XI 1 CONTENTS. 



CHAPTER IV. 



PAOB 



The Tapeworm . . . . . . .45 



CHAPTER V. 



The Leech. Hirudo medicinalia. 



External characters Dissection Examination of transverse 



sections 49 



CHAPTER VI. 



The Earthworm. Lumbricus lerrestris. 



External characters Dissection of the earthworm Examination 



of transverse sections ....... 66 



CHAPTER VII. 



The Freshwater Mussel. Anodonta cygnea. 



The shell Dissection of the mussel Examination of transverse 



sections 89 



CHAPTER VIII. 



The Edible Snail. Helix pomatia. 



External characters Dissection of the snail . . . .117 



CHAPTER IX. 



The Crayfish. Astacus pallipes. 



External characters Dissection The arteries as seen in an in- 

 jected specimen ....... 140 



CHAPTER X. 



The Cockroach. Periplaneta americana. 

 Habits External characters Dissection 169 



