OF THE MONADINA. 



499 



Amphimonas disjKir (xyiii. 13 a, b). — 

 Oblong, of very variable form^ one or other 

 end constricted, or prolonged laterally 

 into two filaments. 1-3500" to 1-2900". 

 Movement active, jerking. 



A. Cauda ta. — Of very variable fonn, 

 mostly depressed, tubercular, convex on | 

 one side, angular on the other, ^vith a 

 filament proceeding from the summit of 

 each angle, 1-2180" to 1-1300". 



" This species seems to me," says Du- 

 jardin, "to be allied to the JBodo saltans 

 of Ehrenberg. In every example, I saw 

 two flagelliform filaments, one from the 

 anterior, the other from the lateral angle ; 

 a caudifomi prolongation, obtuse or drawn 

 out as^a third filament, often adhered to 

 the slide." 



^ A. brachiata. — Under this name is in- 

 dicated an animalcule of the family Mo- 

 nadina, which Dujardin only once met 

 with, of an ovoid or pp-iform shape, 

 filled mth granules, and giving oft' from 

 its narrower anterior end a simple flexu- 

 ose filament, too-ether ^^dth a variable 

 dilated lobe emitting two other fila- 

 ments having an imdulatory motion. 

 The animal progressed by leaps, revolv- 

 ing at the same time. 



A. exilis (Perty). — Colom* soft grey; 

 fio-ure wedge-shaped, oftentimes emar- 

 ginate anteriorly; filaments two, twice 

 the length of the body, colourless ; mo- 

 tion oscillating. 1-2000". 



Genus TREPOMONAS (D.) (XYIII. 16 & 27).— Body compressed, thicker 

 and more rounded posteriorly ; its anterior extremity presents two thin lobes, 

 bent to one side and each terminated by a flagellifonn filament, which pro- 

 duce an active whirling and jerking movement. 



" The examples of this genus are very common in all collections of marsh- 

 water containing decomposing plants, but are most diificult to determine, 

 owing to the irregularity of their form and the rapidity of their movements, 

 I have rather glimpsed than certainly detected their flageUiform filaments, 

 and have in vain attempted accui^ately to delineate them," 



Trepomonas agilis (xviii. 16, 27). — Body gi'anular, unequal, 1-1300". 



Genus HEXAMITA (D.) (XXVI. 1).— Animals with an oblong body 

 rounded in front, constricted and bifid or notched behind. Two to four fila- 

 ments extend from the anterior border ; and the two posterior lobes are pro- 

 longed as two flexuose filaments. 



This genus, characterized by the number of its motor filaments, appears 

 sufiiciently distinct from the preceding. Its species occur in decomposing 

 marsh-water and in the intestine of Batrachians, but not in artificial infu- 

 sions. 



Hexaishta nodidosa (xx^tc. 1). — Ob- 

 long, ^vith three or four longitudinal 

 rows of nodules, the two lateral of which 

 are extended into tapering slender lobes, 

 each terminated by a filament; move- 

 ment vacillating. 1-1-300" to 1-1500". 



H. itiflata. — Oval oblong, rendered 

 almost quadrangular by the processes 



Genus HETEROMITA (D.) (XXVI, 5; XVIII, 26).— Body globular, 

 ovoid, or oblong, with two filaments extending from the same point in front 

 —■one slender, undulating, and producing an onward movement, the other 

 thicker, stretching posteriorly, and free, or contracting adhesion with the glass 

 sHde along which it moves, so as to cause a sudden movement backwards. 



'' The several sections of the Monadina, together with the Thecamonadina 

 and the Euglenae, contain Infusoria possessing two filaments, by one of which 

 they progress, by the other adhere for support to any solid body, and produce 

 a sudden movement backwards by its contraction. To prevent confounding 

 specimens of these several families, the same distinctions which mark the 



2k2 



which give origin to the filaments. 

 1-600" to 1-1300". 



H. intestinaUs. — Fusiform, prolonged 

 into a bifid tail. Very common in the 

 abdominal cavity of the Batrachia (frogs 

 and newts). It moves in a straight line, 

 oscillating from side to side. 



