WATER FLEAS. 135 



shown at a, the oesophagus at b, the stomach at c, the 

 intestines at d, the muscles at e, the mouth at h h, 

 the withdrawn tentacles at i, the lophophore, or 

 " crest-bearer," which is covered with cilia, at m. The 

 same kind of horse-shoe shaped lophophore, or crest, 

 surrounds the mouth of Pltimatella. 



Fig. 96. 



Cyclops, showing female with egg-bags ; the young, and a single 

 jointed antenna. 



Cyclops and water fleas (Daphnid) ought to be en- 

 couraged in every fresh-water aquarium. Their food 

 consists chiefly of decomposing aquatic vegetation, 

 desmids, &c., whilst their own wonderful powers 

 of reproduction will always people the water with 

 living food for the higher animals. Most fishes and 

 amphibians live to a very great extent upon these 

 creatures. Cyclops (Fig. 96) is a very common 

 aquatic object, and the female may be seen with the 

 naked eye. So prolific is she that it is stated she 



