CLASSIFICATION OF THE INFUSORIA 53 



Subfamily 3. ErvilUiuE. The cilia are confined to the ventral surface or to a por- 

 tion of it. The posterior end invariably possesses a movable style arising from 

 the posterior ventral surface. 



Typical genera: .Ecjijria, Clap and Lach., 18.5S; Onychodactylus, Entz., 18S4; 

 Trochilia, Duj., 1841; Dysteria, Huxley, 1857. 



Suborder 2. Trichostomixa. In addition to the general coating of cilia there is 

 an undulating membrane or membranes at the edge of the mouth or in the 

 pharynx. The mouth is always open. 



Family 1 . Chiliferidw. The mouth is in the anterior half of the body or close to 

 the middle. The pharynx when present is short. The so-called "peristome 

 area" leading to the mouth is absent or only slightly developed. 



r«//)Mai ^e?iera; Leueophrvs, Ehr., 18.30; Glaucoma, Ehr., 1830; Dallasia, 

 Stokes, 1886; Frontonia, Ehr., 1838; Ophryoglena, Ehr., 1831; Colpidium, 

 Stein, 1860; Chasmatostoma, Engelmann, 1862; Uronema, Duj., 1841; 

 Urozona, Schewiakoff (Biitschli), 1888; Loxocephalus, Kent, 1881; Colpoda, 

 Midler, 1773. 



Family 2. Urocentridw. The mouth, with a long, tuliular pharynx, is in the centre 

 of the ventral side. The cilia are confinetl to two broad zones around the 

 body at each end. 



Typical genera: Urocentrum, Nitsch, 1827. 



Family 3. Mierothoracidw. Small asymmetrical forms, with the mouth invariably 

 in the liinder portion. The cilia are always more or less dispersed, sometimes 

 limited to the oral region. There may be one or two undulating membranes. 



Typical genera: C'metochilum. Perty, 1849; Microtliorax, Engelmann, 1862; 

 Ptychostomum, Stein, 1860; Ancistrum, !Maupas, 1883; Drepanomonas, 

 Fresenius, 1858. 



Family 4. Paramecidce. The mouth is sometimes in the anterior, sometimes in 

 the posterior, half of the body, and is accompanied by a large, triangular 

 "peristome area," running from the left anterior edge of the body to the 

 mouth. 



Typical genera: Paramecium, Stein, 1800. 



Family 5. Pleuronemidce. The mouth is at the end of a long peristome, which 

 runs along the ventral side; the body is dorsoventrally or laterally com- 

 pressed. The entire left edge of the peristome is provided with an undulating 

 membrane which occasionally runs around the posterior end of the peristome 

 to form a pocket leading to the mouth. The right edge of the peristome is 

 provided with a less developed membrane. There may or may not be a well- 

 developed pharynx. 



Typical genera: Lembadion, Perty, 1849; Pleuronenia, Duj., 1841; Cyclidium, 

 Ehr., 1838, a subgenus of the preceding; Calyptotricha, Phillips, 1882; 

 Lembus, Cohn, 1866. 



Family 6. Isotrichidce. The body is more or less plastic, but not contractile. The 

 cuticle is thick and provided with evenly distributed cilia. The mouth is 

 posterior and accompanied by a distinct pharynx. They are parasites in the 

 digestive tract of ruminants. 



Typical genera: Isotricha, Stein, 1859; Dasytricha, Schul)erg, 1888. 



Family 7. Opalinida\ The form is oval, and the body maj' be short or drawn out 

 to resemble a worm. They are characterized mainly by the absence of mouth 

 and pharynx. 



Typical genera: Anoplophrva, Stein, 1860; Hoplitophrya, Stein, 1860; Disco- 

 phrya. Stein, 1860; Opalinopsis, Fcettinger, 1881; Opalina, Purkinje and 

 Valentin, 1835; ^lonodontophrya, ^'ejdowsky, 1892. 



Order 2. Heterotrichida. Ciliata characterized by the possession of a uniform 

 covering of cilia and an adored zone, consisting of short cilia fused together into 

 membranelles. 



