen, X 185: 
37. TetracantheUa wahlgreni, dorsal aspect of anal spines, X 250. 
Plate 5. 
Fig. 38. TetracantheUa wahlgreni, left hind foot, X 505. 
39. TetracantheUa wahlgreni, furcula and tenacuhim, X 505. 
40. Tetracanthella wahlgreni, dorsal aspect of mucrodentes, X 505. 
41. Tetracanthella unhlgreni, dorsal seta^ of first abdominal segment, X 295. 
42. Folsonria guailrioi'ulata, eyes and i)()stant(>nnal organ of left side, X 505. 
43. Folsomia quadrioculata, sense organ of third antennal segment of right side, X 825. 
44. Folsomia quadrioculata, right hind foot, X 505. 
45. Folsomia quadrioculata, portion of furcula, X 505. 
46. Folsomia quadrioculata, left aspect of fiu'cula, X 295. 
47. Folsomia quadrioculata, dorsal setae of second abdominal segment, X 295. 
