20 a Canadian Arctic Expedition, 1913-18 



EXPLANATION OF PLATES. 

 All the figures except Nos. 19, 20, G7, 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 mucro, 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. 



Plate 2. 



Fig. 11. Achorutes tullbergi, right anal spine, X 577. 



12. Achorutes sensilis, postantennal organ and two eyes of left side, X 577. 



13. Achorutes sensilis, 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 seta? of second abdominal segment, X 297. 



19. Achorutes viaticus, sense organ of third antennal segment of right side, from a European 



specimen, X 90S. 



20. Achorutes viaticus, dorsal setae of second abdominal segment, from a European speci- 



men, X 337. 



Plate 3. 



Fig. 21. Achorutes armatus, left postantennal organ, X 505. 



22. Achorutes anna/us, right fore foot, X 300. 



23. Achorutes armatus, left mucro, X 505. 



24. Achorutes armatus, left anal spine, X 505. 



25. Achorutes armatus, dorsal seta? 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, s'ense organ of third antennal segment of left side, X 800. 



29. Onychiurus duodecimpunctatus, dorso-lateral aspect, to show pseudocelli, X 35. 



30. Onychiurus duodecimpunctatus, left hind foot, X 505. 



Plate 4. 



Fig. 31. Onychiurus duodecimpunctatus, right anal spine, X 635. 



32. Onychiurus duodecimpunctatus, dorsal setse of second abdominal segment, X 295. 



33. Tetracanthella wahlgreni, X 42. 



34. Tetracanthella wahlgreni, eyes and postantennal organ of right side, X 252. 



35. Tetracanthella wahlgreni, sense organ of third antennal segment of left side, X 825. 



36. Tetracanthella wahlgreni, extremity of abdomen, .X 185. 



37. Tetracanthella wahlgreni, dorsal aspect of anal spines, X 250. 



Plate 5. 



Fig. 38. Tetracanthella wahlgreni, left hind foot, X 505. 



• 39. Tetracanthella wahlgreni, furcula and tenaculum, X 505. 



40. Tetracanthella wahlgreni, dorsal aspect of muerodentes. X 505. 



41. Tetracanthella wahlgreni, dorsal setse of first abdominal segment, X 295. 



42. Folsomia quadrioculata, eyes and postantennal organ of left sfde, X 505. 



t:;. Folsomia quadrioculata, sense organ of third antennal segment of right side, X 825. 



44. Folsomia quadrioculata, right hind foot, X 505. 



15. Folsomia quadrioculata, portion of furcula, X 505. 



40. Folsomia quadrioculata, left aspect of furcula, X 295. 



47. Folsomia quadrioculata, dorsal setse of second abdominal segment, X 295. 



