174 AQUATIC MICROSCOPY FOR BEGINNERS. 



need have no trouble in knowing where to class the 

 worms; yet with another division of the group the ob- 

 server may not fare so well. 



These worms have flattened, usually almost opaque 

 bodies, with the entire surface densely clothed by fine 

 cilia, and, probably on account of the stir and disturb- 

 ance which the cilia make in the water, naturalists 

 have classed the worms together under the name of 

 the Turbelldria, from a Latin word meaning a stir or 

 bustle. Their motions are rapid and apparently with- 

 out effort. They glide smoothly and swiftly over sub- 

 merged objects, or not rarely swim back downward on 

 the surface of the water. Some of these Turbelldrians 

 are shown in Fig. 145. 



There is still another group of common aquatic 

 worms, but to recognize them will give even the 

 beginner very little trouble. They are often rather 

 sluggish in their movements; they have a perfectly 

 transparent, usually smooth, thread-like body, which 

 is apparently truncate in front, and prolonged posteri- 

 orly in a sharpened, point-like tail. They have no 

 bristles nor cilia, and they rather closely resemble a 

 microscopic eel; indeed the scientific narne, Anguillula 

 means a little eel. These are closely allied to the 

 well-known vinegar eels and to the equally common 

 paste-worms. 



Many members of all these classes are found in the 

 superficial sediment of shallow ponds, in the crevices of 

 wet and water-soaked logs, under submerged stones, 

 among the leaflets of Myriophyllum, Sphagnum and 

 other water-plants. Sphagnum seems a favorite" place 

 for several kinds. I have obtained members of five 

 genera, JVdis', PrisNna, D^ro, Ckcetogdster, and ^olo- 



