C 39 ] 

 PLATE XVII. 



VORTICELLA URCEOLARIS. 



GENERIC CHARACTER. 



A fmall animal, with a vafcular cup; the mouth is at one end 

 ciliated, and capable of being contracted ; the ftem fixed. 



SPECIFIC CHARACTER. 

 Single, with a fhort tail, and toothed mouthi 



This Animalcum is but perceptible to the naked eye, appearing as 

 a fmall white fpeck; the microfcope difcovers the external covering to 

 be fo tranfparent, that all the motions of the animal within are per- 

 fectly diftincl:. It hath a double rotatory instrument, which, however, 

 it can conceal or fhew at pleafure ; and it hath power to protrude the 

 head and tail as at Fig. i. or to contract them within the external coat 

 or covering, as at Fig. 2. — When the animal intends to difplay its 

 rotatory inftrument, it forces its tail through the hole at the extremity 

 of the outer coat, and affixes it to whatever fubflance is near ; but 

 when it fwims, it moves its tail backwards and forwards to affift it. 



They are found in river, or ftagnant, water. 



© FIG 



