INFUSORIA. 151 



number from two or three up to forty or fifty or more. 

 Each Infusorium has a narrow, yellowish - green band 

 down each side of the somewhat egg-shaped body, and 

 two long, fine flagella at the broader front end. The 

 colonies are common in early spring in shallow pools 

 with Algae. 



15. 122. Uvella. Fig. 123. Trachelocerca. 



15. TRACHELOCERCA (Fig. 123). 



This will probably be a greater surprise to the begin- 

 ner the first time he sees it than any other common In- 

 fusorium, on account of the remarkable neck, which can 

 be stretched out to five or six times the length of the 

 body, and drawn back until it almost entirely disap- 

 pears. The body, without the neck, is somewhat spin- 

 dle-shaped, and occasionally ends in a short, tail-like part. 

 The Infusorium may often be concealed in a mass of 

 fragments or a heap of dirt, while only that wonderful 

 neck is visible, stretching and bending and writhing like 

 a colorless snake, as it searches the slide for food. The 

 end of the neck is rather pointed, and bears the mouth 

 at the tip. The whole Infusorium is covered with fine 

 cilia. It is quite common. 



16. AMPHILEPTUS (Fig. 124). 

 This is one of the largest of the Infusoria, sometimes 



