'6 LAKES AND RIVERS. 



CHAPTER PAGE 



VIII. OUR AQUATIC MOLLUSCA. SPH^ERIUM, PISI- 

 DIUM, UNIO, PEARL MUSSEL, ANODONTA, 

 DREISSENA, NERITINA, PALUDINA, VAL- 

 VATA, PLANORBIS, LIMNEA 191 



IX. Six MONTHS OF BROOK AND POND LIFE IN 



SUSSEX ... 220 



