614 



SYSTEMATIC HISTOEY OF THE INFUSOEIA. 



revolving:. Cilia often appear longer in 

 front. Found by Dujardin and Perty in 

 decomposing marsh-water. 



A. cava (Perty). — Oval, sliglitly iiTe- 



gular; convex above, flat beneath, or 

 rather concave. Thickly ciliated all 

 over. 1-670". Amongst Lenmse. 



Genus HABEODON (Perty). — Body subcyHndrical, rather bent ; thickened 

 posteriorly, and mostly tnincate in front. Mouth anterior, with a veiy deh- 

 cate dental apparatus. Anus posterior. Cilia in longitudinal rows. 



This genus, created by Perty, is placed by him in juxtaposition with Pro- 

 rodon, with which and CliUodon, Nassida, and a new genus, Cydogramma, 

 it constitutes a family called Decteria. 



Habeodon ciirvatus = Enchehjs Pupa 

 (?) (Midi.). — Colour usually grey or pale 

 green, with nmnerous moleciiles and 

 vesicles; anteriorly it is hyaline, and 



posteriorly it presents a round clear 

 space (an anus ?). Movements slow. 



1-390" to 1-132". 

 Cliara, &c./Bern. 



In spiings, with 



Genus ACROPISTHIUM (Perty) (XXYIII. 61).- 

 rior flap, or rounded o£P ; pointed behind. 



AcEOPiSTHiUM mutabile. — Hyaline, 

 with darker vesicles and molecules. 

 Movements very rapid, revolving. Cilia 

 cover the entire surface, very fine, usually 



-Cii'cular, with an ante- 



more perceptible anteriorly. The figure 

 varies much. Mouth in front (?). 1-360" 

 to 1-320". Uncommon. 



Genus BJEOIN^IDIUM (Perty) (XXYIII. 52-54).— Small, subcylindrical ; 

 cilia at anterior end large ; movement sluggish. 



movement. A slight depression some- 



times perceptible on one side, in the 

 position of the mouth. Fission trans- 

 verse. 1-840" to 1-660". Amongst 

 Charse, but rare, in Switzerland. 



B^oiSTTDiuiM remigans. — Usually pris- 

 matic and roimded; often rather 

 wrinkled; hyaline, but nearly always 

 filled with green corpuscles. Cilia 

 generally distributed ; the large anterior 

 ones simulate pedal organs in their 



Genus OPISTHIOTBICHA (Perty) (XXYIII. 55-57).— Small, elongated- 

 cyUndiical or ppiform ; cilia distributed over the body, very fine, some of 

 those on the posterior extremity large, ciliary action sluggish. 



Large posterior cilia from two to three 

 in voung specimens, five to six in old. 

 1-900" to 1-440". In marsh- or bog- 

 water. Bern, &c. 



Opisthioteicha tenuis (xxvin. 55- 

 57). — Colom-less or slightly green, with 

 delicate vesicles and molecules in the 

 interior. Swims very ra^idl}^, revolv- 

 ing at the same time on its long axis. 



Genus SIAGOIN'THEBIUM (Perty) (XXYIII. 62, 63).— Yery small, ex- 

 tended anteriorly, thickened posteriorly ; with a long stiff bristle extended 

 backwards on one side of the anterior extremity. 



SiAGOXTHEEiUM temie. — Seen on the delicate, with internal molecules and 



wdder side, elongated ovate; anterior vesicles. Scarce in pools. Bern, with 



prolongation directed forwards from the Hysginum pluviale. 1-900" to 1-760". 

 smaller subcylindrical half. Extremely 



Genus MEGATRICHA (Perty) (XXYIII. 58-60).— Yery smaU, clothed 

 with long, scattered and slowly-moving cilia. Body entire, or divided incom- 

 pletely into two unequal portions. " These are the most delicate and simple 

 of all the Ciliata." 



1-1440". Un- 



Megateicha Integra. — Undivided, 

 colourless, with long, delicate cilia. 

 Yery possibly Chcetomonas Ghbuhfs be- 



longs 



to this species, 

 common. 



M. imrtita (xxvni. 68-60). 



-Divided 



