48 GENERAL ORGANIZATION OF THE PROTOZOA 



Tribe 4. Trichomjinphinea. Parasitic forms of the digestive tract covered with a 

 coating of long fiagella. 



Typical genera: Trichonympha, Leidy, 1877; Pyrsonympha, Leidy, 1877; Jenia, 

 Grassi, 1885. 



Order 6. Euglenida. Large forms of flagellates possessing one or two flagella, a 

 contractile often complicated body wall, a mouth and pharyngeal opening 

 at the base of the flagellum through which the contractile vacuole opens to 

 the ou.tside; chromatophores are often present and colony forms are not 

 uncommon. 



Family Euglenida;: The organisms are elongate with more or less pointed ends and 

 usually with one flagellum. The membrane is marked with spiral stripings 

 indicating the course of the myonemes. Red eye spots, and green chromato- 

 phores are usually present. Pyrenoids and paramylum granules usually 

 present in abundance. 



Typical genera: Euglena, Ehr., 1830; Trachelomonas, Ehr., 1833; Phacus, 

 Nitsch, 1816. 



Family Astaaiidae: The body is elongate and usually provided with a striped 

 membrane and otherwise similar to Euglena, but there are no eye spots and 

 the body is always colorless. 



Typical genera: Astasia, Ehr., 1838; Rhabdomonas, Fres., 1858. 



Family Peranemidce: The body is either stiff or plastic, and is usually symmetrical. 



Typical genera: Peranema, Dujardin, 1841 ; Petalomonas, Stein, 1859. 



Order 7. Silicoflagellida. Organisms with a peculiar lattice-like skeleton of 

 silica, one flagellum, and simple structure. Parasitic on radiolaria. 



Typical genus: Distephanus, Stohr, 1881. 



Subclass 2. Choanoflagellata. Simple flagellated protozoa with a well-defined and 

 characteristic protoplasmic collar surrounding the base of the flagellum. 

 They frequently form colonies in which the cells are embedded in a gelatinous 

 or a chitinous matrix. 



Typical genera: Monosiga, Kent, 1880; Codosiga, James-Clark, 1867; Pro- 

 terospongia, Kent, 1880; Diplosiga (with two collars), Frenzel, 1891 ; Phalan- 

 sterium, Cienk., 1870. 



Class II. PHYTOMASTIGOPHORA. Flagellated forms in which the plant char- 

 acteristics, if not predominant, are clearly marked. Here are classified the 

 majority of complex colony forming types, but the single cells are invariably 

 of simple structure, possessing eye spots, pyrenoids, and yellow, green, or 

 brown chromatophores. 



Subclass 1. Phytoflagellata. In this group the organisms have yellow or green 

 chromatophores. 



Order 1 . Chrysoflagellida. With yellow chromatophores. 



Typical genera: Chromulina, Cienk., 1870; Dinobryon, Ehr., 1838; Hyalobryon, 

 Lauterborn, 1899; Mallomonas, Perty, 1876; Synura, Ehr., 1833; Uroglena, 

 Ehr., 1833; Chrysospherella, Lauterb., 1899;" Cryptomonas, Ehr., 1831; 

 Chilomonas, Ehr., 1831 (without chromatophores). 



Order 2. Chloroflagellida. With green chromatophores. 



Typical genera: Chlorogonium, Ehr., 1835; Polytoma, Ehr., 1838; Hemato- 

 coccus, Agardh., 1828; Phacotus, Perty, 1852; Gonium, O. F. Miiller, 1773; 

 Pandorina, St. Vincent, 1824; Eudorina, Ehr., 1831; Pleodorina, Shaw, 

 1894; Platydorina. Kofoid, 1899. 



Subclass 2. Dinoflagellata. Organisms with yellow or brown pigment, two or more 

 flagella, and an outer shell of cellulose secreted in the form of plates. The 

 body is usually cut by furrows, of which the transverse is the more important; 

 one flagellum lies in this furrow, while the other is extended in advance of the 

 organism. The two flagella combine to give a rotation and forward movement 

 at the same time. 



