THE ANIMALS OF THE FRESHWATER AQUARIUM 127 



treatment than the more expensive Cambridge Natural History, whose ten 

 volumes are of unequal merit, and treat their respective subjects from very 

 different standpoints. Vol. ii. of this work (" Worms, Rotifers and Polyzoa," 

 London, 1896) may be consulted for the members of the " Worm " alliance, which 

 have been very briefly treated above. 



