134 DESCRIPTION OF {^Polygaitrica. 



scarcely variable, with a filament, having a thicker and more flexible 

 base, than that of 3Ionas, the free extremity only being moved. 



This genus is as yet but artificial, and provisional indeed, true 

 monads perfectly developed, may possess a filament, with a thicker 

 base ; and again, the constant outline of the body, may be the con- 

 sequence of the presence of an integument, in which case the ani- 

 malcules in question would be referable to the family 2'hecamonadina. 

 Movement slow and unifonn. 



It is to be regi'etted, that Dujardin uses this generic name, as 

 Ehrenberg previously employed it to designate certain ciliated ani- 

 malcules, which correspond but partially with those of Dujardin, 

 under this title. To render this work complete, they are introduced, 

 and, we hope the reader will not be confused. Dujardin observes, 

 that ''the genus Cychjdmm (Ehr.), contains monads also, and very 

 probably some of those to which I have applied the same ' generic' 

 name." 



CrcLiDKTM noduiositm. (Duj.) — Body flattened, discoid, with rows 

 of nodules and vacuolse, movement extremely slow, Length 1 -5200th. 

 Found in water from the Seine. 



C. abscissum. (Duj.) — Body membranous, lamelHform, truncated 

 posteriorly, filament rigid, movement slow, regular. (P. 21. f. 15.) 

 Length 1-1 040th. 



C. crassum. (Duj.) — Body oval, thick and rounded, filament 

 thickened at its base, and rather sinerous ; movements more active, 

 zigzag. Length 1 -1090th. Length of filament 1 -600th. 



C. distortrum. (Duj.) — ^Body oval, flat, nodular, irrcgulai'ly bent 

 wdth a tumid border. Length l-1800th to l-800th. (P. 21. 

 f. 14.) 



" This species is perhaps but one phase of develoj)ment of 

 Ilonas lens, it was found in Seine water, kept during three months. 

 "When young it has the form of a disc, with a tumid and nodular 

 margin; when, however, it has grown larger, it becomes twisted 

 upon itself, and its movement irregular. Some individuals offered a 

 certain affinity with the Trepomonads, which favoui-s the opinion 

 already advanced, that the majority of the Monad ina, are but modi- 

 fications of one or of several types." 



Genus Ceecomonas, (D.) — Body rounded or discoid, tubercidar, 



