84 PROFESSOH O. BtJTSCHLI. 



has disappeared these two coalesce and increase. The newly- 

 formed vacuoles are not found exactly in the same position, 

 but they appear to occur alternately on each side. No 

 nucleus has yet been seen with any certainty. Reproduction 

 occurs, according to Perty, by longitudinal fission. 



Ghilomouas, Ehrb. (' Die Infusionsthiere als voUkom- 

 mene organismen,' Leipzig, 1838, p. 130). 



ChilomofiaSj Dujardin (' Hist. nat. des Infusoires/ Paris, 

 1841, p. 295). 



Cryptomo7ias, Perty (p. 165). 

 Ehrb. (p. 2). 



Zygoselmis, Fromentel (p. 2). 



Moderately elongated Flagellata, whose anterior end is 

 divided into two lips, between which is a distinct cytostome 

 (cell mouth), bounded by dark and closely-applied walls 

 which run far into the body. At the anterior end are two 

 fair-sized flagella. A contractile vacuole is present in the 

 upper lip, whilst a large nucleus is situated posteriorly. Re- 

 production takes place by longitudinal fission. 



Chilomonas paramecium, Ehrb. (op. cit., p. 30, pi. ii, 

 fig. 6). 



(?) Cryptomonas curvata, Ehrb. (p. 40, pi. ii, tig. 16). 



(?) „ cylindrica, Ehrb. (p. 42, pi. ii, fig. 19). 



„ polymorpha, Perty (p. 162, pi. xi, fig. 



A— H.) 



Chilo?nonas granulosa, Dujardin (' Histoire nat. des Infu- 

 soires,' Paris, 1841, p. 295, pi. iii, fig. 15). 



Chilomonas paramecium, Ehrb. (Schneider, A., " Beitrage 

 zur Naturgesch. der Infusiorien," p. 199, p. ix, fig. 25; 

 'Arch. f. Anat. und Physiol.,' 1854). 



(?) Chilomonas obliqua (Duj.), Fromentel (p. 331, pi. xxiii, 

 fig. 35). 



Zygoselmis nehulosa (Duj.), Fromentel (p. 320, pi. xxiii, 

 fig. 25). 



These organisms are amongst the most frequently occur- 

 ring Flagellata, particularly in somewhat foul ponds and in 

 infusions. In infusions, however, only a colourless kind are 

 found, generally as a dark variety enclosing a great number 

 of large and dark granules — the true Chilomonas parame- 

 cium of Ehrenberg, or the Chilomonas granulosus of Du- 

 jardin. The brown or green variety, to which both species 

 of Ehrenberg's Cryptomonas belong, are only found in ponds. 



The shape of the organism is very variable (Plate 



