OF THE TKACHELINA. 627 



This is a new genus instituted by Ehrenberg. Its essential distinction from 

 Nassida is not pointed out, the only one indicated being the prolongation of 

 the frontal region beyond the oral apertui-e. 



lAOSip-no^ Strompkii. — Obtuse, ovate ; | pharynx of a clavate outline. 1-36'". 

 of a variegated green coloiu' ; tube of | With Oscillatorics. 



The genera named by Dujardin, ha\-ing a near affinity ^ith Bursaria, are 

 Plagiofoma, Kondylostoma, Oj^yalina, and Fanophrys. Two others, Acineria 

 and Pelecida (Duj.), are described as allies of Trachelius. 



Genus OPALINA. — Already described in the Astomatous family Opalinaea 

 (vide p. 569). 



Genus PLAGIOTOMA (Duj.).— Body very flat or lamellar, very flexible, 

 irregularly oval ; sinuous or emarginate on one side, and sometimes angular 

 behind ; covered with cilia in regular rows ; mouth lateral, near the middle, 

 at the bottom of the depression, with a row of strong and very numerous cilia 

 in advance of it on its anterior margin, having a comb-like aspect. 



of a yellowish grey colour from contained 

 molecules. Owing to its want of trans- 

 parency, tlie fine short cilia are visible 

 only around the peripherv. Motion ex- 

 tremely languid, oscillating and revolv- 

 ing. 1-260". In the interior of Ano- 

 donta Cellensis. 



Plagiotoma Lumhrici = Paramecium 

 compressum (Ehr.). — Stein shows this to 

 be a true Bursaria (see p. 622). 



P. concha rum (Perty) = Leucophrys 

 Anondontce (Ehr.). — This and the fore- 

 going are, in Stein's opinion, Opalince 

 (see p. 670). 



P. (?) difformis. — Irregular, thick, and 



Genus K0:N"DYL0ST0MA (Duj.).— Body more or less elongated, cylin- 

 drical or fusiform, rather crescentic, with obtuse and flattened ends ; mouth 

 very large, bordered by very strong cilia, and placed on one side near the 

 anterior extremity ; surface obliquely striated and ciliated. It swallows its 

 food, consisting of other animalcules or of vegetable debris, rather after the 

 manner of Plana rice than of Paramecina ; for it does not draw it in by the 

 action of its cilia in producing a vortex. It lives only in smooth and pure 

 sea- water among Algse, itc. 



KoNDYLOSTOMA patcns. — Body white, 

 or colom-ed by the food received ; at times 

 vermiform, at others fusiform, and often 



modified in figure by the bulk of food 

 swallowed. 



Genus PAIN'OPHEYS (Duj.) (XXYI. 33).— Ciliated throughout; oval, 

 depressed, contractile ; becoming ovoid, or even globular, during contraction ; 

 smface marked by straight or oblique ciliated striae, crossing one another ; 

 mouth lateral. Dujardin writes — '' Being desirous of characterizing Bur- 

 saria by the row of large cilia, en moustache, which lead to the mouth, I have 

 thought it right to establish a new genus for certain Biirsarice of Ehrenberg, 

 which are devoid of this character, and whose mouth is surrounded by only 

 ordinary cilia." UnUke the Paramecia, they have no anterior oblique fold 

 or fossa, and are able to contract themselves into a ball. They differ from 

 Holophrya by their lateral mouth. They live either in fresh smooth water, 

 or in sea-water among plants. 



In Perty's system it constitutes a member of the family Paramecina ; and 

 this is its tnie position, if the cilia are throughout of equal length. Indeed 

 the characters assumed to be distinctive of it from Paramecium appear to us 

 inconclusive. A lateral fold or vestibulum leading to the mouth is not entirely 

 wanting, although less developed than in most Paramecia ; and as to their 



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