492 



SYSTEMATIC HISTOKY OF THE INPUSOEIA. 



M. urceolaris. — Very small^ m'ceolate, 

 obliquely emarginate in front; colour- 

 less,^ transparent, with scarcely an ap- 

 preciable differentiation of substance ; 

 . filament indicated by the movement 

 produced in the water at the anterior 

 extremity; motion slow. 1-2640". 

 In brooks with Hysgmum pluvialis. 



M. excavata. — Round or oval, with a 

 conspicuous speck in the anterior half; 

 colourless, or occupied with amorphous 

 bro^aiish or gi'eenish matter ; filaments 

 very fine, from 2 to 2-^ times longer 

 than the body. Motion active, in a 

 straight line, and rarelv revolving. 

 1-2100" to 1-1200". At Berne, in ponds 

 among Chara. 



M. Rotulus. — Elongated, cylindrical, 

 of a homogeneous pale-green colom' ; I 



Fresenins has added the foUowing species of Monas to the number already 

 distinguished : — 



filament apparently short ; onward 

 movement slow, although it revolves 

 i-apidly upon its long axis. 1-3000" 

 to 1-600". 



M. Farcimen. — Cylindrical, greenish, 

 with red spots ; flexible ; onward move- 

 ment and rotation rapid. 1-1800" 

 to 1-1080". 



M. Hilh. — Globular, or slightly elon- 

 gate ; of a dusky -green or brown colour. 

 Larger specimens at times present a 

 clear areola around colom-ed contents, 

 with vacuoles in the latter ; progression 

 tolerably fast, turning more rapidly on 

 the long axis. Length from 1-6000" to 

 1-600". The three species last named 

 approach very closely to sporozoids of 

 plants. 



Monas truncata. — Hyaline, colom*- 

 less ; figm'e oval and rounded, trmicate 

 anteriorly, compressed; one larger and 

 many smaller vacuoles often seen, the 

 former near the middle. The truncate 

 end supports two filaments, mostly on 

 one side, equal to or rather longer than 

 the body. Close beneath the anterior 

 margin a small transverse coi-puscle is 

 mostly visible, of a faint green hue, and, 

 some way beneath this, a small contractile 

 vesicle. A side view shows a slight 

 hollow on the under surface. Swims 

 without revolving, and mostly in a 

 straight course. 1-150 to 1-100 millim. 

 in diam. 



M. consociata. — Ovate, with one end 

 tapering and trunk-like, and tenninated 

 by a filament more than double the 

 length of the body. The proximal half 

 of this filament often seems rigid, and 

 only the distal or terminal half, which 

 is difficult to detect without the use of 

 iodine, motile. Body and its corpuscles 

 colom-less ; among the latter is one pro- 

 minent vacuole, not contractile. A mul- 

 titude of these Monads occupied a trans- 

 parent mucoid matter, which was not 



seen in motion. In still spring-water at 

 Walldorf in Jime and July. It bears the 

 nearest i-esemblance to Cercomonas vorti- 

 cellaris (Perty). 1-100 to 1-75 millim. 



M. Oherhauserii. — A carmine-coloured 

 Monad found in the sulphureous spring 

 at Frankfort, allied to 3fonas Okenii 

 (Elir.), and possibly the same as Chro- 

 matmm Weissii (Perty). Cylindrical, 

 rounded at each end, hyaline ; faintly 

 carmine-coloiu-ed, with a variable nmu- 

 ber of intensely crimson globules inter- 

 nally. Some specimens, however, have 

 only a homogeneous red colom*. Trans- 

 verse fission frequently seen. It rotates 

 rapidly, and advances with a tumbling 

 sort of movement, no doubt by means of 

 a filament ; but this eludes observation. 

 1-83 to 1-46 miUimetre. 



M. hipunctata. — A much smaller 

 species was found in the same glass with 

 the preceding, having a red colom*, an 

 elongated oval figm^e, and a red point 

 at each end. Longer specimens were 

 noticed with fom' such red points, which 

 might be in the act of fission. This 

 fonn may be the same as the Monas 

 rosea of Mon-en. 



Genus UYELLA (XYIII. 3, 4). — WeU characterized by the aggregating 

 together occasionally of the individual Monads, so as to foiTu a grape- or 

 mulberry-like mass, and by their generally possessing two (?) hair-like fila- 

 ments at the mouth. Like the Monads, says Ehrenberg, they are deficient of 

 the projecting lips, visual organ, and tail, and have the mouth situated at the 

 anterior extremity. They progress also in the direction of the longer axis of 

 theu' body, and are capable of complete self- division. Of the several species, 

 three are green, and the remainder colourless. 



This genus belongs to the Aggregate Monadina of Dujardin, and is thus 



