Contents: Introduction. 1. Phylum arthropoda. 2. Subphylum Chelicerata. 3. Class Arachnida. 4. Subclass Merostomata. 5. Order Xiphosura. 6. Family Limulidae. 7. Order Scorpionida. 8. Family Buthidae. 9. Family Chaerilidae. 10. Family Vaejovidae. 11. Family Scorpionidae. 12. Order Acari (=Acarina). 13. Suborder Metastigmata. 14. Family Argasidae. 15. Family Ixodidae. 16. Suborder Astigmata. 17. Family Pyroglyphidae. 18. Suborder Prostigmata. 19. Family Ascidae. 20. Family Eriophyidae. 21. Family Tetranychidae. 22. Family Tarsonemidae. 23. Family Tenuipalpidae. 24. Family Lardoglyphidae. 25. Family Cheyletidae. 26. Family Otopheidomenidae. 27. Family Rhyncaphytoptidae. 28. Suborder Mesostigmata. 29. Family Demodicidae. 30. Family Dermanyssidae. 31. Family Knemidokoptidae. 32. Family Psoroptidae. 33. Family Phytoseiidae. 34. Family Sarcoptidae. 35. Suborder Oribatida. 36. Family Phiracaridae. 37. Family Euphthiracaridae. 38. Family Tectocepheidae. 39. Order Araneae. 40. Suborder Labidognatha. 41. Family Araneidae. 42. Family Clubionidae. 43. Family Gnaphosidae. 44. Family Hersiliidae. 45. Family Linyphiidae. 46. Family Lycosidae. 47. Family Oonopidae Simon. 48. Family Oxyopidae. 49. Family Philodromidae O.P. Cambridge. 50. Family Pholcidae. 51. Family Pisauridae. 52. Family Salticidae. 53. Family Sparassidae. 54. Family Tetragnathidae. 55. Family Theridiidae. 56. Family Thomisidae. 57. Family Uloboridae. Glossary. References. Index of scientific names. Index of English and local names.