446 M i c 10 s comical Essays. 



To the naked eye it appears as a white moveable point ; but 

 when examined by the microfcope, a tail, projecting from the 

 lower part, is difeovered, and a double rotatory inftrument is feen, 

 which it can conceal or difcover at pleafure. It has been feen 

 and defcribed by moft microfcopical writers ; but as Mr. Baker's 

 feems to us to be the moft perfeft, we fhall principally follow his 

 account of it. 



He difeovered three fpecies of them, two of which are included 

 under the vorticella urceolaris. Fig. 33, 34, 35, are of the firft 

 fpecies ; Fig. 36, 37, 38, are of the fecond kind. The firft fort, 

 when extended, is about twice as long as it is broad. It is con= 

 tained in a fhell ; the fore-part of this is armed with four {harp 

 teeth, Or points ; the oppofite fide has no teeth, but is waved, or 

 bent, in two places, like the form of a Turkifh bow. At the 

 bottom there is a hole, through which it pu flies the tail. It 

 faftens itfelf by this tail to any convenient fubftance, when it in- 

 tends to ufe it's rotatory organs ; but when it is floating in the 

 water, and at all other times when not adhering to any body, it 

 wags the tail backwards and forwards fomething like a dog. 



We may confider it as divided into a head, thorax, and abdo- 

 men; each of which may be extended and contrafted consider- 

 ably : it can by dilating all three protrude the head beyond the 

 Ihell, or by contracting them, draw the whole body within the 

 fame. 



The head when extended divides itfelf into two branches, be- 

 tween which another part, a kind of probofcis, is puflied out ; 

 at the end of this are two fibrils, that appear when they are at 



reft 



