FLAGELLATE INFUSORIA AND ALLIED ORGANISMS. 87 



lines running transversely; these appear as if the dark 

 granules of Chilomonas had been elongated, although this 

 cannot be proved. These transverse stripes are seen more 

 distinctly in fig. 17, e. The pinching-in proceeds very 

 rapidly in a forward direction, so that in a few minutes the 

 two organisms are only attached to each other by a very 

 delicate thread, situated somewhat above the centre of the 

 body (fig. 17, f). This thread then breaks, and the result- 

 ing organisms are free. The relations of the nucleus and 

 contractile vacuole at the time of fission were obscured by 

 the movement of the organism and the opaqueness of the 

 protoplasm. 



Astasia, Ehrenberg (' Poggendorf s Annalen,' 1830, p. 

 508). 



Trachelius, Ehrenberg (' Die Infusionsthiere als vollkom- 

 mene organismen,^ Leipzig, 1838, p. 320). 



Peranema, Dujardin {' Hist. Nat. des Infusoires,' 1841, p. 

 352). 



Astasia, Dujardin (op. cit., p. 356). 



Pyronema (Duj.), Diesing ('Revision der Prothelminthen 

 Sitzungsbericht. d. k. Acad, zu ^yien,' 1865, Bd. iii, p. 327). 



There is some doubt as to the classificatory position of 

 these organisms, of which there appear to be three species. 

 Peranema and Astasia differ from each other in that the 

 former has a rounded extremity, whilst the latter has a tail- 

 like and pointed posterior end, but this difference is of 

 slight importance, since the forms are exceedingly variable. 

 Both Peranema and Astasia have the mouth situated ter- 

 minally, whilst in Pyronema it is ventral. 



Astasia trichophora, Ehrenberg. 



{?) Trachelius trichophorus, Ehrenberg ('Abhandl. d.Ak. 

 d. W. zu Berlin,' 1830, pp. 54, 65, 70 ; and ' Die infusions- 

 thiere als vollkommene organismen,' Leipzig, 1838, pi. xxxiii, 



Peranemaprotracta, Dujardin (' Hist. Nat. des Infusoires,' 

 Paris, 1841, p. 354). 



Peranema protractum, (Duj,), Perty ('Zur kenntniss 

 kleinster Lebensformen nach Bau, &c.,' p. 108). 



[f) Astasia limpida, Dujardin (op. cit., p. 357, pi. v, fig. 

 12). 



Astasia limjnda (Duj.), Carter ("Notes on the Freshwater 

 Infusoria of the Island of Bombay," ' Ann. and Mag. of Nat, 

 Hist.,' 2nd ser., vol. xviii, p. 115, pi. vi, figs. 45 — 48), 



