Phylum Protoplasta [ 163 



Family 4. Cliaetoproteida [Chaetoproteidae] Poche in Arch. Prot. 30: 172 (1913). 

 Family Rhizomastigina Biitschli in Bronn Kl. u. Ord. Thierreichs 1: 810 (1884). 

 Family Rhizomastigaceae Senn in Engler and Prantl Nat. Pflanzenfam. I Teil, Abt. 

 la: 113 (1900). Family Mastigamoebidae Kudo Protozoology ed. 3: 263 (1946). 

 Amoeboid organisms bearing one anterior flagellum, either permanently or tempor- 

 arily. In polluted soil or water, or commensal or pathogenic in animals. 



The oldest genus, Chaetoproteus Stein {Mastigamoeba F. E. Schulze, 1875; Din- 

 amoeba Leidy ?) remains poorly known. This organism and Mastigella are described 

 as fairly large; Craigia is much smaller. Rhizomastix is doubtfully distinct from 

 Craigia. Early names of this family appear to refer to Rhizomastix as the type, but 

 the family is much older than the genus, and the names are not valid. 



Order 2. Polymastigida Calkins Biol. Prot. 292 (1926). 



Family Polymastigina Biitschli in Bronn Kl. u. Ord. Thierreichs 1: 842 (1884). 

 Order Polymastigina Blochmann Mikr. Tierwelt ed. 2, 1: 47 (1895). 

 Subclass Distomatineae Engler in Engler and Prantl Nat. Pflanzenfam. I Teil, 



Abt. la: iv (1900). 

 Order Distomatinales Engler Syllab. ed. 3: 7 (1903), not based on a generic 



name. 

 Orders Pyrsonymphina, Oxymonadina, Retortomonadina, and Distomata Grasse 

 Traite Zool. 1: fasc. 1: 788, 801, 824, 963 (1952). 

 Non-pigmented flagellates with simple or acroneme flagella of definite number, 

 from four to eight (two in Retortomonas), in the individual neuromotor system, and 

 accordingly on the individual cell, except when the neuromotor systems are multi- 

 plied; not of the definite characters of the following order. Free-living, chiefly in 

 foul waters, or commensal or parasitic in animals. Polymastix is presumably the type 

 of the group. It was listed with a query in Biitschli's original publication of family 

 Polymastigina. 



In the generality of Polymastigida, the cells are dorsiventral and have single nuclei 

 and neuromotor systems. There are derived examples in which the cells are spirally 

 twisted. There is a group in which the cells are double, having two nuclei and neuro- 

 motor systems. In another group there are two or more neuromotor systems, usually 

 with more than one nucleus; the cells consist of units in a whorled or spiral arrange- 

 ment, so that as wholes they are of radial symmetry. 



The neuromotor system consists primarily of ( 1 ) the flagella; (2) one or more 

 blepharoplasts from which the flagella spring; (3) one or more rhizoplasts linking 

 together the parts of the system; and (4) a centrosome located just outside the nuclear 

 membrane. Furthermore, (5) a parabasal body may be present. (6) An axostyle is a 

 rod imbedded in the cytoplasm. In Hexamita the axostyles are the proximal ends of 

 backwardly directed flagella; axostyles occurring in various other genera of the order 

 appear also to be homologous with flagella. 



Nuclear and cell division have been observed in various genera, as in Hexamita by 

 Swezy (1915); in Streblomastix by Kidder (1929); in Giardia by Kofoid and Chris- 

 tianson (1915) and Kofoid and Swezy (1922); and in O.V);mona^ by Connell (1930). 

 Cleveland (1947) observed in Saccinobaculus a multiplication of nuclei followed 

 by their fusion in pairs, and by meiosis in the fusion nuclei: thus there is a .sexual 

 cycle without fusion of cells. It is not probable that sexual reproduction does not 

 occur in the generality of the group, but it has not been observed in any others. 



