Vorticellina.] THE INFUSORIA. 257 



hooks (or uncinate cilii), having the mouth and vibrating 

 wreath of cilii (of forty-eight to sixty-four) directed 

 upwards." It appears to feed upon the little granules of 

 the body of the fresh water polypi, drawn in plate vii. of 

 the Microscopic Cabinet. Fig. 228 and 229 are side views, 

 attached to a portion of a polypi ; fig. 230 is a top view. 

 Size l-570th to l-280th. 



392. TRICHODINA vorax. The voracious Trichodina has 

 an oblong, cylindrical, slightly conical body ; anterior part 

 convex, and crowned with cilii, the back rather attenuated 

 and smooth. Size l-570th. 



393. TRICHODINA grandinella (M.) The hail Tricho- 

 dina is nearly spherical, the back sharply attenuated ; a 

 wreath of cilii surrounds the truncated fore part. This 

 species is liable to be mistaken, by an inexperienced 

 observer, for a free Vorticella ; its true character appears 

 to be in its open wreath of cilii. Size 1 -1500th to 

 l-860th. 



Genus LXXXIX. UROCENTRUM. The top Animalcules 

 are free, have a tail-like style, but destitute of pedicle and 

 cilii, except a wreath anteriorly ; mouth aperture simple. 

 The internal organization, as far as it is known, is similar to 

 the preceding genera. Perfect transverse self-division has 

 been observed. Ehrenberg thinks the eyes, supposed to 

 have been seen by Miiller, were most probably the vestigia 

 of some of the cilii, none of which he appears to have seen. 



394. UROCENTRUM turbo (Cercaria turbo,M..) Mtiller's 

 Urocentrum is hyaline, and has an ovate, trilateral body, 

 with a style, or setaceous tail, one third of its length. 

 Ehrenberg says, " The little tail is not a separable Vorti- 

 cella-stalk, but an articulated style on the back perhaps a 



