4 THE AMERICAN MONTHLY [Jan., 



thither as is its usual habit came near a worm of one 

 segment. With a suddenness that was unexpected, the 

 worm bent its head, darted forward, two large flaps at 

 the mouth opened out and the Urostyla was gulped down. 

 The curious part of it, however, was that within a few 

 seconds after entering the stomach of the worm the Ur- 

 ostyla dissolved away. Without witnessing the actual 

 capture of its prey, it could not be told upon what this 

 worm fed, as the contents of the stomach were an undis- 

 tinguishable mass. Generally animalcules which are cap- 

 tured by others remain for a considerable time before 

 being dissolved by the digestive fluids. 



What the round object in the head represents, I have 

 not been able to ascertain. It has a bright center and 

 dark border as the drawing represents it. 



Gfreat voracity is characteristic of these worms. Some 

 have been observed swallowing numerous sand grains 

 with the vegetable matter constituting their ordinary 

 food. 



The Crustacea are well represented in these tanks at 

 nearly all times by such genera as Daplmia, Cyclops, 

 Cyhris and others. All of these are ravenous feeders 

 much to the discomfiture of the microscopist whose 

 choisest specimens they cause to disappear. 



Zoophytes have an example in the beautiful Plumatella 

 repens, often covering the sides of tanks or the under 

 side of leaves with a network of branching tubes to the 

 extent of several inches. They are easily discerned by 

 the unaided eye, but it is difficult to detach the tubes 

 without injuring the animals within. 



Hydra fusca and Hydra viridis representing the Coelen- 

 terata appear in the same situations and also attached 

 to various water x>lants. While plentiful at times, there 

 are occasions when none at all can be found. A prac- 

 tised eye easily finds them without a magnifier. They 

 feed upon water-fleas, Nais worms, and indeed, any kind 



