48 



COLLEGE ZOOLOGY 



Order 4. ' Cystoflagellata. — Mastigophora with two flagella, 

 one resembling a tentacle, the other lying in the gullet. Ex- 

 amples : Noctiluca (Fig. 31), 

 Leptodiscus. 



Enormous numbers of Nocti- 

 luca are often found floating 

 near the surface of the sea, giv- 

 ing it the appearance, as Haeckei 



cr.i/.^ 



Fig. 30. — Peridinium 

 divergens, a Dinoflagel- 

 late. a, flagellum of longi- 

 tudinal groove ; b, flagel- 

 lum of transverse groove; 

 cr. v, contractile vacuole 

 surrounded by formative 

 vacuoles; n, nucleus. 

 (From the Cambridge Nat- 

 ural History, after Schiitt.) 



Fig. 31. — N octiluca mili- 

 aris, a Cystoflagellate. 

 (From Weysse, after Cien- 

 kowski.) 



says, of "tomato soup." At night they are phosphorescent, 

 emitting a bluish or greenish light. 



3. Class III. Sporozoa 



a. Monocystis 



Monocystis (Fig. 32) is a Sporozoon easily obtained for study 

 in the laboratory, since it is a parasite in the seminal vesicles of 

 the common earthworm. It is about y^ inch long. No 

 locomotor organs of any kind are present. The life history of 

 Monocystis is shown in Figure 32, and may be described briefly 

 as follows. 



The animals are in some unknown way transferred from one 

 earthworm to another as spores (Fig. 32, K), each containing 



