TABLE OF CONTENTS xv 

 LESSON XIIL 



FACE 



SPECIES AND THEIR ORIGIN : THE PRINCIPLES OF CLASSIFICA- 



TION 137 



LESSON XIV. 



THE FORAMINIFERA . I48 



THE RADIOLARIA 152 



THE DIATOMACE^ 1$$ 



LESSON XV. 



MUCOR 158 



LESSON XVL 



VAUCHERIA 169 



CAULERPA 175 



LESSON xvn. 



THE DISTINCTIVE CHARACTERS OF ANIMALS AND PLANTS . . 1 76 



LESSON xvin. 



PENICILLIUM 184 



AGARICUS 191 



LESSON XIX. 



SPIROGYRA 194 



LESSON XX. 



MONOSTROMA 201 



ULVA 203 



NITELLA 203 



