Microscopical Essays. 



6 35 



332. Vorticella Flofculofa. Fig. 51 and 52, Plate XXVI. . 



Vorticella caudata aggregata, oblongo-ovata, difco dilatato 

 pellucido. With a tail aggregated, of an oblong oval fhape, 

 with a dilated pellucid difc. 



To the naked eye it appears as a yellow globule, adhering to 

 the ceratophyllon (a) like a little flower (b), or like a heap of yel- 

 low eggs. By the microfcope they are difcovered to be a con- 

 geries of vorticellas, conftituting a fphere from a mouldy center. 

 They either fmgly, or many of them together, extend and con- 

 tract their little bodies, and by means of the difc excite a vortex 

 in the water. 



Sometimes they quit the fociety, and aft fingly; they may 

 then be obferved more eafily, and will be found to conlift of 

 three parts, a head, abdomen, and tail. The head is often fo 

 drawn back into the abdomen (d), that no veflige of it remains ; 

 but it exhibits a broad difc (landing out, oPa kidney-fhape. The 

 abdomen (d) is an oblong, oval, pellucid, replete with obfcure 

 interlines, amongft which are one or two remarkable black oval 

 fpots (e) ; the tail is fharp, and as long again as the abdomen, 

 rough and annulated, or altogether fmooth. 



333. Vorticella Citrina. Fig. 53, Plate XXVI. 



Vorticella fimplex, multiformis, orificio contraclili, pedunculo 

 8?quali. Simple, many-fhaped, with an orifice that it can con- 

 tract, and equal-fized foot-ftalk. 



4H2 



The 



