Phylum Ciliophora [ 233 



ben. Spirochona and a few other genera, attached to aquatic animals, fresh-water or 

 marine, best known from the crustacean Gammarus. 



Order 4. Hypotricha Stein Org. Inf. 2 : 168 ( 1867) . 



Section Hypotricha Biitschli in Bronn Kl. u. Ord. Thierreichs 1: 1674 (1889). 

 Order Hypotrichaceae Hartog in Cambridge Nat. Hist. 1: 137 (1909). 

 Order Hypotrichida Calkins Biol. Prot. 389 (1926). 

 Suborder Hypotricha Kudo Man. Protozool. ed. 3: 668 (1946). 

 Suborder Hypotrichina Hall Protozoology 381 ( 1953 ) . 

 Flattened Infusoria bearing a band of membranelles crossing the upper surface 

 near the anterior end from right to left and continued rearward on the lower surface 

 beside the cytostome, along which lie also undulating membranes; mostly bearing 

 cirri, which are confined to the lower surface, as are most free cilia, if these are 

 present. 



This group is evidently natural, and evidently a specialized offshoot from the pre- 

 ceding order. It might reasonably be treated as a subordinate group of the preceding 

 order; Biitschli, Kudo, and Hall have done so. There are comparatively few species. 

 Several are familiar in infusions and have been much studied. 



Family 1. Peritromina Stein Org. Inf. 2: 168 (1867). Family Peritromidae Kent. 

 Cilia abundant on the lower surface, cirri none. Peritromus. 



Family 2. UrostyUda [Urostylidae] Calkins Biol. Prot. 390 (1926). As above, but 

 with frontal and sometimes also anal cirri. Numerous genera, Urostyla, Uroleptus, 

 Epiclintes, Stilotricha; Kerona O. F. Miiller, an ectoparasite on the animal Hydra. 

 Family 3. Oxytrichina Ehrenberg Infusionsthierchen 362 (1838). Family Oxytri- 

 chidae Kent. Family Pleurotrichidae Biitschli. Cirri present; cilia in one or two mar- 

 ginal rows, few or absent on the ventral surface. Oxtricha, Stylonychia, Pleurotricha, 

 Euplotes, etc. 



Order 5. Stomatoda Siebold in Siebold and Stannius Lehrb. vergl. Anat. 1: 10 

 (1848). 



Order Ciliata Perty Kennt. kl. Lebensf. 137 (1852). 



Order Peritricha Stein Org. Inf. 2: 168 (1867), 



Section Peritricha Biitschli in Bronn Kl. u. Ord. Thierreichs 1: 1674 (1889). 



Order Peritrichaceae Hartog in Cambridge Nat. Hist. 1: 138 (1909). 



Order Peritrichida Calkins Biol. Prot. 395 (1926). 

 Infusoria having a dextrorse spiral band of membranelles about the cytostome, 

 which can in most examples be concealed and protected by contraction of the body; 

 free-swimming only in the immature condition, at maturity attached and without 

 separate cilia; syngamy occurring by the complete union of a smaller swimming indi- 

 vidual with a larger attached one. Vorticella is the apparent type of the old ordinal 

 names Stomatoda and Ciliata, which are accordingly held to belong to this order. 



Family Vorticellina Ehrenberg Infusionsthierchen 259 (1838). Family Vaginifera 

 Perty (1852). Family Vorticellidae Fromentel 1874. Vorticella L., a familiar mic- 

 roscopic organism in material from ponds and ditches, consists of solitary bell-shaped 

 cells on contractile stalks. Carchesium and Zoothamnium are similar organisms in 

 colonies. Ophrydium, Epistylis, etc., consist of similar colonies of non-contractile 

 cells. Cothurnia and Vaginicola are solitary stalkless cells having conical loricae into 

 which they can withdraw themselves. 



