OF THE OXYTRICHINA. 



643 



Alastor in Perty's system, detached from 

 other Ciliata by reason of its parasitic 

 habits, and placed vnihPlagiotoma (Duj.) 

 and Opalina in a family named Cobalina. 



K. pustulata (J)\x\.) = StyIoHychia pus- 

 tidata. 



K. Histrio (T>\i].) = St. Histrio. 



K. Mytilm {Y)uy) = St. Mijtilus. 



K. Silurus (Diij.) = '^i^. Silurus. 



K. lanceolata = St. lanceolata. 



K. Calvitium (Miill.), K. Jimhriata 

 (Miill.), and Triehoda foveata and Tr. 

 Camelus (MiilL), are probably, according- 

 to Dujardin and Perty, mere' varieties of 

 K. pustulata. 



K. Pullaster (Mull.) is cited by Ehren- 

 berg as = Oxytricha Pullaster, but, as 

 Dujardin thinks, is only an imperfectly- 

 examined or a deformed specimen of 

 St. pustulata. 



Genus UROSTYLA (XXV. 342).— CiHa and styles present, uncini want- 

 ing ; the cilia are thickly disposed in numerous rows, and are longer near 

 the mouth. On the ventral surface, at the posterior end, is a small cleft, 

 provided with non-vibratile setae. Internally are numerous vacuoles, which 

 may be filled with particles of colour ; a nucleus, a contractile vesicle, and 

 Transverse self-division has been observed. 



delicate granules. 



Urostyla gmndis (xxv. 342). — 

 White, semicylindrical, rounded at the 

 ends ; slightly enlarged anteriorly, hence 

 club-shaped ; styles short ; mouth large, 

 one-fom-th to one-third the length of the 

 body. It has long cilia on both sides ; the 

 discharging orifice has from five to eight 

 little styles on the left side only ; sto- 

 mach-juice colourless. The young ani- 

 malcules are fiatter than the old ones. 

 (xxv. 342, an imder view with glands, 

 vesicle, and the cells filled with Bacil- 

 laria and colom-ed matter. Currents 



produced by the vibration of the cilia 

 about the mouth are also indicated in 

 the drawing.) On slimy dead sedge- 

 leaves. 1-144" to 1-96". Perty doubts 

 the independent specific character of this 

 form, and would rather consider it a 

 variety of Oxytricha fusca, or more pro- 

 bably of Oo platystoma in a further deve- 

 loped state ; for Ehrenberg admits that 

 the imcini at the posterior extremity are 

 small ; and if so, they can scarcely be 

 characteristic. 



Genus STYLONYCHIA (XXV. 343, 344 ; XXVIII. 10, 74-76 ; XXIX. 

 18). — Ciliated, and armed with styles and uncini variously disposed. 



In one species Ehrenberg thought he had traced the course of the alimen- 

 tary canal with its numerous digestive cells ; in the others, he found, coloured 

 food was received. Transverse and longitudinal self-di\ision occurs in two 

 species; transverse only in a third. In S. pustulata, the formation of 

 gemmae is said to occur. Perty remarks that Ehrenberg, without any suffi- 

 cient reason, has transferred many of the Keronce of Miiller to fStylonychia. 

 The granules and molecules are numerous, and often in heaps ; one or two 

 nuclei and a contractile vesicle are generally visible. 



STYi.ois!Ycm.x 3Iytilus (Triehoda 3Iy- 

 tilus, Kerona Mytilus, M. and Perty) 

 (xxviii. 10). — White, flat, oblong, 

 slightly constricted in the middle, ob- 

 liquely dilated anteriorly in the form of 

 a mussel. The extremities are so trans- 

 parent that they give it the appearance 

 of being covered with a shield ; but they 

 are soft, flexible, and ciliated. Dujardin 

 observes that the integumentary appen- 

 dages are very long, consisting of a row 

 of strong cilia in front, a series of uncini 

 and numerous styles behind. The line 

 of cilia leading to the mouth does not 

 reach the centre of the body. Its extre- 

 naities are so thin and flexible that they 

 yield before obstacles in their move- 

 ments, like the Ploesconia Patella. It 



differs little from S. (K.) pusttdafa, ex- 

 cept in size and the strength of its super- 

 ficial processes. The middle of the body 

 is sometimes filled with delicate white 

 granules. Often, however, as Perty men- 

 tions, the animalcule is coloured green 

 with chlorophyll received in its food. 

 This animalcule generally has a peculiar, 

 thrusting, forward-and-back movement, 

 but can climb, run, and swim nimbly, 

 usually with the back undennost. Ehr- 

 enberg foimd that a single animalcule 

 lived nine days : during the first twenty- 

 fom- hours it was developed by transverse 

 self-division into three animals; these 

 in twenty-four hom's more formed two 

 each, in the same manner; so that, by 

 self-division only (without ova), these 

 2t2 



