242 ORDER FLAGELLATA-PANTOSTOMATA. 



abruptly truncate or excavate contour of the frontal border. No details respecting 

 the mode of inception of food are recorded, and, in the absence of all evidence as 

 to the existence of a distinct mouth, it appears desirable to retain the genus among 

 those forms most closely allied to it structurally, in which food-particles are known 

 to be ingested at all points of the periphery. The several species described are 

 very briefly characterized, the descriptions and accompanying drawings being the 

 result of an examination with a magnifying power of 400 diameters only, which is 

 altogether insuflicient for the full and exhaustive investigation of these minute 

 beings. 



Cyathomonas turbinata, From. 



Body elongate, turbinate, about twice as long as broad ; the posterior 

 extremity pointed, the anterior border truncate ; flagellum somewhat short, 

 not exceeding the length of the body ; parenchyma transparent, granulate ; 

 dividing by longitudinal fission. Length 1-1200". Hab. — Fresh water. 



Cyathomonas spissa, From. Pl. XIII. Figs. 46 and 47. 



Body elongate-ovate, or subcylindrical, about twice as long as broad, 

 pointed posteriorly, widest in the centre, and slightly narrowing again at 

 the truncate anterior margin ; flagellum short ; contractile vesicle situated 

 laterally in the anterior third of the body ; parenchyma granular ; dividing 

 by longitudinal fission. Length of body 1-2000". Hab. — Fresh water. 



The difference between this form and Cyathomonas inrbinafa, From., appears to 

 be too slight for specific separation. The figures given closely correspond with one 

 another, the contractile vesicle indicated in the present variety affording, indeed, the 

 only mark of distinction. 



Cyathomonas viridis, From. 



Body subcylindrical, about twice as long as broad, rounded posteriorly, 

 the anterior border truncate ; flagellum long and slender ; parenchyma 

 green, and granulate. Length 1-2000", Hab. — Fresh water. 



Cyathomonas alba, From. 



Size and contour identical with that of C. viridis, but the parenchyma 

 hyaline and less granular. This and the preceding form are evidently 

 varieties only of one species. 



Cyathomonas lychnus, From. 



Body hemispherical, truncate anteriorly ; posterior and peripheral 

 portion coloured green, the anterior border hyaline ; flagellum long and 

 slender. Diameter 1-3000". Hab. — Fresh water. 



Cyathomonas turbo, From. Pl. XIII. Fig. 48. 



Body top-shaped, tapering and pointed posteriorly, the anterior border 

 truncate ; flagellum very long and undulating, three or four times the 

 length of the body ; parenchyma granulate ; contractile vesicle antero- 

 lateral. Length of body 1-1600". Had. — Freshwater. 



