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PLA TE. XVIL 
VORTICELLA URGEOLARIS: 
GENERIC CHAR ACTER. 
A fmall animal, with a vafcular cup; the mouth is at one end 
éiliated, and capable of being contratted; the ftem fixed. 
SPECIFIC CHARACTER. 
Single, with a fhort tail, and toothed mouth. 
This Animalcum is but barely perceptible to the naked eye, ap 
pearing as a {mall white fpeck; the microfcope difcovers the external 
covering to be fo tranfparent, that all the motions of the animal within 
are perfeétly diftinguifhable. It has a double rotatory inftrument, 
which, however, it'can conceal or thew at pleafure; and has alfo 
power to protrude the head and tail as at Fic. 1. or to contract them 
within the external coat or covering, as at Fic. 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 afhxes it to whatever 
fubftance is near; but when it fwims, it moves its tail backwards and 
forwards to-affitt it. 
They are found in river, or ftagnant, water. 
G FIG. 
