HOMOOENEA. 453 



ORDER II. 



HOMOGENEA. 



The body of the Homogenea presents neither viscera nor other 

 complication, and is frequently destitute of even the appearance of a 

 mouth. 



The first tribe comprises those which, with a gelatinous body 

 more or less contractile in its different parts, still present external 

 organs consisting of cilia more or less strong. 



When they have the form of a horn (cornet), from which the cilia 

 issue as in the Polypi, called VorticeUce, we have the 



Ureolaria, La?n. 



When the body is flat, and these cilia are at one extremity. 



Trichoda, 



When they surround the whole body, 



Leucophra, 



When some of them are stout, and represent species of horns, 



Kerona, 



When these pretended horns are elongated into threads, 



HiMANTOPES, 



The second tribe consists of those which exhibit no external organ 

 whatever, if we except a tail. In 



Cercaria, Mull., 



The oval body is in fact terminated by a thread. To this genus be- 

 long (among others) those animalcules which are observed in the 

 semen of various animals, and on which so many fantastic theories 

 have been founded. 



When this thread is forked, as is sometimes the case, we have the 

 FuRcocERCA of Lamarck. 



Vibrio, Mull., 



Where the body is round and slender like a bit of thread. 



It is to this genus that belong the 



V. cjlutinis et aceti, or the pretended Eels that are seen in vi- 

 negar and paste. Those that inhabit the former are frequently 

 perceptible to the naked eye. It is asserted that they change 

 their skin, consist of two sexes, produce living young ones in 

 summer, and eggs in autumn. Freezing will not kill them. 

 The others make their appearance in diluted paste. 



