36 University of California Publications in Zoology [Vol. 16 



vent. fl.). and the posteriors {post. fl.). The antero-lateral flagellum 

 (ant. lat. fl.) arises from the blepharoplast, crosses obliquely anteriorly 

 to the opposite side, crossing its mate of the opposite side in the middle 

 line and enlarging at their junction in an anterior chromatic granule 

 (ant. chiasma). It follows the curvature of the ventral margin and 

 adjacent anterior peristome to the posterior end of that structure, 

 where it enlarges in a basal granule (lat. bas. gr., fig. A) at the point 

 of its emergence from the cytoplasm. The intracytoplasmic part of 

 this flagellum (intracyt. lat. fl.) is easily confused with the adjacent 

 heavy peristome which it parallels and by which it is usually obscured. 

 It is more deeply stained than the exposed free flagellum. 



The postero-lateral flagellum (post. lat. fl., fig. A) passes through 

 the cytoplasm posteriorly from the blepharoplast (pi. 5, fig. 8) parallel 

 to the axostyle along its ventral surface to about the level of the pos- 

 terior border of the nucleus where it crosses the posterior peristome. 

 Here it swings obliquely outward 15°-20° from the axostyle, becomes 

 heavier and stains more deeply, and emerges from the cytoplasm at 

 or usually somewhat within the postero-lateral margin. Its varying 

 point of emergence is doubtless due to the mobility of this region. 

 There is no basal granule here as a rule, though in some individuals 

 (pi. 5, fig. 3) a small one is present. 



The free ventral flagellum (/r. vent, fl., fig. A) emerges on the 

 ventral face shortly behind the blepharoplasts on the ventral side of 

 the axostyle. A darker region (pi. 5, fig. 8) is often present on the 

 base of each flagellum at this point parallel to the axostyle. It does 

 not seem to be a thickened part of an axostyle as figured by Wenyon 

 (1907) and Bensen (1908), but rather independent of, but ventral to 

 it. We are unable to trace its connection thence with the blepharo- 

 plast as in the case of the other flagella. These flagella are .stated to 

 be heavier and more active by Wenyon (1907). We find no increased 

 size, though their position gives a greater freedom of movement and 

 they are more active than the other flagella, except the posteriors, and 

 are sometimes seen anteriorly directed (pi. 6, figs. 28, 29). 



The posterior flagellum (post, fl., fig. A) is a direct continuation 

 of the axostyle. In the case of the single axostyle prior to the approach 

 of mitosis there is one flagellum from each side of its tip (pi. 5, 

 fig. 1) at which there may be a basal granule, but this is not always 

 present. After the division of the single axostyle to form two (pi. 5, 

 fig. 6), one flagelluna and one basal granule go with each daughter 



