30 



PROTOZOA. 



1896), seems to be a form exactly intermediate between the two groups. On the 

 other hand the Flagcllata show distinct affinities to the lower plants by such 

 forms as the Volvocina, which Klebs replaces amongst the Algce, and by the 

 Chrysomonadina and Cryptomonadina, which he unites into a special group the 

 Chro)iiomonadina of the Flagellata. 



Sub-order 1. MONADINA. 



Small to very small forms of simple structure, naked and often more or less 

 amoeboid, sometimes with tests ; usually colourless, rarely with chromatophores ; 

 with one anterior large flagellum, to which may be added one or two small 

 flagella ; special mouth-opening sometimes absent, sometimes present, but never 

 continued into a well-developed pharynx. 



Fam. 1. Rhizomastigina. Simple, monthless forms with one or two flagella, 

 and in some cases the power of thrusting out pseudopodia ; in other cases the 

 amceboid condition may be assumed with or without retraction of the flagella. 

 Mastigamceba F. E. Sch., fresh-water ; Ciliophrys Cienk., fresh-water, heliozoon- 

 like ; Dimorpha Gruber ; Actinomonas Kent ; Trypanosoma Gruby, parasitic 

 forms from blood of Amphibia, Pisces and Chelonia, with undulating membrane. 



FIG. 2fj. Englena viridis. a and &, free-swimming in different stages of contraction ; 

 c, d, e, encysted and in process of division. 



Fam. 2. Cercomonadina. Form oval to elongated, often amoeboid ; one 

 large, forwardly-directed flagellum with mouth, as a vacuole for taking up 

 food, at its base. Cercomonas Dujardin (Fig. 21), fresh-water and infusions, 

 hind end continued into pseudopod-like fibre ; Herpetomonas Kent, parasitic, 

 gut of MUSCM ; and Trilobus, blood of Mus ; Oikomonas Kent (Fig. 23), fresh- 

 water, infusions and marine ; Ancyromonas Kent. 



Fam. 3. CodoncECina. Monad with attached gelatinous or membranous cup. 

 Ccdonceca James Clark, salt and fresh -water ; Platytht.ca Stein. 



Fam. 4. Bikcecina. Monads with cup ; hind end fastened to base of cup 

 with contractile stalk ; cup usually fastened by stalk ; some colonial. Bicosceca 

 Clark, fresh-water and marine ; Paste riodcndr on Stein, fresh-water. 



Fam. 5. Heteromonadina. Small, colourless monads with an anterior large 

 flagellum, one or two contiguous smaller accessory flagella ; often colonial and 

 then stalked. Monas Ehrb. ; Dendromonas Stein, fresh-water ; Ceplialothamnium 

 Stein, attached to Cyclops ; Anthophysa Bory d. Vine., fresh-water ; Dinobryon 

 Ehrb. ; Uroghna Ehrb. 



Sub-order 2. ETJGLENOIDEA. 



Monoflagellate forms ; body contractile or stiff ; mouth and well-developed 

 pharynx at base of flagellum ; contractile vacuole near pharynx, often witJi 

 reservoir. 



