LIST OF ILLUSTRATIONS

PORTRAIT OF AUTHOR MAP SHOWING THE 1000-FATHOM LINE 1. DIAGRAM OF VARIATIONS OF LACERTA MURALIS 2. " VARIATION OF LIZARDS 3. " VARIATION OF WINGS AND TAIL OF BIRDS 4. " VARIATION OF DOLICHONYX ORYZIVORUS 5. " VARIATION OF AGELAEUS PHOENICEUS 6. " VARIATION OF CARDINALIS VIRGINIANUS 7. " VARIATION OF TARSUS AND TOES 8. " VARIATION OF BIRDS IN LEYDEN MUSEUM 9. " VARIATION OF ICTERUS BALTIMORE 10. " VARIATION OF AGELAEUS PHOENICEUS 11. " CURVES OF VARIATION 12. " VARIATION OF CARDINALIS VIRGINIANUS 13. " VARIATION OF SCIURUS CAROLINENSIS 14. " VARIATION OF SKULLS OF WOLF 15. " VARIATION OF SKULLS OF URSUS LABIATUS 16. " VARIATION OF SKULLS OF SUS CRISTATUS 17. PRIMULA VERIS (Cowslip). From Darwin's _Forms of Flowers_ 18. GAZELLA SOEMMERRINGI (to show recognition marks) 19. RECOGNITION MARKS OF AFRICAN PLOVERS (from Seebohm's _Charadriadae_) 20. RECOGNITION OF OEDICNEMUS VERMICULATUS AND OE. SENEGALENSIS (from Seebohm's _Charadriadae_) 21. RECOGNITION OF CURSORIUS CHALCOPTERUS AND C. GALLICUS (from Seebohm's _Charadriadae_) 22. RECOGNITION OF SCOLOPAX MEGALA AND S. STENURA (from Seebohm's _Charadriadae_) 23. METHONA PSIDII AND LEPTALIS ORISE 24. OPTHALMIS LINCEA AND ARTAXA SIMULANS (from the Official _Narrative of the Voyage of the Challenger_) 25. WINGS OF ITUNA ILIONE AND THYRIDIA MEGISTO (from _Proceedings of the Entomological Society_) 26. MYGNIMIA AVICULUS AND COLOBORHOMBUS FASCIATIPENNIS 27. MIMICKING INSECTS FROM THE PHILIPPINES (from Semper's _Animal Life_) 28. MALVA SYLVESTRIS AND M. ROTUNDIFOLIA (from Lubbock's _British Wild Flowers in Relation to Insects_) 29. LYTHRUM SALICARIA, THREE FORMS OF (from Lubbock's _British Wild Flowers in Relation to Insects_) 30. ORCHIS PYRAMIDALIS (from Darwin's _Fertilisation of Orchids_) 31. HUMMING-BIRD FERTILISING MARCGRAVIA NEPENTHOIDES 32. DIAGRAM OF MEAN HEIGHT OF LAND AND DEPTH OF OCEANS 33. GEOLOGICAL DEVELOPMENT OF THE HORSE TRIBE (from Huxley's _American Addresses_) 34. DIAGRAM ILLUSTRATING THE GEOLOGICAL DISTRIBUTION OF PLANTS (from Ward's _Sketch of Palaeobotany_) 35. TRANSFORMATION OF ARTEMIA SALINA TO A. MILHAUSENII (from Semper's _Animal Life_) 36. BRANCHIPUS STAGNALIS AND ARTEMIA SALINA (from Semper's _Animal Life_) 37. CHIMPANZEE (TROGLODYTES NIGER)