TABLE OF CONTENTS xv 



LESSON XIII. 



PAGE 



SPECIES AND THEIR ORIGIN : THE PRINCIPLES OF CLASSIFICA- 

 TION 137 



LESSON XIV. 



THE FORAMINIFERA 148 



THE RADIOLARIA . 152 



THE DIATOMACE/E 155 



LESSON XV. 



MUCOR 158 



LESSON XVI. 



VAUCHERIA 169 



CAULERPA 175 



LESSON XVII. 



THE DISTINCTIVE CHARACTERS OF ANIMALS AND PLANTS ... 176 



LESSON XVIII. 



PENICILLIUM 184 



AGARICUS igi 



LESSON XIX. 



SPIROGYRA 194 



LESSON XX. 



MONOSTROMA 2OI 



ULVA 203 



LAMINARIA, &C 2O3 



