| FIG. | | PAGE |
| 1. | Paramecium. (From “Animal Biology.” Longmans) | 4 |
| 2. | Behaviour of Paramecia. (After Jennings, American Journal of Psychology) | 8 |
| 3. | Cell-division. (From “Animal Biology.” Longmans) | 13 |
| 4. | Wapiti with antlers in velvet. (Drawing by Mr. Charles Whymper, after photograph by Miss Reynolds) | 16 |
| 5. | Wapiti with velvet shredding off. (Drawing by Mr. Charles Whymper, after photograph by Miss Reynolds) | 17 |
| 6. | Sun-dew leaf and tentacles. (From Darwin’s “Insectivorous Plants.” Murray. By kind permission of Mr. Francis Darwin, F.R.S.) | 26 |
| 7. | Venus’s Fly-trap. (From Darwin’s “Insectivorous Plants.” Murray. By kind permission of Mr. Francis Darwin, F.R.S.) | 27 |
| 8. | Flower of Valisneria | 28 |
| 9. | Flower of Catasetum | 30 |
| 10. | Flower of Catasetum dissected. (From Darwin’s “Fertilization of Orchids.” Murray. By kind permission of Mr. Francis Darwin, F.R.S.) | 31 |
| 11. | Solitary Wasp stinging Caterpillar. (After Plate III. in Dr. and Mrs. Peckham’s “Solitary Wasps”) | 75 |
| 12. | Solitary Wasp dragging a Caterpillar to its Nest. (After Plate IV. in Dr. Peckham’s “Solitary Wasps”) | 76 |
| 13. | Insect Larvæ: Sitaris, Argyromœba, and Leucopsis. (After Fabre “Souvenirs”) | 80 |
| 14. | Yucca Flower and Moth | 83 |
| 15. | Newly-hatched Chick swimming. (Drawn by Mr. Charles Whymper, after instantaneous photographs and a sketch by the author) | 85 |
| 16. | Nestling Megapode. (From Dr. R. Bowdler Sharpe’s “Wonders of the Bird World.” Wells Gardner) | 87 |
| 17. | Cuckoo ejecting Meadow Pipit. (From Mrs. Hugh Blackburn’s sketch in “Birds from Moidart.” David Douglas) | 91 |
| 18. | Leaf-case of Birch-weevil | 121 |
| 19. | Solitary Wasp using a stone as a tool. (After Plate V. in Dr. Peckham’s “Solitary Wasps”) | 127 |
| 20. | Spiders placed by Solitary Wasps in crotches of branching stems. (After Plate X. in Dr. Peckham’s “Solitary Wasps”) | 133 |
| 21. | Fox-terrier lifting the latch of a gate. (Drawn by Mr. Charles Whymper, after a photograph by Miss Alice Worsley) | 145 |
| 22. | Cage used by Dr. Thorndike. (After figure in “Animal Intelligence,” Psychological Review, 1898) | 148 |
| 23. | Diagram illustrating Dr. Thorndike’s Experiments. (Based on data given in his monograph on “Animal Intelligence”) | 150 |
| 24. | Wood ant. (From Shipley’s “Invertebrates.” A. & C. Black) | 207 |
| 25. | Beetle soliciting food from Ant. (After Wasmann. Enlarged) | 213 |
| 26. | Honey-pot Ant. (Enlarged) | 215 |
