SUB-ORDERS: EUMONADEA AND CRASPEDOMONADEA 287 



of an undulating membrane. There is no cytostome. The flagellates 

 frequently assume a rounded leishmania form devoid of flagella. 



3. Family: bodonid^. Doflein, 1901. — Flagellates which have two 

 flagella, which arise near a laterally placed cytostome. One of the flagella is 

 directed backwards as a trailing flagellum. A parabasal body is associated 

 with the two blepharoplasts, which are separated from the nuclear mem- 

 brane. The encysted forms are ovoid structures containing a single flagellate. 



4. Family: PROWAZEKELLID^ Doflein, 1916. — Parasitic flagellates 

 which have two flagella, one directed forwards and the other backwards 

 as a trailing flagellum. The blepharoplasts are on the nuclear membrane. 

 The cysts are spherical structures, which increase in size after they are first 

 formed and produce within them a large number of daughter flagellates. 



5. Family: embadomonadid^e Alexeieff, 1917. — Flagellates with two 

 flagella, one directed forwards and the other backwards or laterally 

 through a large cytostome. The blepharoplasts, which lie near the nuclear 

 membrane, are not associated with a parabasal. The cysts are ovoid or 

 pear-shaped structures containing a single flagellate. 



6. Family: CHILOMASTIGID^. — Flagellates with four or more flagella, 

 one of which lies in a large cytostomal groove, while the others are directed 

 forwards. The blepharoplasts of the flagella are closely grouped together 

 near the nucleus, and there is no parabasal. The margins of the cytostomal 

 groove are supported by fibres. The cysts are ovoid or pear-shaped 

 structures containing a single flagellate. 



7. Family: CERCOMONADID^ Kent, 1880. — Flagellates which have one 

 or more flagella, the axoneme of one of which passes backwards over 

 the surface of the body, to which it is adherent, without development 

 of an undulating membrane. The blepharoplasts are upon the nuclear 

 membrane. The cysts are simple ovoid or spherical structures containing 

 a single flagellate. 



8. Family: CRYPTOBIID.E Poche, 1913. — Flagellates which have two 

 flagella, one of which is directed forwards while the other passes backwards 

 and is attached to the surface of the body, which may be raised into an 

 undulating membrane. The two blepharoplasts are separate from the 

 nucleus, and there is a parabasal associated with them. Cysts may or 

 may not be produced. 



9. Family: TRiCHOMONADiD^. — Flagellates which have three or more 

 flagella; one axoneme may pass backwards along the margin of an undu- 

 lating membrane. The blepharoplasts form a group near the nucleus, and 

 there may or may not be a parabasal. A pointed rod-like structure, the 

 axostyle, passes through the cytoplasm from the anterior to the posterior 

 end of the body, through which it protrudes. The cysts are ovoid or 

 spherical, and contain a single flagellate. 



