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University of California Publications in Zoology [VOL. 19 



Seldom does the sulcus extend far enough forward to modify the 

 regularity of the anterior end, which is fairly constant in form, much 

 more so than the posterior end. This sulcus is a furrow or depression 

 which cleaves the body on one side, which side may consistently be 

 called sulcal or adsulcal, analogous to ventral, as opposed to absulcal, 

 which is analogous to dorsal. The secondary sulci usually branch 

 from the chief longitudinal sulcus, the resulting cusps being variable 

 in size, shape and permanence. At times the general form becomes 

 spherical and globular, the posterior end truncated, or ovate and 

 conical, with acute posterior end, the sulcus being faint in both cases. 



Fig. A. Pseudopodia of Collodictyon. Diagrammatic. X 1000. 1-2. Lobose. 

 3. Undulate. 4. Digitate. 5. Filose. 1-5. From the sulcus. 6. From all parts of 

 the surface. 



The four flagella are paired, each pair arising from a single basal 

 granule, the two granules being embedded in the irregular chromatoidal 

 blepharoplast which is surrounded by a granular, less darkly staining 

 archoplasm or modified cytoplasm. The flagella are typically whip- 

 like, in length averaging that of the major axis of the body, at times 

 a little longer, measuring in one instance 68 to TOyu,. They taper 

 toward the tip. France (1899) used zinc chloride to bring out their 

 full length and further observed their base to be granular. Language 

 is inadequate to describe the beauty of their elegant backward curves. 

 They function both in pulling and propelling the body forward, in 

 attachment to the substrate while the organism rotates on its major 

 axis, as a tactile organ for directing locomotion, and actively in offense 



