GENUS CHILOMONAS. 425 



longitudinal fission was frequently observed. The two flagella of this species, when 

 the animalcule is at rest, are described by Biitschli as being folded loosely across one 

 another, as represented at PI. XXIV. Fig. 51. 



Quite recently (August 1879), the author has had an opportunity of examining 

 this animalcule, and while able to confirm Butschli's more general account of its 

 structure, has elicited certain data concerning the comportment and insertion of the 

 flagella that have necessitated a slight modification of the diagnosis previously pre- 

 pared. In no instance was it made clear that these organs were inserted otherwise 

 than close to one another, immediately beneath the lip-like prominence, while at the 

 same time the lower of the two, when the animalcule was at rest, was thrown into 

 a loose spiral coil in the same manner as the homologous appendage of the genus 

 Oxyrr/iis, and being used in a similar manner as an organ of attachment. A turn of 

 this coil, issuing from behind the profile of the animalcule, often presented the appear- 

 ance of a distinct and separately inserted flagellum, and it is probably upon such a 

 deceptive optical aspect that Biitschli has based his interpretation of the remote 

 insertion of the flagella in this species. In addition to the likeness to Oxyrrhis, 

 conveyed by the convolute disposition of the flagellum in question, the movements 

 of Chilomonas paramcedum in the water accord to a considerable extent with those of 

 the last-named type. These consist, in a similar way, of an intensely active condition 

 in which the animalcule rushes to and fro, though with the anterior end foremost, 

 at a speed too rapid almost for the eye to follow, while at the next moment it comes 

 as it were abruptly to anchor, with its body perfectly quiescent and one flagellum 

 thrown into a coil and adherent to the glass slide or covering glass, while the other 

 maintains a vibratory motion. 



The figures of this species included in Stein's recently published volume * accord 

 substantially with those given by O. Biitschli, his interpretation of the insertion of the 

 flagella, however, being identical with that maintained by the present author. 



Chilomonas cylindrica, Ehr. sp. PL. XXIV. FIG. 50. 



Body moderately persistent in form, elongate, subcylindrical, straight, 

 about three and a half times as long as broad ; endoplasm yellowish- 

 brown, enclosing irregularly scattered granules; anterior border obliquely 

 emarginate ; the oral aperture excentral, continuous with a short, wide 

 reticulate pharyngeal tract, which extends backwards along the ventral 

 margin to about one-quarter of the entire length of the body ; the two 

 flagella inserted close to one another above the oral aperture ; contractile 

 vesicle situated immediately above the pharyngeal passage ; endoplast 

 spherical, located at a short distance from the posterior extremity. Length 

 of body 1-500", and less. 



HAB. Pond water, and amongst decaying vegetation. 



This species would appear to be synonymous with the Cryptomonas cylindrica of 

 Ehrenberg and the Cryptomonas polymorpha, in part, of Perty, though, as already 

 intimated, Butschli has figured and described it as a variety only of Chilomonas para- 

 mczcium. Setting aside details of external contour, which are subject to variation, the 

 structural characteristics of the two are, however, essentially distinct. The position 

 of the oral aperture in this species is eccentric instead of central, the pharyngeal 

 tract follows the same eccentric course and is much shorter and wider. The 

 substance of the endoplasm of the two is likewise distinct, the symmetrically granular 

 pattern being replaced in the present form by a yellow coloured stroma described by 

 Butschli as consisting of two even parallel layers continuous throughout the body 

 and separated from one another by a clear linear interspace- this circumstance, 



* 'Infusionsthiere,' Abth. iii. Heft i., 1878. 



