OF animalcui.es. 65 



this species ; and as his description contains some re- 

 marks applicable to the group, it is here appended, slightly 

 abridged. 



This wonderful animalcule was discerned by Mr. A.n- 

 deron. It is extremely slender, and often 150 times 

 longer than broad : the body is nearly straight ; the ends 

 are slightly curved in opposite directions, and resemble 

 each other so closely that it is difficult to distinguish 

 them. Some appear covered with rings ; in others, the 

 rings cross each other obliquely, and in some the body 

 seems covered with scales. As it is incapable of bending, 

 it either moves forward in the direction of its length, or 

 if desirous of moving in an oblique direction, it describes 

 the arc of a circle with one end, and then with the 

 other, alternately, making each extremity the centre of 

 rotation. They were discovered in a large ditch running 

 into a river near Norwich, the bottom of which was 

 covered with them to some thickness : when first exa- 

 mined, being motionless, they were taken for vegetable 

 fibres, but on keeping them under the microscope, with- 

 out disturbing, and occasionally viewing them, they were 

 seen to move, and form themselves into companies, in 

 various forms. After putting a large spoonful of the 

 green water, containing these animalcules, into a 

 glass vase, and gently filling it with clean water, with- 

 out disturbing those at the bottom, they formed them- 

 selves into a column, and in a few days ascended to the 

 surface. (I may here remark, that they usually ascend 

 on that side of the vessel which is most exposed to the 



