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 ...................... 



LESSON XIX. 



SPIROGYRA ........ .......... 194 



LESSON XX. 







MONOSTROMA ... ......... 2OI 



ULVA ................. ..... 2O3 



LAMINARIA, &C. .............. 203 



