LIST OF ILLUSTRATIONS. 



FIGURE PAGE 



1-8. Amoeba 2 



9. Paramecium aurelia ... . ... 4 



10. Vcyrticella 9 



11. Hydra : Diagrammatic longitudinal section 14 



12. „ Section of the body-wall, highly magnified ... 16 



13. Fasciola hepatica : Diagrammatic figure of the digestive, ex- 



cretory, and nervous systems 28 



14. „ The reproductive system 30 



15-19. „ A series of stages in the life-history . . . . 84 



Fig. 15. The free-swimming embryo 

 „ 16. A sporoeyst, containing redise 

 „ 17. A young redia 

 ,, 18. An adult redia, containing a daughter-redia 



and cercarise 

 ,, 19. A free cercaria 



20. Hinido medicinalis : The ventral surface 40 



21. „ Diagrammatic figure of the vascular, renal, re- 



productive, and nervous systems . . 40 



22. „ Diagrammatic transverse section through the 



middle of the body 52 



23. Lumbriciis terrestris : Longitudinal vertical section through 



the anterior part of the animal .... 61 



24. „ Plan of the reproductive organs . . . . 67 



25. „ Diagrammatic transverse section through the 



middle of the body 71 



26. Anodonta cygnea : Dissection from the right side, to show the 



heart and giUs 85 



27. „ Dissection from the right side, to show the diges- 



tive, circulatory, and renal systems ... 91 



28. ,, Diagrammatic transverse section through the 



middle of the ventricle 101 



29. Helix pomatia : Dissection from the right side to show the 



mantle-cavity 109 



80. „ Dissection from the right side, to show the 



digestive and reproductive systems . . . . 114 

 31. „ Section along the axis of the shell, transverse to 



the foot 123 



82. AstaciLS fluviatilis : Transverse section through the abdomen . 127 



33. „ The oral appendages 132 



34. „ Diagrammatic transverse section through the 



thorax 136 



35. „ Dissection of a male from the right side . . 140 



