378 MICROBIOLOGY 



Class II. Heliozoa. The genera are confined mainly , to fresh 

 water and are never parasitic. They are subdivided into 

 four orders according to the nature of the skeleton. 



Class III. Radiolaria. Salt-water forms of protozoa, never 

 parasitic. 



Sub-phylum II. Mastigophora. Protozoa with flagella. 



Class I. Flagellata. Small forms with from one to several 



flagella; with a strong tendency to form colonies. 



Order 1. Monadida. Minute forms with from one to three 

 flagella. There is no definite mouth-opening and nutri- 

 tion is holozoic, saprophytic, or parasitic. The parasites 

 and commensals which belong to this order are species 

 belonging to the genera Cercomonas, Herpetomonas, 

 Piroplasma, Leishmania, and Trypanosoma (appendix 

 Spirocheta). 



Order 2. Choanoflagellida. With collar-like processes sur- 

 rounding the base of the flagellum; not parasitic. 



Order 3. Heterommastigida. With two or more flagella of 

 dissimilar length; the genus Bodo is parasitic. 



Order 4. Polymastigida. The flagella are numerous and of 

 similar or dissimilar size. Here are several ecto- and 

 endo-parasitic forms belonging to the genera: Costia, 

 Tetramitus, Trichomonas, Monocercomonas, Hexamitus, 

 Lamblia, Polymastix, Lophomonas, Trichonympha, 

 Pyrsonympha and Joenia. 



Order 5. Euglenida. Occasional parasites as Copromonas 

 in frogs. 



Order 6. Phytoflagellida. Flagellates with coloring matter 

 in the form of green, yellow or brown chromatophores. 

 Frequently colonial. Here belong the most frequent 

 sources of odors in drinking waters, the following 

 genera being especially noteworthy: Dinobyron, Synura, 

 and Uroglena, all colonial forms, with yellow chromato- 

 phores. 



Order 7. Silicoflagellida. A single genus of salt water mas- 

 tigophora with latticed skeleton. Distephanus, para- 

 sitic on radiolaria. 



Class II. Dinoflagellata. Never parasitic. 



Class III. Cystoflagellata. Two genera of characteristic form. 



One, Noctiluca, is remarkable for the vivid phosphorescence 



which it causes. 



