110 NATURAL HISTORY 



small specimens. Figures 112 and 113 exhibit a side 

 and edge view of this animalcule, and figure 122, a 

 specimen nearly divided. 



The second, or white variety, described by Muller, is of 

 the same form as the green, except at the anterior ex- 

 tremity : he observed two dark spots, like eyes, but very 

 minute. Found near the surface of stagnant water, and 

 among confervas. Length, l-560th of an inch. 



187- Cbrcaria longicauda. {Euglena longicauda, E.) 

 The long-tail eye Cercaria. — This is a new species : it is 

 flat, like the last, of a bright green colour, with a red 

 eye. The tail is nearly the same length as the body, 

 which is very flexible, as it sometimes swims twisted like 

 a screw-driver. Length, l-200th of an inch. 



188. Cercaria setifera. The bristled Cercaria, — This 

 is a very scarce animalcule; it is found in impure salt- 

 water, and is smaller than the green Cercaria: the body 

 is spindle-shaped, the head terminated obtusely, and the 

 tail short and pointed, near to which a row of cilia, or 

 bristles, may be discerned. In swimming the body slowly 

 revolves. 



189. Cercaria hirta. The hairy Cercaria, — This is a 

 very remarkable animalcule, rather opaque, and of the 

 form shewn at figure 115, with its posterior extremity 

 furnished with two strong, short bristles. The body is 

 rough, and apparently covered with short hair at regular 

 intervals. In swimming, it revolves on its longer axis, and 

 resembles a wicker-basket : it is generally restless, and 

 difficult to follow except while feeding, when it remains 



