292 BIOLOGY OF THE PROTOZOA 



Family 7. Cryptobiidse, Leith. —Highly metabolic parasitic forms 

 with ])rimary, free, flagelhim and with undulating membrane ending 

 in a terminal posterior whip. Two genera: Cryptobia {Trypano- 

 pJasnia), chiefly fish blood parasites, and Trypanophis, a parasite 

 of wSiphonophora. 



Family <S. Amphimonadidse, Doflein,— Forms with two equal 

 flagella, naked and free-swimming, or in some types living in gela- 

 tinous houses or tubes. Colony formation is frequent; contractile 

 vacuoles simple, one or two in number. Reproduction by simple 

 division in the free-swimming state. 



Family 9. Monadidse, Stein.— Free-living or attached forms 

 provided with two dissimilar flagella, one of which, secondary, is 

 quite short. Contractile vacuoles simple and one or two in number. 

 Colony formation frequent. Some species of Monas and of Antlio- 

 physa form cysts which are similar to those of Chrysomonadida in 

 having neck-like processes closed by plugs (Fig. 5, p. 24); silica, 

 however, has not been detected in the cyst walls. 



Family 10. Bodonidae, Biitschli.— Monads with two flagella one 

 of which (primary) is directed forward, the other (secondary) drags 

 behind. In many cases both arise from a w^ell-marked snout-like 

 process (Bodo) which, in Rhynchomonas, is drawn out into a ten- 

 tacle replacing the primary flagellum. In Dinomonas both flagella 

 are directed forward and are of almost equal length. The kinetic 

 apparatus is complex; contractile vacuoles simple, often numerous. 

 Nutrition is holozoic and reproduction is by simple division. Sexual 

 processes have been described but without satisfactory evidence. 



Order III. POLYMASTIGIDA, Blochmann. 



The flagellates included in this Order are again a heterogeneous 

 lot and their classification is purel\' tentative. Many of them are 

 extremely minute and details of structure, particularly of the deli- 

 cate flagella and their distribution on the body, are easily overlooked 

 or misinterpreted. Syn(^nym\' in consequence is A'ery confused. 

 After trying in vain to harmonize the many taxonomic systems 

 which have been advocated I have abandoned the idea of grouping 

 forms in sub-orders and families which connote genetic relationships, 

 and in the following classification have presented the established 

 genera according to their similarities in structure under the non- 

 committal terms of "Tribes" and "Groups." 



The structural elements on which the grouping is based are 

 flagella, cytostomes and kinetic elements, the axostyle in particular. 

 Tribes are designated according to the single (Monozoa) or double 

 (Diplozoa) condition of the cytostome and accompanying kinetic 

 elements; or multiple (Polyzoa) according to the presence of many 



