THE FISHES, MOLLUSOA, AND OTHER OBJECTS- 61 



any standing water, is the Rotifer vulgaris (Fig. 54). 

 Some, of them, as the Melicerta ringens, and others, 

 surround their fixed bodies with a caddis-worm 

 like tube, made up of small pellets. Fig> 54- 

 Perhaps the Floscularia is one of 

 the most beautiful of all the wheel- 

 animalcules. Like the rest, it is 

 usually to be found adhering to the 

 fresh-water plants. It has a gela- 

 tinous case, and is exceedingly trans- 

 parent, so much so that unless the 

 eyes aro sharp and to some degree 

 trained what to look for, you are apt 

 to pass it by. Frequently its pre- 

 sence may be known by a number 

 of minute algae and other substances 

 attached to it. Its food consists 

 of small algae, or rather of their 

 spores. When searching for them, Rotifer vulgaris. 

 it stretches itself out of its case, and expands its 

 " wheel," or ciliated disk, which consists of a number 

 of long and delicate tentacles spread out in fan-like 

 form from the lobes which surround the mouth. In 

 the species figured (F. cornuta) there are five of these 

 lobes, as well as the so-called horn (a), whence the 

 specific name. You may notice, if you watch the 

 motions of this creature carefully under the micro- 

 scope, the currents running into and out of the 

 mouth. The ova are usually deposited at the base 

 of the foot. 



