628 



Microscopical Essays. 



The circular bodies which project from them have much the 

 refemblance of wheels, and feem to turn round with confiderable 

 velocity, by which means a very rapid current of water is brought 

 from a great diftance to the mouth of the little creature ; as thefe 

 wheels are very tranfparent, except the edge, which is fet with 

 fibrillar, (as cogs to a wheel) it is difficult to determine how they 

 are turned about, or what is their real figure, whether they are 

 flat, concave, or conical ; be this as it may, they are protruded 

 from a couple of tubular cafes, in which they can be again re- 

 tracted, at the will and pleafure of the animal. They do not 

 always turn the fame way, nor with the fame velocity ; they will 

 fometimes move in contrary directions, fometimes both one way. 

 The figure varies, from the degree of their protrufion, and from 

 other circumftances. They appear fometimes like minute oblong 

 fquares, rifing from the periphery of a circle ; at other times they 

 terminate in {harp points, fometimes they are curved, bending 

 the fame way like fo many hooks ; now and then the ends appear 

 clubbed, or in appearance like a number of little mallets. 



When the fore- part of this creature is firft feen to open or 

 divide, the parts, which when fully protruded referable wheels, 

 feem only like a couple of femicircles, the edges whereof are fet 

 with little fpicuke, having all a nimble and continual vibrating 

 motion upwards and downwards, whereby the water becomes 

 agitated, each wheel being in this cafe doubled, or like a round 

 piece of paper folded in the middle. 



When the wheels are in motion, the head appears very large 

 in proportion to the fize of the animal ; and though it is then 

 cvery-where tranfparent, yet a ring or circle, more particularly 



remark- 



