CLASSIFICATION OF THE INFUSORIA 55 



face is similar to tliat of the preceding family. Almost invariably in these primi- 

 tive forms some of the anterior and some of the posterior cilia are fused into 

 large and more powerful appendages, the cirri, which are distinguished as the 

 frontal and anal cirri, respectively. In the majority of forms all of the cilia 

 are thus differentiated; strong marginal cirri are formed in perfect rows, and 

 ventral cirri in imperfect rows. In addition to the adoral zone of membra- 

 nelles, there is an undulating membrane on the right side of the peristome, 

 and, in some cases, a row of cilia between the membrane and the adoral zone. 

 These are the paroral cilia, and they form the paroral zone. 



Typical genera: Trichogaster, Sterki, 1878; Urostyla, Ehr., 1830; Kerona, Ehr., 

 1838; Epiclintes, Stein, 1862; Stichotricha,' Perty, 1849; Strongylidium, 

 Sterki, 1878; Amphisia, Sterki, 1878; Uroleptus, Stein, 18.59; Sparotricha, 

 Entz, 1879; Onychodromus, Stein, 18.59; Pleurotricha, Stein, 18-59; Gas- 

 trostyla, Engelmann, 1862; Gonostomum, Sterki, 1S78; Urosoma, Kowalew- 

 sky, 1882; O.xytricha, Ehr., 18.30; Stvlonvchia, Stein, 18.59; Actinotricha, 

 Cohn, 1866; Balladina, Kowalewsky, 1882; Psilotricha, Stein, 18.59; Tetra- 

 styla, Schewiakoff, 1892; Holosticha, Wrzesniowski, 1877. 



Family 3. Euplotidw. Hypotrichous ciliates, which are characterized mainly by 

 the considerable reduction of the cilia, frontal, marginal, and ventral cirri; 

 the anal cirri, on the other hand, are ahvays present. The macronucleus is 

 band-formed. 



Typical genera: Euplotes, Stein, 1859; Certesia, Fabre-Domergue, 1885; Dio- 

 phrys, Duj., 1841; Uronychia, Stein, 1857; Aspidisca, Ehr., 18.30. 



Order 4. Peritrichida. Ciliata usually of cylindrical or cup-like form, in which the 

 cilia are reduced, as a rule, to those which form the adoral zone, but sec- 

 ondary rings of cilia may be present. 



Family 1. Spirochonida:. Peritrichous ciliates in which the peristome is drawn 

 out into a curious funnel-like process, either simple or rolled. They are 

 parasitic forms in which reproduction by budding is characteristic. 



Typical genera: Spirochona, Stein, ISol; Kentrochona, Rompel, 1894; Kentro- 

 chonopsis, Doflein, 1897. 



Family 2. Lichnophoridee . In addition to the adoral zone, there is a secondary 

 circlet of cilia around the opposite end. The adoral zone is a left-wound 

 spiral. A single genus Lichnophora, Claparede, 1867, which is parasitic on 

 various marine arthropods. 



Family 3. Yorticellido'. Attached or unattached forms of peritrichous ciliates, in 

 which the adoral zone, seen from above, forms a right-wound spiral (dexio- 

 tropic). A secondary circlet of cilia around the under end may be present 

 either permanently' or periodically. 



Subfamily 1. Urceolarinoe. ^'orticellid£e having a permanent secondary circlet of 

 cilia which incloses an adhesive disk, and without a peristome fold. 



Typical genera: Trichodina, Stein, 1854; Cyclochfeta, .Jackson, 1875; Tricho- 

 dinopsis. Clap, and Lach., 1858. 



Subfamily 2. YorticeUidinw. Peritrichous forms without a permanent secondary 

 circlet of cilia, and provided with a peristome fold which can be contracted 

 sphincter-like to inclose the peristome. 



Typical genera: Scyphidia, Lachmann, 1856; Gerda, Clap, and Lach., 1858; 

 Astylozoon, Engelmann, 1862; Vorticella, Ehr., 18.38; Carchesium, Ehr. 

 18.30; Zoothamnium, Stein, 18.54; Glossatella, Butschli, 1888; Epi-stylis, 

 Ehr.,18.30; Rhabdostyla, Kent, 1882; Opercularia, Stein, 18.54; Ophrvdium, 

 Ehr., 18.38; Cothurnia, Clap, and Lach., 18.58; Vaginicola, Clap, and Lach., 

 1858; Lagenophrys, Stein, 1851. 



Subclass 2. Suctoria. Infusoria having no cilia during the adult .stages, but 

 provided with them during the embryonic period. In a few cases the cilia are 

 retained. They have tentacles of various kinds, some adoi^tetl for sucking, 

 some for piercing. 



