TRACHELOCERCA. 131 



plants. One genus is named the swan-neck 

 animalcule, from the extreme length of that 

 part in some of the species ; indeed, they may 

 be called all neck, for the body is small com- 

 paratively, and they are more frequently seen 

 with the neck alone projecting from the edge of 

 a leaf. Trachelocerca olor (Drop III. fig. 6) has 

 a spindle-shaped body, with a very long flexible 

 neck, dilated at the end, where the mouth is 

 situated. The animal creeps at the bottom of 

 the water, or on the leaves, and is constantly 

 moving its graceful neck in all directions amongst 

 the weeds : when two or three are feeding close 

 together, it is curious to watch the actions of 

 this flexible member. 



Another singular creature, somewhat similar 



