THE MASTIGOPHORA 137 



Subclass I. FLAGELLIDIA. These are small organisms possessing usually a 

 sharply defined, mononucleate body with a definite anterior end in which are 

 inserted one or more flagella. They are actively motile during the greater 

 period of life, but all have the power of encystment. Reproduction occurs by 

 longitudinal division, usually during the flagellated stage, although it may take 

 place during resting phases. Nutrition is holophytic, holozoic, parasitic, or 

 saprophytic. 



Order i. MONADIDA. Small forms of Flagellidia having a simple structure. The 

 body is frequently amoeboid, with one or two flagella at the anterior end. There 

 is no distinct mouth-opening, but a localized area about the base of the flagella 

 serves for the ingestion of food particles. 



Family i. Rhizomastigidae. Simple, mouthless forms with one or two flagella and 

 an amoeboid body capable of putting out lobose pseudopodia like a rhizopod, or 

 stiff radial pseudopodia like a heliozoon. The contractile vacuole is frequently 

 at the posterior end. Food particles may be ingested at any part of the body 

 by the aid of the pseudopodia. Genera: Mastigamceba F. E. Schultze ('75) ; 

 Ciliophrys Cienk. ('76); Dimorpha Gruber ('81); Actinomonas Kent ('80); 

 Trypanosoma Gruby ('43) ; Mastigophrys Frenzel ('91 ). 



Family 2. Cercomonadidae. Oval or elongated forms which are frequently amoeboid 

 or changeable, but unable to form pseudopodia. There is one large flagellum 

 with a mouth area at its base. The family includes small forms, saprophytic, or 

 holozoic, or sometimes parasitic in nutrition. Genera : Cercomonas Dujardin 

 ('41); Herpetomonas Kent ('80), parasitic. Oikomonas Kent ('80); Ancyro- 

 monas Kent ('80) ; Phyllomonas Klebs ('93). 



Family 3. Codonoecidae. Small colorless monads which secrete and remain in a 

 gelatinous or membranous cup. Genera: Codonaeca James-Clark ('66) ; Platy- 

 theca Stein ('78 ). 



Family 4. Bikcecidae. Small monads of peculiar form. They are provided with a 

 cup, to which they are attached by a slender thread. The basal portion is 

 broader than the upper part, which bears a curious tentacle-like process. Nutri- 

 tion is holozoic ; the individuals are single or colony-forming. Genera : Bicosceca 

 James-Clark ('67) ; Poteriodendron Stein ('78). 



Family 5. Heteromonadidae . Small colorless monads which have, in addition to 

 the chief flagellum, one or two accessory flagella. They frequently form colonies 

 upon a common stalk. Increase of the individuals is by longitudinal division. 

 Genera: Monas Stein ('78); Dendromonas Stein ('78); Cephalothamnium 

 Stein ('78) ; Anthophysa Bory d. St. Vincent ('24) ; Epipyxis Ehr. ('38) ; 

 Amphimonas Kent ( : 8i) ; Spongomonas Stein ('78) ; Cladomonas Stein ('78) ; 

 Rhipidodendron Stein ('78) ; Diplomita Kent f8o). 



Order 2. CHOANOFLAGELLIDA. Flagellidia with one or- more collar-like pro- 

 cesses about the base of the single flagellum. 



Family i. Phalansteridae. Colony-forming Choanoflagellida. Each individual is 

 situated in a granular gelatinous tube. The gelatinous tubes form either a dis- 

 coid colony in which the single tubes are arranged radially, or a dichotomously 

 branched aggregate. Genera: Phalansterium Cienk. ('7)- 



Family 2. Craspedomonadidae . Solitary or colonial forms. The individuals are 

 naked, or lie in an incomplete cup, or in a gelatinous mass. Genera : Mono- 

 siga Kent ( 1 8o) ; Codosiga, James-Clark ('67) ; Codonocladium Stein ('78) ; 

 Hirmidhim Perty ('52) ; Proterospongia Kent ('81) ; Sphceroeca Lauterb. ('99) ; 

 Salpingceca James-Clark ('67) ; Polyceca Kent ('81) ; Diplosiga Frenzel ('91). 



Order 3. HETEROMASTIGIDA. A small group with various kinds of flagellated 

 organisms, which are sometimes naked and amoeboid, sometimes provided with 

 a complex membrane. The essential character is the possession of two or more 



