THE INFUSORIA 



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Family 2. Oxytrichidas. The peristome is not always distinctly marked off from 

 the frontal area. In the most primitive forms the ciliation on the ventral surface 

 is similar to that of the preceding family. Almost invariably in these primitive 

 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 dif- 

 ferentiated ; strong marginal cirri are formed in perfect rows, and ventral cirri in 

 imperfect rows. In addition to the adoral zone of membranelles, 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 par- 

 oral cilia, and they form the par-oral zone. Genera : I richogaster Sterki ('78) ; 

 Urostyla Ehr. ('30) ; Kerona Ehr. ('38) ; Epiclintes Stein ('62) ; Stichotricha 

 Perty ('49) ; Strongylidium Sterki ('78) ; Amphisia Sterki ('78) ; Uroleptus 

 Stein ('59) ; Sparotricha Entz ('79) ; Onychodromns Stein ('59) ; Pleurotricha 

 Stein ('59); Gastrostyla Engelmann ('62) ; Gonostomum Sterki ('78) ; Urosoma 

 Kowalewsky ('82) ; Oxytrtcha Ehr. ('30) ; Stylonychia Stein ('59) ; Actinotricha 

 Cohn ('66) ; Balladina Kowalewsky ('82) ; Psilotricha Stein ("59) ; Tetrastyla 

 Schewiakoff ('92) ; Holosiiclia Wrzesniowski ('77)- 



Family 3. Euplotidas. Hypotrichous ciliates, which are characterized mainly by the 

 considerable reduction of the cilia, as well as the frontal, marginal, and ventral 

 cirri; the anal cirri, on the other hand, are always present. The macronucleus 

 is band-formed. Genera : Eitplotes Stein ('59) ; Certesia Fabre-Dumergue 

 ('85); Diophrys Duj. ('41) ; Uronychia Stein ('57); Aspidisca Ehr. ('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 I. Spirochonidas. 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. Genera : Spirochona 

 Stein ('51) ; Kentrochona Rompel ('94) ; Ketitrochonopsis Dofiein ('97). 



Family 2. Lichnophoridae. 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 ('67), which is parasitic on various 

 marine arthropods. 



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

 which the adoral zone, seen from above, forms aright-wound spiral (dexiotropic). 

 A secondary circlet of cilia around the under end may be present either perma- 

 nently or periodically. 



Subfamily 1. Urceolarina . Vorticellida? having a permanent secondary circlet of cilia 

 which incloses an adhesive disk, and without a peristome fold. Genera : Trichodina 

 Stein ('54) ; Cyclochata Jackson ('75) ; Trichodinopsis Clap. & Lach. ('58). 



Subfamily 2. Vorticellidince. 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. Genera: Scyphidia Lachmann ('56); 

 Gerda Clap. & Lach. ('58); Astylozoon Engelmann ('62); Vorticella Ehr. 

 ('38) ; Carchesium Ehr. ('30) ; Zoothamnium Stein ('54) ; Glossatella Biitschli 

 ('88) ; Fpistylis Ehr. ('30) ; Rhabdostyla Kent ('82) ; Opercnlaria Stein ('54) ; 

 Ophrydium Ehr. C38) ; Cothuriua Clap. & Lach. ('58); Vaginicola Clap. & 

 Lach. C58) ; Lagenophrys Stein ('51). 



Subclass II. 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 adapted for sucking, some 

 for piercing. 



