220 AQUATIC MICROSCOPY FOR BEGINNERS. 



from among the leaflets, and may be captured by the 

 dipping-tube. If left on the table near a window 

 they will, like most microscopic creatures, both plants 

 and animals, in a short time, collect on the lighted 

 side. 



The reader will, of course, not expect that all the 

 genera and species are included in this little book. 

 He will obtain many whose names he cannot hope to 

 learn in this short account. He caft, however, know 

 them to be Rotifers by the presence of the mastax, 

 which makes them one of the most easily recognizable 

 groups of microscopic animals, and they form one of 

 the most interesting classes of creatures for micro- 

 scopical study. Few of our American forms have 

 been carefully investigated, and there is no American 

 treatise on the subject to which the reader can be re- 

 ferred. The only work on the Rotifera in. the English 

 language is Hudson & Gosse's "The Rotifera; or 

 Wheel-Animalcules," published in London, a valuable 

 monograph and one which every student of micro- 

 scopic pond-life should possess, although it does not 

 deal extensively with American species. The "Wheel- 

 Animalcules" of this country form an extensive field 

 for scientific research and one that should be culti- 

 vated. There is room here for many discoveries, and 

 likewise an opportunity to 'add greatly to the world's 

 store of scientific information. 



In using the following Key, the reader should bear 

 in mind that the mucilaginous sheath of some of the 

 Rotifers is usually colorless, and rather d.ifificult to see 

 distinctly unless it have particles of dirt, or of .other 

 extraneous matters, adherent to it. At times, how- 

 ever, it may be almost as conspicuous as the animal 



